Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Effect of PEG-induced drought stress on seed germination of four lentil genotypes

Effect of PEG-induced drought stress on seed germination of four lentil genotypes Journal of Plant Interactions, 2014 Vol. 9, No. 1, 354363, http://dx.doi.org/10.1080/17429145.2013.835880 RESEARCH ARTICLE a a b a c Adele Muscolo *, Maria Sidari , Umberto Anastasi , Carmelo Santonoceto and Albino Maggio Dipartimento di Agraria, Universita` ‘‘Mediterranea’’ di Reggio Calabria, Localita` Feo di Vito, 89126 Reggio Calabria, Italy; Dipartimento di Scienze delle Produzioni Agrarie e Alimentari, Universita` di Catania, Via Valdisavoia 5, 95123 Catania, Italy; Dipartimento di Ingegneria Agraria e Agronomia del Territorio, Universita` di Napoli ‘‘Federico II’’, Via Universita` 100, 80055 Portici, Napoli, Italy (Received 24 July 2013; accepted 13 August 2013) Seeds of four lentil genotypes (Castelluccio, Eston, Pantelleria, and Ustica) were subjected to five levels (0, 10, 15, 18, and 21%) of polyethylene glycol (PEG-6000). Germination percentage, root length, tissue water content (WC), a- and b-amylases, a-glucosidase activities, and osmolyte content were evaluated at 24, 48, and 72 h after starting the germination test. Water stress reduced seed germination percentage, root length, and seedling WC in all cultivars to different extent. The increase in proline content and total soluble sugars was greater for Eston and Castelluccio compared to the other genotypes. The activity of the enzymes involved in the germination process decreased in all cultivars; the activities of a-amylase and a-glucosidase were most negatively affected by osmotic stress, mainly in the drought sensitive Ustica and Pantelleria. Overall, Eston and Castelluccio were able to express greater drought tolerance and consequently could be used as a valuable resource for breeding programs. Keywords: amylase activity; drought; lentil; osmotic stress; proline; seed germination 1. Introduction (Arjenaki et al. 2011). The sequence of events leading to seed germination and root emergence is governed by Worldwide agricultural productivity is subject to water uptake from the external medium (Kaur et al. increasing environmental constraints in the form of 1998; Hodge et al. 2009). Water availability plays a abiotic stresses that adversely influence plants growth significant role in enzymatic reactions, solubilisation and development causing crop failure and decreasing and transportation of metabolites, and also as a average yields more than 50% (Buchanan et al. 2000; reagent in the hydrolytic breakdown of proteins, Bartels & Sunkar 2005; Mittler 2006; Wu et al. 2011). lipids, and carbohydrates in the storage tissues of In semiarid environments where lentil is widespread, germinating seeds (Bewley & Black 1994; Biaecka & unfavorable soil moisture at sowing often conditions Ke ˛pczyn´ ski 2010). Amylase enzymes play an impor- severely seed germination resulting in an irregular tant role during seed germination, hydrolyzing the seedling emergence, which in turn affects the estab- endosperm starch into metabolizable sugars, which lishment of a stand, with negative effects on the yield provide the energy for the growth of roots and shoots (Mwale et al. 2003; Okcu et al. 2005). For these (Nauriere et al. 1992). The activity of such enzymes is reasons, drought tolerance at the germination stage reduced by water stress with negative effects on has specific importance moreover in warm environ- carbohydrate metabolism (Kaur et al. 2000; Zeid & ments most vulnerable to climate change (IPCC Shedeed 2006). 2007). Selection of plants with a better drought tolerance Lentil (Lens culinaris L.), one of the oldest is critical in dry environments (Ashraf et al. 1992; domesticated plants in the world, originated from Tuberosa & Salvi 2006). However, controlled and the near East and central Asia, is traditionally uniformly repeated simulation of drought in the field cultivated in the Mediterranean basin (Zohary cannot be easily achieved (Shaheen & Hood-Nowotny 1972). Seeds of this species are an important source 2005). The slow progress in developing drought- of protein for the human diet and the entire biomass resistant cultivars also reflects the lack of a specific of plant is a valued animal feed. Irrigation generally method for screening the large numbers of genotypes increases lentil yield (Salehi et al. 2008), improving required in breeding for drought (Zeigler & Puckridge seed size, seed yield, biomass yield, and harvest index 1995). Using natural field conditions is difficult be- (Singh & Saxena 1990; Silim et al. 1993; Khourgami cause rainfall can eliminate water deficits. However, in et al. 2012). Thus, the successful crop establishment in semiarid areas depends on the rapid and uniform seed vitro drought-screening methods are facilitating pro- germination, which is strictly associated to the ability gress in our understanding of drought-resistance traits of seeds to germinate under low water availability and in our selection of drought-resistant genotypes. *Corresponding author. Email: [email protected] # 2013 Taylor & Francis Journal of Plant Interactions 355 Richards (1978) suggested germination as a useful to prevent evaporation and kept accordingly to a criterion in screening for water stress tolerance. Khak- completely randomized design in a growth chamber at wani et al. (2011) demonstrated that among the six a temperature of 25918C in the dark with a relative varieties of wheat tested, those who were tolerant to humidity of 70%. Seeds were considered germinated drought during in vitro germination tests were simi- when the radicle had extended for at least 2 mm. The water content (WC) was measured and expressed as a larly tolerant in field conditions. In addition, Agili et al. percentage according to the formula WC (%) (2012) confirmed this finding with experiments on (Fresh Weight  Dry Weight/Fresh Weight)100. sweet potato. Thus, study of the influence of the Root length (cm) was also measured and for each of drought using osmotic solutions is one of the methods four genotypes, five replicates were used. in the evaluation of resistance during the germination phase. Exposure to polyethylene glycol (PEG-6000) solutions has been effectively used to mimic drought 2.2. Enzyme activity stress with limited metabolic interferences as those The activities of a-amylase, b-amylase, and a-gluco- associated to the use of low molecular weight osmo- sidase were determined in the crude extracts of each lytes that can be taken up by the plant (Hohl & cultivar. The seeds of each cultivar and for each PEG Schopfer 1991). PEG-based in vitro screening for treatment (0, 10, 15, 18, and 21%) were homogenized drought tolerance has been proven to be a suitable in a chilled mortar with distilled water 1:4 (w/v) and method to effectively screen large sets of germplasm centrifuged at 14,000 g for 30 min. The supernatants with good accuracy (Kulkarni & Deshpande 2007). were filtered through a single layer of muslin cloth Understanding the biochemical mechanisms in- and were used for a-amylase (EC 3.2.1.1) (Steup volved in plant drought stress tolerance is still a major 1988), b-amylase (EC 3.2.1.2) (Steup 1988), and challenge in biology and agriculture to identify at a-glucosidase (EC 3.2.1.20) (Bergmeyer et al. 1983) early stage suitable traits that would support plant activity determination. breeders in specific selection programs. The main For a-amylase, a mixture of 3 ml soluble starch objective of this study was to evaluate the influence of (2% v/v) and 3 ml extract was incubated for 60 min at drought stress on seeds of the four cultivars of lentil, 308C. After incubation, an equal volume of alkaline which had previously shown to have diverse level of color reagent was added to 1-ml incubation mixture, tolerance to NaCl stress (Sidari et al. 2008), in order mixed and heated for five min in a boiling water bath. to select the best suitable parents for hybridization in The absorbance at 546 nm was measured against a breeding patterns. blank (1 ml H O plus 1 ml alkaline reagent). The standard curve was obtained by using different con- 2. Materials and methods centrations of maltose in the range of 01.5 mmol l . The alkaline color reagent was prepared by dissolving 2.1. Plant material, germination conditions, and 1 g of 3,5-dinitrosalycylic acid in a mixture of 40 ml experimental design 1 N NaOH solution and 30 ml H O. Solid potassium The following lentil cultivars were studied in this sodium tartrate was added and dissolved. The mixture experiment. Two salt stress tolerant landraces ‘Pan- was brought to a final volume of 100 ml (Steup 1988). telleria’ and ‘Ustica’: native and cultivated in the b-amylase was determined as described above but homonymous small islands close to Sicily (Southern soluble starch was replaced by amylopectin. For Italy), a local population ‘Castelluccio di Norcia’: a-glucosidase detection, the assay buffer consisted of cultivated in Umbria region (Central Italy), and a 50 mM Na-acetate, pH 5.2, containing 10 mM CaCl . Canadian commercial variety ‘Eston.’ Seven-month- The substrate was 10 mmol l maltose. The samples old seeds (stored at 20918C and 95% R.U.) of each were incubated for 60 min. The release of glucose was lentil genotype were used. The seeds were selected for followed by measuring the changes in NADPH at size homogeneity, surface-sterilized for 20 min in 30% 340 nm in a coupled enzyme reaction of hexokinase (v/v) H O , rinsed and soaked in distilled water for 1 2 2 and glucose-6-P dehydrogenase. For each treatment, h. For each of four genotypes, five replicates of 50- five replicates were used. seed were placed on a filter paper in 9-cm Petri dishes containing 3 cm of distilled water or 10, 15, 18, and 2.3. Osmolyte content 21% of PEG (MW 6000) concentration correspond- ing to final osmotic potentials of 0.30, 0.51, To detect free proline content samples (0.3 g) includ- 0.58, and 0.80 MPa, respectively. We used 10, ing 5 ml of 3% sulfosalicylic acid were homogenized 15, 18, and 21% of PEG to have an osmotic potential and centrifuged at 3000 rpm for 20 min. The super- comparable to that of NaCl at the concentrations of natant was added to 2 ml of glacial acetic acid with 50, 100, 150, and 200 mM that we tested on seed 2 ml acidic ninhydrin. The mixture was heated at germination of the same cultivars in a previous work 1008C for 25 min. After the liquid was cooled, the (Sidari et al. 2008), in order to evaluate similarity or mixture was added to 4 ml toluene. The absorbance of differences in the metabolic traits of salt and drought the extracts was read at 520 nm (Bates et al. 1973). The resistance. The Petri dishes were sealed with Parafilm total soluble sugars were determined with the 356 A. Muscolo et al. anthrone method (Yemn & Willis 1954). For each length decreased, increasing water stress and time but treatment, five replicates were used. with different extent (Table 2). By increasing PEG concentrations a different behavior among the culti- vars was observed. Eston and Castelluccio showed 2.4. Measurement times and statistical analysis a greater radicle elongation especially at 72 h in comparison to Pantelleria and Ustica. The greatest Root length, water content (WC), enzyme activity, radicle reduction was observed in Ustica and Pantel- and osmolyte content were measured at 24, 48, and leria at 48 and 72 h in presence of PEG at the 72 h after the start of the test. The data were concentrations of 18 and 21%. statistically analyzed separately for each time by a In all cultivars, in the absence of stress, the WC two-way ANOVA according to the adopted experi- increased over time (Table 3). The increase in both mental design combining PEG concentrations and duration and intensity of osmotic stress caused a genotypes. The germination percentage data were gradual decrease in the WC in each cultivar compared previously subjected to arcsine transformation and to controls. The presence of PEG at different con- were reported in tables as untransformed values. The centrations differently affected the cultivars over time. differences between the means were compared by the Increasing the duration of stress and the time, the WC least significant difference (LSD) test (p50.05). decreased in Pantelleria and Ustica and increased in Eston and Castelluccio. The lowest WCs were de- 3. Results tected at 72 h in Ustica and Pantelleria in presence of PEG at the highest (18% and 21%) concentrations. Germination was significantly affected by the osmotic Total soluble sugar content decreased during the potential, by cultivars and their interaction (Table 1). experimental time in Pantelleria and Ustica seeds. On Germination of all cultivars started 24 h after sowing. the contrary, as a consequence of the increasing The final germination percentage of the control (0% drought stress and time, in Eston and Castelluccio, a PEG) reached 100% for each cultivar but with gradual increase in total soluble sugars was observed different time. An increase in PEG stress markedly (Figure 1A) decreased the germination percentage of all cultivars Significant increase in free proline content was compared to their relative controls. Seventy-two also observed in seeds of all genotypes under water hours after sowing, the germination percentage of stress. Eston and Castelluccio under drought condi- Castelluccio and Eston at the highest PEG concen- trations (18% and 21%) was higher than that of tions, accumulated more proline than Pantelleria and Pantelleria and Ustica. Ustica (Figure 1B).The highest amount of proline was The effects of drought stress, cultivars, and their detected in the above two cultivars in presence of interaction were also significant on root length. Root PEG at the concentrations of 18 and 21% at 72 h. Table 1. Germination (%) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD (GC) 3.4 Mean (C) Eston 97 72 33 11 8 44b Castelluccio 98 47 15 4 3 33c Ustica 100 72 47 35 5 52a Pantelleria 100 71 44 35 1 51a Mean (G) 99a 66b 35c 21d 4e 48 LSD (GC) 3.5 Mean (C) Eston 99 80 71 67 44 72a Castelluccio 98 48 35 30 18 46c Ustica 100 76 53 49 27 61b Pantelleria 100 76 57 42 28 60b Mean (G) 99a 70b 54c 47d 29e 72 LSD (GC) 2.3 Mean (C) Eston 100 100 93 91 76 92a Castelluccio 100 71 64 61 47 69b Ustica 100 81 61 51 25 64c Pantelleria 100 81 64 52 28 65c Mean (G) 100a 84b 71c 64d 44e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) were compared according to LSD (p50.05). Journal of Plant Interactions 357 Table 2. Root length (cm) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD (GC) 0.31 Mean (C) Eston 0.69 0.36 0.23 0.17 0.12 0.32a Castelluccio 0.40 0.24 0.14 0.07 0.02 0.17d Ustica 0.52 0.27 0.20 0.15 0.08 0.25c Pantelleria 0.69 0.39 0.24 0.11 0.09 0.30b Mean (G) 0.57a 0.31b 0.20c 0.12d 0.08e 48 LSD (GC) 0.06 Mean (C) Eston 2.51 1.34 1.00 0.68 0.24 1.15a Castelluccio 1.10 0.83 0.76 0.52 0.20 0.68d Ustica 2.03 0.86 0.65 0.34 0.18 0.81c Pantelleria 2.85 0.92 0.77 0.47 0.18 1.04b Mean (G) 2.12a 0.99b 0.80c 0.50d 0.20e 72 LSD (GC) 0.06 Mean (C) Eston 4.31 2.22 1.74 1.02 0.83 2.02a Castelluccio 3.94 1.60 1.35 0.74 0.53 1.63b Ustica 4.15 1.49 1.12 0.42 0.22 1.48d Pantelleria 4.95 1.53 0.87 0.33 0.21 1.58c Mean (G) 4.33a 1.71b 1.27c 0.63d 0.44e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) were compared according to LSD (p50.05). The values of a-amylase, b-amylase, and compared to Ustica and Pantelleria with respect to a-glucosidase activities were constitutively different time and stress level. The activities of these enzymes in the seeds of the four cultivars (Tables 46).The showed a greater decreasing trend in Pantelleria and activity of these enzymes decreased in a dose depen- Ustica in presence of PEG at the concentrations of dent manner, differing among the cultivars. The 18% and 21%, already 24 h after sowing. Among activities of a-, b-amylase, and a-glucosidase in the enzymes involved in the germination process, stressed seeds of Eston and Castelluccio were higher, a-amylase and a-glucosidase were the most negatively Table 3. WC (%) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 2.3 Mean (C) Eston 19 16 17 14 14 16c Castelluccio 19 16 17 15 15 16c Ustica 25 24 21 19 15 21b Pantelleria 38 22 21 22 21 25a Mean (G) 25a 20b 19b 17c 16c 48 LSD p50.05 (GC) 2.5 Mean (C) Eston 39 27 28 27 21 29a Castelluccio 31 28 27 29 21 27b Ustica 33 34 24 20 16 25c Pantelleria 37 37 19 19 17 26c Mean (G) 35a 32b 25c 24c 19d 72 LSD p50.05 (GC) 2.9 Mean (C) Eston 40 34 30 26 24 31a Castelluccio 42 26 25 25 22 28b Ustica 35 31 14 12 10 20c Pantelleria 45 35 13 7 7 21c Mean (G) 40a 32b 20c 17d 16e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). 358 A. Muscolo et al. AB Pantelleria Pantelleria 0 h 0 h Ustica Ustica Eston Eston Castelluccio Castelluccio 0 0 24 h 24 h 0 0 48 h 48 h 0 0 72 h 72 h 0 0 0 5 10 15 20 0 5 10 15 20 PEG concentration % PEG concentration % Figure 1. Total soluble carbohydrates (A) and proline content (B) in Pantelleria, Ustica, Eston, and Castelluccio lentil genotypes seeds in 0, 10, 15, 18, and 21% PEG 6000 at 0, 24, 48, and 72 h. Vertical bars indicate SD (n5). affected by drought stress especially in Ustica and growth stage, stress duration, and severity. Germina- Pantelleria cultivars. tion is the most critical and sensitive stage in the life cycles of plants (Ahmad et al. 2009) and the seeds exposed to unfavorable environmental conditions 4. Discussion such as drought may compromise the subsequent Drought is a multifaceted stress condition that causes seedling establishment (Albuquerque & Carvalho serious crops yield limitations depending on plant 2003; Soleymani et al. 2012). Genetic variability –1 –1 –1 –1 Total soluble carbohydrates [mg g (dw)] Total soluble carbohydrates [mg g (dw)] Total soluble carbohydrates [mg g (dw)] Total solubre carbohydrates [mg g (dw)] –1 –1 –1 Proline [µg g (dw)] Proline [µg g (dw)] –1 Proline [µg g (dw)] Proline [µg g (dw)] Journal of Plant Interactions 359 1 1 Table 4. a-amylase activity (mmoles of reducing sugars formed min g f.w.) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 0.49 Mean (C) Eston 16.12 17.42 17.04 15.49 12.13 15.64c Castelluccio 17.18 16.77 12.41 11.90 11.12 13.88d Ustica 26.10 18.97 19.07 14.47 7.70 17.26b Pantelleria 36.42 31.35 25.28 17.01 7.39 23.49a Mean (G) 24.00a 21.12b 18.45c 14.71d 9.58e 48 LSD p50.05 (GC) 0.21 Mean (C) Eston 16.41 15.31 14.09 13.22 11.13 14.03c Castelluccio 15.52 14.06 13.37 12.06 11.88 13.37d Ustica 27.06 20.09 15.10 10.47 5.69 15.68b Pantelleria 36.05 21.07 13.91 11.22 6.64 17.78a Mean (G) 23.76a 17.63b 14.11c 11.74d 8.84e 72 LSD p50.05 (GC) 0.48 Mean (C) Eston 16.42 16.74 15.50 14.70 12.73 15.22c Castelluccio 12.11 11.97 11.52 11.46 11.06 11.62d Ustica 24.93 22.47 16.40 11.47 7.70 16.59b Pantelleria 36.14 25.20 21.12 18.60 6.73 21.56a Mean (G) 22.40a 19.09b 16.13c 14.06d 9.55e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). within a species offers a valuable tool for studying centrations of PEG reduce the final germination mechanism of drought tolerance. Our results high- percentages of lentil (Siahsar et al. 2010; Jamaati-e- lighted significant differences among the cultivars Somarin & Zabihi-e-Mahmoodabad 2011). In Med- exposed to drought stress with a remarkably de- iterranean semiarid regions, the topsoil WC during creased and delayed germination in Ustica and the dry season is drastically reduced, sometimes to Pantelleria. These results are consistent with those less than 1%, which is very close to the permanent of other studies that have reported that high con- wilting point estimated for xerophytes (Larcher 1995; 1 1 Table 5. b-amylase activity (mmoles of reducing sugars formed min g f.w.) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC). Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 0.09 Mean (C) Eston 0.75 0.65 0.54 0.43 0.38 0.55a Castelluccio 0.69 0.62 0.51 0.44 0.36 0.53a Ustica 1.03 0.55 0.45 0.22 0.19 0.49b Pantelleria 1.06 0.48 0.41 0.24 0.15 0.47b Mean (G) 0.88a 0.58b 0.48c 0.33d 0.27e 48 LSD p50.05 (GC) 0.33 Mean (C) Eston 0.91 0.88 0.84 0.80 0.64 0.81a Castelluccio 0.80 0.71 0.65 0.60 0.56 0.67b Ustica 1.40 0.75 0.45 0.34 0.23 0.63c Pantelleria 1.37 0.73 0.43 0.32 0.22 0.61c Mean (G) 1.12a 0.77b 0.60c 0.51d 0.41e 72 LSD p50.05 (GC) 0.13 Mean (C) Eston 1.17 1.09 0.80 0.73 0.75 0.91a Castelluccio 1.02 0.86 0.72 0.62 0.55 0.75c Ustica 1.55 1.35 0.60 0.45 0.24 0.83b Pantelleria 1.47 1.09 0.52 0.43 0.21 0.75c Mean (G) 1.30a 1.09b 0.66c 0.58d 0.44e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). 360 A. Muscolo et al. 1 1 Table 6. a-glucosidase activity (mmoles of reducing sugars formed min g f.w.) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 0.003 Mean (C) Eston 0.270 0.284 0.297 0.212 0.185 0.250a Castelluccio 0.220 0.187 0.150 0.130 0.122 0.196b Ustica 0.303 0.292 0.192 0.062 0.060 0.182c Pantelleria 0.309 0.265 0.143 0.059 0.055 0.166d Mean (G) 0.273a 0.257b 0.195c 0.115d 0.105e 48 LSD p50.05 (GC) 0.009 Mean (C) Eston 0.282 0.296 0.197 0.166 0.140 0.216a Castelluccio 0.263 0.191 0.148 0.142 0.125 0.173b Ustica 0.321 0.234 0.153 0.084 0.024 0.163c Pantelleria 0.310 0.240 0.145 0.065 0.025 0.157c Mean (G) 0.294a 0.240b 0.160c 0.114d 0.078e 72 LSD p50.05 (GC) 0.012 Mean (C) Eston 0.299 0.305 0.276 0.208 0.189 0.255a Castelluccio 0.256 0.247 0.215 0.198 0.186 0.220b Ustica 0.338 0.207 0.061 0.041 0.011 0.131c Pantelleria 0.314 0.208 0.058 0.035 0.009 0.132c Mean (G) 0.308a 0.275b 0.152c 0.120d 0.059e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). Padilla & Pugnaire 2007; Munodawafa 2012). Con- germination (Haouari et al. 2013) is directly related to sequently, plant traits related to water uptake are of reserve mobilization, energy production through paramount importance for explaining plant persis- respiration, enzyme and hormonal activity, and tence in Mediterranean-type ecosystems (Valladares dilution of the protoplasm to increase metabolism et al. 2004). The ability to develop extensive root for successful embryonic growth (McDonald 2007). systems contributes to differences among cultivars for The PEG treatment decreased WC in the seeds of the drought tolerance and root length is considered an studied lentil genotypes, as well documented also for important trait in selection of drought resistant other species under similar experimental conditions cultivars (Turner 1997; Abd Allah et al. 2010). (Bajji et al. 2000; Guoxiong et al. 2002;Wuetal. Thus, root morphology and/or growth rate may be 2011; Haouari et al. 2013). Seeds of Castelluccio and instrumental to select drought tolerant varieties Eston had higher WC compared to those of Ustica (Wahbi & Gregory 1995; Malik et al. 2002). In our and Pantelleria indicating that the former genotypes study, total root length decreased with increasing have a more efficient water uptake/control system PEG concentrations more in Pantelleria and Ustica that can be related to the increase in the free proline than in the other two genotypes, indicating a higher content and total soluble carbohydrates, suggesting sensitivity to osmotic stress in these two landraces. that drought tolerance ability of these two last The root length reduction in Pantelleria and Ustica landraces appears to be associated to the accumula- under drought stress may be associated to a reduced tion of osmolytes which improved their water status. cellular division and elongation during germination The osmolyte content increase is one of the self- (Frazer et al. 1990). This hypothesis is supported defense reactions during water stress in seeds and by the results of enzymatic activities involved in the plants protecting the enzyme system. Drought and germination process and by the results of WC. salt stress have been reported to limit the mobilization Water availability is usually the limiting factor for of starchy endosperm reserves in several species, as a the germination of non-dormant seeds, affecting result of inhibition of different enzymatic activities the percentage, speed, and uniformity of emergence (Ashraf & Foolad 2005; Besma & Mounir 2010; (Marcos-Filho 2005; Kaydan & Yagmur 2008). A Biaecka & Kepczyn´ ski 2010). Starch mobilization threshold level of hydration is required for the results from simultaneous activities of a-amylase, synthesis of hydrolytic enzymes which are responsible b-amylase, and a-glucosidase. In germinating seeds, for the hydrolysis of stored substrates. The hydro- starch degradation is initiated by a-amylase (Kaur lyzed products are utilized in seedling tissue synthesis et al. 2005), that produces soluble oligosaccharides and radicle elongation (Canas et al. 2006). In lentil from starch and these are then hydrolyzed by seeds, the role of providing utilizable substrates is b-amylase to liberate maltose. Finally, a-glucosidase taken over mainly by amylases. Inhibition of seed breaks down maltose into glucose, the main respira- Journal of Plant Interactions 361 tolerance of rice (Oryza sativa L.). World Acad Sci Eng tory substrate (Sticklen 2008), with release of the Technol. 68:13781382. energy required for essential metabolic functions Agili S, Nyende B, Ngamau K, Masinde P. 2012. Selection, (Nauriere et al. 1992). Consistently, the activity of yield evaluation, drought tolerance indices of orange- a- and b-amylases in germinating seeds is reduced by flesh sweet potato (Ipomoea batatas Lam) Hybrid water stress (Zeid & Shedeed 2006). Our results Clone. J Nutr Food Sci. 2:138. confirmed that the amylase activities in lentil seeds Ahmad S, Ahmad R, Ashraf MY, Ashraf M, Waraich EA. decreased under PEG induced drought stress, and 2009. Sunflower (Helianthus annuus L.) response to suggested that the variation in stress sensitivity of drought stress at germination and growth stages. Pak J contrasting lentil genotypes may be linked to their Bot. 41:647654. ability to osmoregulate under stress, which cause Albuquerque FMCD, Carvalho NMD. 2003. Effect of type of environmental stress on the emergence of sunflower a strong decrease in WC affecting the hydro- (Helianthus annuus L.), soyabean (Glycine max (L.) lytic enzyme activities, particularly a-amylase and Merril) and maize (Zea mays L.) seeds with different a-glucosidase levels highlighting the greatest decrease levels of vigor. Seed Sci Technol. 31:65467. in the most drought sensitive Ustica and Pantelleria Arjenaki FG, Dehaghi MA, Jabbari R. 2011. Effects of seeds. priming on seed germination of Marigold (Calendula The germination of Ustica and Pantelleria, which officinalis). Adv Environ Biol. 5:276280. are previously identified as NaCl resistant genotypes Ashraf M, Bokhari H, Cristiti SN. 1992. Variation in (Sidari et al. 2007, 2008), was lower than Eston and osmotic adjustment of lentil (Lens culinaris, Medik) in Castelluccio at the same iso-osmotic PEG concentra- response to drought. Acta Bot Neerl. 41:5162. tions. These results indicate that mechanisms mediat- Ashraf M, Foolad MR. 2005. Pre-sowing seed treatment ing drought stress tolerance at germination stage are a shotgun approach to improve germination growth and crop yield under saline and non-saline conditions. different from those that mediate salt stress tolerance Advan Agron. 88:223271. (Munns 2002). Since PEG does not enter to seeds Bajji M, Lutts S, Kinet JM. 2000. Physiological changes after (Khajeh-Hosseini et al. 2003; Mehra et al. 2003), exposure to and recovery from polyethylene glycol- these differences can be specifically associated to induced water deficit in roots and leaves of durum mechanisms that control ion homeostasis and toxicity wheat (Triticum durum Desf.) cultivars differing in (Bohnert et al. 1999). Identifying drought resistant drought resistance. J Plant Physiol. 157:100108. cultivars of lentil at early growth stages is essential to Bartels D, Sunkar R. 2005. Drought and salt tolerance in cultivate this crop in arid and/or semiarid environ- plants. Critical Rev Plant Sci. 24:2358. ments where the survival of other species would be Bates LS, Waldren RP, Teare ID. 1973. Rapid determina- difficult. tion of free proline for water stress studies. Plant Soil. Taken together, these findings suggest that seed 39:205207. Bergmeyer HU, Grabl M, Walter HE. 1983. Enzymes. In: germination, WC, and root length can be used as Bergmeyer HU, Bergmeyer J, Grabl M, editors. traits for rapid selection of drought tolerant cultivars. Methods of enzymatic analysis. Weinheim: Verlag Eston and Castelluccio can be considered as valuable Chemie; p. 126328. drought tolerant germplasm. Our data highlighted an Besma BD, Mounir D. 2010. Salt stress induced changes in opposite response to salt and drought tolerance germination, sugars, starch and enzyme of carbohy- because the two genotypes resulting resistant to drate metabolism in Abelmoschus esculentus L. drought (Eston and Castelluccio) were found salt (Moench.) seeds. Afr J Agric Res. 5:14121418. sensitive (Sidari et al. 2008) whereas the two drought- Bewley JD, Black M. 1994. Seeds: physiology of develop- sensitive genotypes (Ustica and Pantelleria) were ment and germination. New York: Plenum Press. found NaCl tolerant by the same authors. We can Biaecka B, Ke ˛pczyn´ ski J. 2010. Germination, a-, b-amylase and total dehydrogenase activities of amaranthus conclude that all these lentil genotypes could be used caudatus seeds under water stress in the presence of not only in breeding programs to improve tolerance ethephon or gibberellin A . Acta Biol Cracov Ser Bot. to both drought and salinity stress with the aim to 52:712. increase the probability of successful legume estab- Bohnert HJ, Su H, Shen B. 1999. Molecular mechanisms lishments in arid or semiarid environments but also to of salinity tolerance. In: Shinozaki K, Yamaguchi- be cultivated in environments where water scarcity is Shinozaki K, editors. Molecular responses to cold, a frequent constraint. drought, heat and salt stress in higher plants. Austin, TX: Landes Company; p. 2960. Buchanan BB, Gruissem W, Jones RL. 2000. Biochemistry Acknowledgments and molecular biology of plants. Rockville, MD: This research was supported by ‘‘Mediterranea’’ University American Society of Plant Physiologists. of Reggio Calabria-Italy, Programmi di Ricerca Scientifica Canas RA, Canovas FM, Canton FR. 2006. High levels of RDB-2011. asparagines synthetase in hypocotyls of pine seedlings suggest a role of the enzyme in re-allocation of seed scord nitrogen. Planta. 224:8395. References Frazer TE, Silk WK, Rost TL. 1990. Effect of low water Abd Allah AA, Badawy Shimaa A, Zayed BA, ElGohary potential on cortical cell length in growing region of AA. 2010. The role of root system traits in the drought maize roots. Plant Physiol. 93:648651. 362 A. Muscolo et al. Guoxiong C, Krugman T, Fahima T, Korol AB, Nevo E. McDonald MB. 2007. Seed moisture and the equilibrium 2002. Comparative study on morphological and phy- seed moisture content curve. J Seed Technol. 29:718. siological traits related to drought resistance between Mehra V, Tripathi J, Powell AA. 2003. Aerated hydration xeric and mesic Hordeum spontaneum lines in Israel. treatment improves the response of Brassica juncea and Barley Gen Newsl. 32:2233. Brassica campestris seeds to stress during germination. Haouari CC, Nasraoui AH, Carrayol E, Gouia H. 2013. Seed Sci Technol. 31:5770. Variations in a-, b-amylase and a-glycosidase activities Mittler R. 2006. Abiotic stress, the field environment and in two genotypes of wheat under NaCl salinity stress. stress combination. Trends Plant Sci. 11:1519. Afr J Agricult Res. 8:20382043. Munodawafa A. 2012. The effect of rainfall characteristics Hodge A, Berta G, Doussan C, Merchan F, Crespi M. and tillage on sheet erosion and maize grain yield in 2009. Plant root growth, architecture and function. semiarid conditions and granitic sandy soils of Zim- Plant Soil. 321:153187. babwe. Appl Environ Soil Sci. 2012:18. Hohl M, Schopfer P. 1991. Water relations of growing Munns R. 2002. Comparative physiology of salt and water maize coleoptiles. Comparison between mannitol and stress. Plant Cell Environ. 25:239250. polyethylene glycol 6000 as external osmotica for Mwale S, Hamusimbi C, Mwansa K. 2003. Germination, emer- adjusting turgor pressure. Plant Physiol. 95:716722. gence and growth of sunflower (Helianthus annuus L.) in IPCC. 2007. Climate change 2007: synthesis report, con- response to osmotic seed priming. Seed Sci Technol. tribution of working groups I, II and III to the fourth 31:199206. assessment report of the intergovernmental panel on Nauriere C, Doyen C, Thevenot C, Dauffant J. 1992. climate change. In: Pachauri RK, Reisinger A, editors. b-amylase in cereals: study of the maize b-amylase Core writing team. Geneva: IPCC; 104 p. system. Plant Physiol. 100:887893. Jamaati-e-Somarin S, Zabihi-e-Mahmoodabad R. 2011. Okcu G, Kaya MD, Atak M. 2005. Effects of salt and Evaluation of drought tolerance indices of lentil drought stresses on germination and seedling growth varieties. Adv Environ Biol. 5:581584. of pea (Pisum sativum L.). Turk J Agric For. 29:237 Kaur S, Gupta AK, Kaur N. 1998. Gibberellic acid and kinetin partially reverse the effect of water stress on Padilla FM, Pugnaire FI. 2007. Rooting depth and soil germination and seedling growth. Plant Growth Regul. moisture control Mediterranean woody seedling survi- 25:2933. val during drought. Funct Ecol. 21:489495. Kaur S, Gupta AK, Kaur N. 2000. Effect of GA , kinetin Richards RA. 1978. Variation between and within species and indole acetic acid on carbohydrate metabolism in of rapeseed (Brassica campestris and B. napus)in chickpea seedlings germinating under water stress. response to drought stress. III. Physiological and Plant Growth Regul. 30:6170. physicochemical characters. Aust J Agric Res. 29: Kaur R, Liu X, Goerup O, Zhang A, Yuan X, Balk SP, 491501. Schneider MC, Lu ML. 2005. Activation of p 21- Salehi M, Haghnazari A, Shekari F, Faramarzi A. 2008. activated kinase 6 by MAP kinase 6 and p 38 MAP The study of seed yield and seed yield components of kinase. J Bio Chem. 280:33233330. lentil (Lens culinaris Medik) under normal and drought Kaydan D, Yagmur M. 2008. Germination, seedling stress conditions. Pak J Biol Sci. 11:75862. growth and relative water content of shoot in different Shaheen R, Hood-Nowotny RC. 2005. Effect of drought seed sizes of triticale under osmotic stress of water and and salinity on carbon isotope discrimination in wheat NaCl. Afr J Biotechnol. 7:28622868. cultivars. Plant Sci. 168:901909. Khajeh-Hosseini M, Powell AA, Bingham IJ. 2003. The Siahsar BA, Ganjali S, Allahdoo M. 2010. Evaluation of interaction between salinity stress and seed vigour drought tolerance indices and their relationship with during germination of soybean seeds. Seed Sci Tech- grain yield of lentil lines in drought-stressed and nol. 31:715725. irrigated environments. Aust J Basic Appl Sci. Khakwani AA, Dennett MD, Munir M. 2011. Drought 4:43364346. tolerance screening of wheat varieties by inducing Sidari M, Muscolo A, Anastasi U, Preiti G, Santonoceto C. water stress conditions. Songklanakarin J Sci Technol. 2007. Response of four genotypes of lentil to salt stress 33:135142. conditions. Seed Sci Technol. 35:497503. Khourgami A, Maghooli E, Rafiee M, Bitarafan Z. 2012. Sidari M, Santonoceto C, Anastasi U, Preiti G, Muscolo A. Lentil response to supplementary irrigation and plant 2008. Variations in four genotypes of lentil under density under dry farming condition. Int J Sci Adv NaCl-salinity stress. Am J Agric Biol Sci. 3:410416. Technol. 2:5155. Silim SN, Saxena MC, Erskine W. 1993. Adaptation of Kulkarni M, Deshpande U. 2007. In Vitro screening of lentil to the Mediterranean environment. II. Response tomato genotypes for drought resistance using poly- to moisture supply. Exp Agric. 29:2128. ethylene glycol. Afr J Biotechnol. 6:691696. Singh KB, Saxena MC. 1990. Studies on drought tolerance: Larcher W. 1995. Physiological plant ecology. Berlin: Annual report. Aleppo, Syria: ICARDA. Springer. Soleymani A, Hesam M, Shahrajabian H. 2012. Study of Malik AI, Colmer TD, Lambers H, Setter TL, Schorte- cold stress on the germination and seedling stage and meyer M. 2002. Short-term waterlogging has long-term determination of recovery in rice varieties. Int J Biol. effects on the growth and physiology of wheat. New 4:2330. Phytol. 153:225236. Steup M. 1988. Starch degradation. In: Preiss J, editor. The Marcos-Filho JM. 2005. Fisiologia de sementes de plantas cultivadas [Seed physiology of cultivated 480 plants]. biochemistry of plants: a comprehensive treatise. San Piracicaba: FEALQ. Diego, CA: Academic Press; p. 255296. Journal of Plant Interactions 363 Sticklen MB. 2008. Plant genetic engineering for biofuel Wu C, Wang Q, Xie B, Wang Z, Cui J, Hu T. 2011. Effects production: towards affordable cellulosic ethanol. Nat of drought and salt stress on seed germination of three Rev Genet. 9:433443. leguminous species. Afr J Biotechnol. 10:1795417961. Tuberosa R, Salvi S. 2006. Genomics-based approaches to Yemn EW, Willis AJ. 1954. The estimation of carbohy- improve drought tolerance of crops. Trends Plant Sci. drates in plant extracts by anthrone. Biochem J. 11:405412. 57:508514. Turner NC. 1997. Further progress in crop water relations. Zeid IM, Shedeed ZA. 2006. Response of alfalfa to Adv Agron. 58:293338. putrescine treatment under drought stress. Biol Plant. Valladares F, Vilagrosa A, Penuelas J, Ogaya R, Camarero 50:635640. JJ, Corchera L, Siso S, Gil-Pelegrın E. 2004. Estres ´ ´ ´ Zeigler RS, Puckridge DW. 1995. Improving sustainable hı´ drico: ecofisiologı´a y escalas de la sequı´ a [Water productivity in rice based rainfed lowland systems of stress: ecophysiology and scales of drought]. In: South and Southeast Asia. Feeding four billion people: Valladeres F, editor. Ecologı´ a del Bosque Mediterra´ neo the challenge for rice research in the 21st century. en un Mundo Cambiante. Madrid: EGRAF, SA; GeoJournal. 35:307324. p. 163190. Zohary D. 1972. The wild progenitor and place of origin Wahbi A, Gregory PJ. 1995. Growth and development of of the cultivated lentil Lens culinaris. Econ Bot. young roots of barley (Hordeum vulgare L.) genotypes. 26:326332. Ann Bot. 75:533539. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Plant Interactions Taylor & Francis

Effect of PEG-induced drought stress on seed germination of four lentil genotypes

Download PDF
10 pages

Loading next page...
 
/lp/taylor-francis/effect-of-peg-induced-drought-stress-on-seed-germination-of-four-bvc7AzoTfN

References (69)

Publisher
Taylor & Francis
Copyright
© 2013 Taylor & Francis
ISSN
1742-9153
eISSN
1742-9145
DOI
10.1080/17429145.2013.835880
Publisher site
See Article on Publisher Site

Abstract

Journal of Plant Interactions, 2014 Vol. 9, No. 1, 354363, http://dx.doi.org/10.1080/17429145.2013.835880 RESEARCH ARTICLE a a b a c Adele Muscolo *, Maria Sidari , Umberto Anastasi , Carmelo Santonoceto and Albino Maggio Dipartimento di Agraria, Universita` ‘‘Mediterranea’’ di Reggio Calabria, Localita` Feo di Vito, 89126 Reggio Calabria, Italy; Dipartimento di Scienze delle Produzioni Agrarie e Alimentari, Universita` di Catania, Via Valdisavoia 5, 95123 Catania, Italy; Dipartimento di Ingegneria Agraria e Agronomia del Territorio, Universita` di Napoli ‘‘Federico II’’, Via Universita` 100, 80055 Portici, Napoli, Italy (Received 24 July 2013; accepted 13 August 2013) Seeds of four lentil genotypes (Castelluccio, Eston, Pantelleria, and Ustica) were subjected to five levels (0, 10, 15, 18, and 21%) of polyethylene glycol (PEG-6000). Germination percentage, root length, tissue water content (WC), a- and b-amylases, a-glucosidase activities, and osmolyte content were evaluated at 24, 48, and 72 h after starting the germination test. Water stress reduced seed germination percentage, root length, and seedling WC in all cultivars to different extent. The increase in proline content and total soluble sugars was greater for Eston and Castelluccio compared to the other genotypes. The activity of the enzymes involved in the germination process decreased in all cultivars; the activities of a-amylase and a-glucosidase were most negatively affected by osmotic stress, mainly in the drought sensitive Ustica and Pantelleria. Overall, Eston and Castelluccio were able to express greater drought tolerance and consequently could be used as a valuable resource for breeding programs. Keywords: amylase activity; drought; lentil; osmotic stress; proline; seed germination 1. Introduction (Arjenaki et al. 2011). The sequence of events leading to seed germination and root emergence is governed by Worldwide agricultural productivity is subject to water uptake from the external medium (Kaur et al. increasing environmental constraints in the form of 1998; Hodge et al. 2009). Water availability plays a abiotic stresses that adversely influence plants growth significant role in enzymatic reactions, solubilisation and development causing crop failure and decreasing and transportation of metabolites, and also as a average yields more than 50% (Buchanan et al. 2000; reagent in the hydrolytic breakdown of proteins, Bartels & Sunkar 2005; Mittler 2006; Wu et al. 2011). lipids, and carbohydrates in the storage tissues of In semiarid environments where lentil is widespread, germinating seeds (Bewley & Black 1994; Biaecka & unfavorable soil moisture at sowing often conditions Ke ˛pczyn´ ski 2010). Amylase enzymes play an impor- severely seed germination resulting in an irregular tant role during seed germination, hydrolyzing the seedling emergence, which in turn affects the estab- endosperm starch into metabolizable sugars, which lishment of a stand, with negative effects on the yield provide the energy for the growth of roots and shoots (Mwale et al. 2003; Okcu et al. 2005). For these (Nauriere et al. 1992). The activity of such enzymes is reasons, drought tolerance at the germination stage reduced by water stress with negative effects on has specific importance moreover in warm environ- carbohydrate metabolism (Kaur et al. 2000; Zeid & ments most vulnerable to climate change (IPCC Shedeed 2006). 2007). Selection of plants with a better drought tolerance Lentil (Lens culinaris L.), one of the oldest is critical in dry environments (Ashraf et al. 1992; domesticated plants in the world, originated from Tuberosa & Salvi 2006). However, controlled and the near East and central Asia, is traditionally uniformly repeated simulation of drought in the field cultivated in the Mediterranean basin (Zohary cannot be easily achieved (Shaheen & Hood-Nowotny 1972). Seeds of this species are an important source 2005). The slow progress in developing drought- of protein for the human diet and the entire biomass resistant cultivars also reflects the lack of a specific of plant is a valued animal feed. Irrigation generally method for screening the large numbers of genotypes increases lentil yield (Salehi et al. 2008), improving required in breeding for drought (Zeigler & Puckridge seed size, seed yield, biomass yield, and harvest index 1995). Using natural field conditions is difficult be- (Singh & Saxena 1990; Silim et al. 1993; Khourgami cause rainfall can eliminate water deficits. However, in et al. 2012). Thus, the successful crop establishment in semiarid areas depends on the rapid and uniform seed vitro drought-screening methods are facilitating pro- germination, which is strictly associated to the ability gress in our understanding of drought-resistance traits of seeds to germinate under low water availability and in our selection of drought-resistant genotypes. *Corresponding author. Email: [email protected] # 2013 Taylor & Francis Journal of Plant Interactions 355 Richards (1978) suggested germination as a useful to prevent evaporation and kept accordingly to a criterion in screening for water stress tolerance. Khak- completely randomized design in a growth chamber at wani et al. (2011) demonstrated that among the six a temperature of 25918C in the dark with a relative varieties of wheat tested, those who were tolerant to humidity of 70%. Seeds were considered germinated drought during in vitro germination tests were simi- when the radicle had extended for at least 2 mm. The water content (WC) was measured and expressed as a larly tolerant in field conditions. In addition, Agili et al. percentage according to the formula WC (%) (2012) confirmed this finding with experiments on (Fresh Weight  Dry Weight/Fresh Weight)100. sweet potato. Thus, study of the influence of the Root length (cm) was also measured and for each of drought using osmotic solutions is one of the methods four genotypes, five replicates were used. in the evaluation of resistance during the germination phase. Exposure to polyethylene glycol (PEG-6000) solutions has been effectively used to mimic drought 2.2. Enzyme activity stress with limited metabolic interferences as those The activities of a-amylase, b-amylase, and a-gluco- associated to the use of low molecular weight osmo- sidase were determined in the crude extracts of each lytes that can be taken up by the plant (Hohl & cultivar. The seeds of each cultivar and for each PEG Schopfer 1991). PEG-based in vitro screening for treatment (0, 10, 15, 18, and 21%) were homogenized drought tolerance has been proven to be a suitable in a chilled mortar with distilled water 1:4 (w/v) and method to effectively screen large sets of germplasm centrifuged at 14,000 g for 30 min. The supernatants with good accuracy (Kulkarni & Deshpande 2007). were filtered through a single layer of muslin cloth Understanding the biochemical mechanisms in- and were used for a-amylase (EC 3.2.1.1) (Steup volved in plant drought stress tolerance is still a major 1988), b-amylase (EC 3.2.1.2) (Steup 1988), and challenge in biology and agriculture to identify at a-glucosidase (EC 3.2.1.20) (Bergmeyer et al. 1983) early stage suitable traits that would support plant activity determination. breeders in specific selection programs. The main For a-amylase, a mixture of 3 ml soluble starch objective of this study was to evaluate the influence of (2% v/v) and 3 ml extract was incubated for 60 min at drought stress on seeds of the four cultivars of lentil, 308C. After incubation, an equal volume of alkaline which had previously shown to have diverse level of color reagent was added to 1-ml incubation mixture, tolerance to NaCl stress (Sidari et al. 2008), in order mixed and heated for five min in a boiling water bath. to select the best suitable parents for hybridization in The absorbance at 546 nm was measured against a breeding patterns. blank (1 ml H O plus 1 ml alkaline reagent). The standard curve was obtained by using different con- 2. Materials and methods centrations of maltose in the range of 01.5 mmol l . The alkaline color reagent was prepared by dissolving 2.1. Plant material, germination conditions, and 1 g of 3,5-dinitrosalycylic acid in a mixture of 40 ml experimental design 1 N NaOH solution and 30 ml H O. Solid potassium The following lentil cultivars were studied in this sodium tartrate was added and dissolved. The mixture experiment. Two salt stress tolerant landraces ‘Pan- was brought to a final volume of 100 ml (Steup 1988). telleria’ and ‘Ustica’: native and cultivated in the b-amylase was determined as described above but homonymous small islands close to Sicily (Southern soluble starch was replaced by amylopectin. For Italy), a local population ‘Castelluccio di Norcia’: a-glucosidase detection, the assay buffer consisted of cultivated in Umbria region (Central Italy), and a 50 mM Na-acetate, pH 5.2, containing 10 mM CaCl . Canadian commercial variety ‘Eston.’ Seven-month- The substrate was 10 mmol l maltose. The samples old seeds (stored at 20918C and 95% R.U.) of each were incubated for 60 min. The release of glucose was lentil genotype were used. The seeds were selected for followed by measuring the changes in NADPH at size homogeneity, surface-sterilized for 20 min in 30% 340 nm in a coupled enzyme reaction of hexokinase (v/v) H O , rinsed and soaked in distilled water for 1 2 2 and glucose-6-P dehydrogenase. For each treatment, h. For each of four genotypes, five replicates of 50- five replicates were used. seed were placed on a filter paper in 9-cm Petri dishes containing 3 cm of distilled water or 10, 15, 18, and 2.3. Osmolyte content 21% of PEG (MW 6000) concentration correspond- ing to final osmotic potentials of 0.30, 0.51, To detect free proline content samples (0.3 g) includ- 0.58, and 0.80 MPa, respectively. We used 10, ing 5 ml of 3% sulfosalicylic acid were homogenized 15, 18, and 21% of PEG to have an osmotic potential and centrifuged at 3000 rpm for 20 min. The super- comparable to that of NaCl at the concentrations of natant was added to 2 ml of glacial acetic acid with 50, 100, 150, and 200 mM that we tested on seed 2 ml acidic ninhydrin. The mixture was heated at germination of the same cultivars in a previous work 1008C for 25 min. After the liquid was cooled, the (Sidari et al. 2008), in order to evaluate similarity or mixture was added to 4 ml toluene. The absorbance of differences in the metabolic traits of salt and drought the extracts was read at 520 nm (Bates et al. 1973). The resistance. The Petri dishes were sealed with Parafilm total soluble sugars were determined with the 356 A. Muscolo et al. anthrone method (Yemn & Willis 1954). For each length decreased, increasing water stress and time but treatment, five replicates were used. with different extent (Table 2). By increasing PEG concentrations a different behavior among the culti- vars was observed. Eston and Castelluccio showed 2.4. Measurement times and statistical analysis a greater radicle elongation especially at 72 h in comparison to Pantelleria and Ustica. The greatest Root length, water content (WC), enzyme activity, radicle reduction was observed in Ustica and Pantel- and osmolyte content were measured at 24, 48, and leria at 48 and 72 h in presence of PEG at the 72 h after the start of the test. The data were concentrations of 18 and 21%. statistically analyzed separately for each time by a In all cultivars, in the absence of stress, the WC two-way ANOVA according to the adopted experi- increased over time (Table 3). The increase in both mental design combining PEG concentrations and duration and intensity of osmotic stress caused a genotypes. The germination percentage data were gradual decrease in the WC in each cultivar compared previously subjected to arcsine transformation and to controls. The presence of PEG at different con- were reported in tables as untransformed values. The centrations differently affected the cultivars over time. differences between the means were compared by the Increasing the duration of stress and the time, the WC least significant difference (LSD) test (p50.05). decreased in Pantelleria and Ustica and increased in Eston and Castelluccio. The lowest WCs were de- 3. Results tected at 72 h in Ustica and Pantelleria in presence of PEG at the highest (18% and 21%) concentrations. Germination was significantly affected by the osmotic Total soluble sugar content decreased during the potential, by cultivars and their interaction (Table 1). experimental time in Pantelleria and Ustica seeds. On Germination of all cultivars started 24 h after sowing. the contrary, as a consequence of the increasing The final germination percentage of the control (0% drought stress and time, in Eston and Castelluccio, a PEG) reached 100% for each cultivar but with gradual increase in total soluble sugars was observed different time. An increase in PEG stress markedly (Figure 1A) decreased the germination percentage of all cultivars Significant increase in free proline content was compared to their relative controls. Seventy-two also observed in seeds of all genotypes under water hours after sowing, the germination percentage of stress. Eston and Castelluccio under drought condi- Castelluccio and Eston at the highest PEG concen- trations (18% and 21%) was higher than that of tions, accumulated more proline than Pantelleria and Pantelleria and Ustica. Ustica (Figure 1B).The highest amount of proline was The effects of drought stress, cultivars, and their detected in the above two cultivars in presence of interaction were also significant on root length. Root PEG at the concentrations of 18 and 21% at 72 h. Table 1. Germination (%) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD (GC) 3.4 Mean (C) Eston 97 72 33 11 8 44b Castelluccio 98 47 15 4 3 33c Ustica 100 72 47 35 5 52a Pantelleria 100 71 44 35 1 51a Mean (G) 99a 66b 35c 21d 4e 48 LSD (GC) 3.5 Mean (C) Eston 99 80 71 67 44 72a Castelluccio 98 48 35 30 18 46c Ustica 100 76 53 49 27 61b Pantelleria 100 76 57 42 28 60b Mean (G) 99a 70b 54c 47d 29e 72 LSD (GC) 2.3 Mean (C) Eston 100 100 93 91 76 92a Castelluccio 100 71 64 61 47 69b Ustica 100 81 61 51 25 64c Pantelleria 100 81 64 52 28 65c Mean (G) 100a 84b 71c 64d 44e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) were compared according to LSD (p50.05). Journal of Plant Interactions 357 Table 2. Root length (cm) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD (GC) 0.31 Mean (C) Eston 0.69 0.36 0.23 0.17 0.12 0.32a Castelluccio 0.40 0.24 0.14 0.07 0.02 0.17d Ustica 0.52 0.27 0.20 0.15 0.08 0.25c Pantelleria 0.69 0.39 0.24 0.11 0.09 0.30b Mean (G) 0.57a 0.31b 0.20c 0.12d 0.08e 48 LSD (GC) 0.06 Mean (C) Eston 2.51 1.34 1.00 0.68 0.24 1.15a Castelluccio 1.10 0.83 0.76 0.52 0.20 0.68d Ustica 2.03 0.86 0.65 0.34 0.18 0.81c Pantelleria 2.85 0.92 0.77 0.47 0.18 1.04b Mean (G) 2.12a 0.99b 0.80c 0.50d 0.20e 72 LSD (GC) 0.06 Mean (C) Eston 4.31 2.22 1.74 1.02 0.83 2.02a Castelluccio 3.94 1.60 1.35 0.74 0.53 1.63b Ustica 4.15 1.49 1.12 0.42 0.22 1.48d Pantelleria 4.95 1.53 0.87 0.33 0.21 1.58c Mean (G) 4.33a 1.71b 1.27c 0.63d 0.44e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) were compared according to LSD (p50.05). The values of a-amylase, b-amylase, and compared to Ustica and Pantelleria with respect to a-glucosidase activities were constitutively different time and stress level. The activities of these enzymes in the seeds of the four cultivars (Tables 46).The showed a greater decreasing trend in Pantelleria and activity of these enzymes decreased in a dose depen- Ustica in presence of PEG at the concentrations of dent manner, differing among the cultivars. The 18% and 21%, already 24 h after sowing. Among activities of a-, b-amylase, and a-glucosidase in the enzymes involved in the germination process, stressed seeds of Eston and Castelluccio were higher, a-amylase and a-glucosidase were the most negatively Table 3. WC (%) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 2.3 Mean (C) Eston 19 16 17 14 14 16c Castelluccio 19 16 17 15 15 16c Ustica 25 24 21 19 15 21b Pantelleria 38 22 21 22 21 25a Mean (G) 25a 20b 19b 17c 16c 48 LSD p50.05 (GC) 2.5 Mean (C) Eston 39 27 28 27 21 29a Castelluccio 31 28 27 29 21 27b Ustica 33 34 24 20 16 25c Pantelleria 37 37 19 19 17 26c Mean (G) 35a 32b 25c 24c 19d 72 LSD p50.05 (GC) 2.9 Mean (C) Eston 40 34 30 26 24 31a Castelluccio 42 26 25 25 22 28b Ustica 35 31 14 12 10 20c Pantelleria 45 35 13 7 7 21c Mean (G) 40a 32b 20c 17d 16e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). 358 A. Muscolo et al. AB Pantelleria Pantelleria 0 h 0 h Ustica Ustica Eston Eston Castelluccio Castelluccio 0 0 24 h 24 h 0 0 48 h 48 h 0 0 72 h 72 h 0 0 0 5 10 15 20 0 5 10 15 20 PEG concentration % PEG concentration % Figure 1. Total soluble carbohydrates (A) and proline content (B) in Pantelleria, Ustica, Eston, and Castelluccio lentil genotypes seeds in 0, 10, 15, 18, and 21% PEG 6000 at 0, 24, 48, and 72 h. Vertical bars indicate SD (n5). affected by drought stress especially in Ustica and growth stage, stress duration, and severity. Germina- Pantelleria cultivars. tion is the most critical and sensitive stage in the life cycles of plants (Ahmad et al. 2009) and the seeds exposed to unfavorable environmental conditions 4. Discussion such as drought may compromise the subsequent Drought is a multifaceted stress condition that causes seedling establishment (Albuquerque & Carvalho serious crops yield limitations depending on plant 2003; Soleymani et al. 2012). Genetic variability –1 –1 –1 –1 Total soluble carbohydrates [mg g (dw)] Total soluble carbohydrates [mg g (dw)] Total soluble carbohydrates [mg g (dw)] Total solubre carbohydrates [mg g (dw)] –1 –1 –1 Proline [µg g (dw)] Proline [µg g (dw)] –1 Proline [µg g (dw)] Proline [µg g (dw)] Journal of Plant Interactions 359 1 1 Table 4. a-amylase activity (mmoles of reducing sugars formed min g f.w.) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 0.49 Mean (C) Eston 16.12 17.42 17.04 15.49 12.13 15.64c Castelluccio 17.18 16.77 12.41 11.90 11.12 13.88d Ustica 26.10 18.97 19.07 14.47 7.70 17.26b Pantelleria 36.42 31.35 25.28 17.01 7.39 23.49a Mean (G) 24.00a 21.12b 18.45c 14.71d 9.58e 48 LSD p50.05 (GC) 0.21 Mean (C) Eston 16.41 15.31 14.09 13.22 11.13 14.03c Castelluccio 15.52 14.06 13.37 12.06 11.88 13.37d Ustica 27.06 20.09 15.10 10.47 5.69 15.68b Pantelleria 36.05 21.07 13.91 11.22 6.64 17.78a Mean (G) 23.76a 17.63b 14.11c 11.74d 8.84e 72 LSD p50.05 (GC) 0.48 Mean (C) Eston 16.42 16.74 15.50 14.70 12.73 15.22c Castelluccio 12.11 11.97 11.52 11.46 11.06 11.62d Ustica 24.93 22.47 16.40 11.47 7.70 16.59b Pantelleria 36.14 25.20 21.12 18.60 6.73 21.56a Mean (G) 22.40a 19.09b 16.13c 14.06d 9.55e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). within a species offers a valuable tool for studying centrations of PEG reduce the final germination mechanism of drought tolerance. Our results high- percentages of lentil (Siahsar et al. 2010; Jamaati-e- lighted significant differences among the cultivars Somarin & Zabihi-e-Mahmoodabad 2011). In Med- exposed to drought stress with a remarkably de- iterranean semiarid regions, the topsoil WC during creased and delayed germination in Ustica and the dry season is drastically reduced, sometimes to Pantelleria. These results are consistent with those less than 1%, which is very close to the permanent of other studies that have reported that high con- wilting point estimated for xerophytes (Larcher 1995; 1 1 Table 5. b-amylase activity (mmoles of reducing sugars formed min g f.w.) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC). Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 0.09 Mean (C) Eston 0.75 0.65 0.54 0.43 0.38 0.55a Castelluccio 0.69 0.62 0.51 0.44 0.36 0.53a Ustica 1.03 0.55 0.45 0.22 0.19 0.49b Pantelleria 1.06 0.48 0.41 0.24 0.15 0.47b Mean (G) 0.88a 0.58b 0.48c 0.33d 0.27e 48 LSD p50.05 (GC) 0.33 Mean (C) Eston 0.91 0.88 0.84 0.80 0.64 0.81a Castelluccio 0.80 0.71 0.65 0.60 0.56 0.67b Ustica 1.40 0.75 0.45 0.34 0.23 0.63c Pantelleria 1.37 0.73 0.43 0.32 0.22 0.61c Mean (G) 1.12a 0.77b 0.60c 0.51d 0.41e 72 LSD p50.05 (GC) 0.13 Mean (C) Eston 1.17 1.09 0.80 0.73 0.75 0.91a Castelluccio 1.02 0.86 0.72 0.62 0.55 0.75c Ustica 1.55 1.35 0.60 0.45 0.24 0.83b Pantelleria 1.47 1.09 0.52 0.43 0.21 0.75c Mean (G) 1.30a 1.09b 0.66c 0.58d 0.44e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). 360 A. Muscolo et al. 1 1 Table 6. a-glucosidase activity (mmoles of reducing sugars formed min g f.w.) of lentil seeds as affected by genotype (G), PEG concentration (C) factors and their interaction (GC) after 24, 48, and 72 h. Factors PEG concentration (C) Time (h) Genotype (G) 0 10 15 18 21 (%) 24 LSD p50.05 (GC) 0.003 Mean (C) Eston 0.270 0.284 0.297 0.212 0.185 0.250a Castelluccio 0.220 0.187 0.150 0.130 0.122 0.196b Ustica 0.303 0.292 0.192 0.062 0.060 0.182c Pantelleria 0.309 0.265 0.143 0.059 0.055 0.166d Mean (G) 0.273a 0.257b 0.195c 0.115d 0.105e 48 LSD p50.05 (GC) 0.009 Mean (C) Eston 0.282 0.296 0.197 0.166 0.140 0.216a Castelluccio 0.263 0.191 0.148 0.142 0.125 0.173b Ustica 0.321 0.234 0.153 0.084 0.024 0.163c Pantelleria 0.310 0.240 0.145 0.065 0.025 0.157c Mean (G) 0.294a 0.240b 0.160c 0.114d 0.078e 72 LSD p50.05 (GC) 0.012 Mean (C) Eston 0.299 0.305 0.276 0.208 0.189 0.255a Castelluccio 0.256 0.247 0.215 0.198 0.186 0.220b Ustica 0.338 0.207 0.061 0.041 0.011 0.131c Pantelleria 0.314 0.208 0.058 0.035 0.009 0.132c Mean (G) 0.308a 0.275b 0.152c 0.120d 0.059e Note: At each time (h), means followed by the same letter, within each factor, are not significantly different according to LSD (p50.05). Means of interaction (GC) are compared according to LSD (p50.05). Padilla & Pugnaire 2007; Munodawafa 2012). Con- germination (Haouari et al. 2013) is directly related to sequently, plant traits related to water uptake are of reserve mobilization, energy production through paramount importance for explaining plant persis- respiration, enzyme and hormonal activity, and tence in Mediterranean-type ecosystems (Valladares dilution of the protoplasm to increase metabolism et al. 2004). The ability to develop extensive root for successful embryonic growth (McDonald 2007). systems contributes to differences among cultivars for The PEG treatment decreased WC in the seeds of the drought tolerance and root length is considered an studied lentil genotypes, as well documented also for important trait in selection of drought resistant other species under similar experimental conditions cultivars (Turner 1997; Abd Allah et al. 2010). (Bajji et al. 2000; Guoxiong et al. 2002;Wuetal. Thus, root morphology and/or growth rate may be 2011; Haouari et al. 2013). Seeds of Castelluccio and instrumental to select drought tolerant varieties Eston had higher WC compared to those of Ustica (Wahbi & Gregory 1995; Malik et al. 2002). In our and Pantelleria indicating that the former genotypes study, total root length decreased with increasing have a more efficient water uptake/control system PEG concentrations more in Pantelleria and Ustica that can be related to the increase in the free proline than in the other two genotypes, indicating a higher content and total soluble carbohydrates, suggesting sensitivity to osmotic stress in these two landraces. that drought tolerance ability of these two last The root length reduction in Pantelleria and Ustica landraces appears to be associated to the accumula- under drought stress may be associated to a reduced tion of osmolytes which improved their water status. cellular division and elongation during germination The osmolyte content increase is one of the self- (Frazer et al. 1990). This hypothesis is supported defense reactions during water stress in seeds and by the results of enzymatic activities involved in the plants protecting the enzyme system. Drought and germination process and by the results of WC. salt stress have been reported to limit the mobilization Water availability is usually the limiting factor for of starchy endosperm reserves in several species, as a the germination of non-dormant seeds, affecting result of inhibition of different enzymatic activities the percentage, speed, and uniformity of emergence (Ashraf & Foolad 2005; Besma & Mounir 2010; (Marcos-Filho 2005; Kaydan & Yagmur 2008). A Biaecka & Kepczyn´ ski 2010). Starch mobilization threshold level of hydration is required for the results from simultaneous activities of a-amylase, synthesis of hydrolytic enzymes which are responsible b-amylase, and a-glucosidase. In germinating seeds, for the hydrolysis of stored substrates. The hydro- starch degradation is initiated by a-amylase (Kaur lyzed products are utilized in seedling tissue synthesis et al. 2005), that produces soluble oligosaccharides and radicle elongation (Canas et al. 2006). In lentil from starch and these are then hydrolyzed by seeds, the role of providing utilizable substrates is b-amylase to liberate maltose. Finally, a-glucosidase taken over mainly by amylases. Inhibition of seed breaks down maltose into glucose, the main respira- Journal of Plant Interactions 361 tolerance of rice (Oryza sativa L.). World Acad Sci Eng tory substrate (Sticklen 2008), with release of the Technol. 68:13781382. energy required for essential metabolic functions Agili S, Nyende B, Ngamau K, Masinde P. 2012. Selection, (Nauriere et al. 1992). Consistently, the activity of yield evaluation, drought tolerance indices of orange- a- and b-amylases in germinating seeds is reduced by flesh sweet potato (Ipomoea batatas Lam) Hybrid water stress (Zeid & Shedeed 2006). Our results Clone. J Nutr Food Sci. 2:138. confirmed that the amylase activities in lentil seeds Ahmad S, Ahmad R, Ashraf MY, Ashraf M, Waraich EA. decreased under PEG induced drought stress, and 2009. Sunflower (Helianthus annuus L.) response to suggested that the variation in stress sensitivity of drought stress at germination and growth stages. Pak J contrasting lentil genotypes may be linked to their Bot. 41:647654. ability to osmoregulate under stress, which cause Albuquerque FMCD, Carvalho NMD. 2003. Effect of type of environmental stress on the emergence of sunflower a strong decrease in WC affecting the hydro- (Helianthus annuus L.), soyabean (Glycine max (L.) lytic enzyme activities, particularly a-amylase and Merril) and maize (Zea mays L.) seeds with different a-glucosidase levels highlighting the greatest decrease levels of vigor. Seed Sci Technol. 31:65467. in the most drought sensitive Ustica and Pantelleria Arjenaki FG, Dehaghi MA, Jabbari R. 2011. Effects of seeds. priming on seed germination of Marigold (Calendula The germination of Ustica and Pantelleria, which officinalis). Adv Environ Biol. 5:276280. are previously identified as NaCl resistant genotypes Ashraf M, Bokhari H, Cristiti SN. 1992. Variation in (Sidari et al. 2007, 2008), was lower than Eston and osmotic adjustment of lentil (Lens culinaris, Medik) in Castelluccio at the same iso-osmotic PEG concentra- response to drought. Acta Bot Neerl. 41:5162. tions. These results indicate that mechanisms mediat- Ashraf M, Foolad MR. 2005. Pre-sowing seed treatment ing drought stress tolerance at germination stage are a shotgun approach to improve germination growth and crop yield under saline and non-saline conditions. different from those that mediate salt stress tolerance Advan Agron. 88:223271. (Munns 2002). Since PEG does not enter to seeds Bajji M, Lutts S, Kinet JM. 2000. Physiological changes after (Khajeh-Hosseini et al. 2003; Mehra et al. 2003), exposure to and recovery from polyethylene glycol- these differences can be specifically associated to induced water deficit in roots and leaves of durum mechanisms that control ion homeostasis and toxicity wheat (Triticum durum Desf.) cultivars differing in (Bohnert et al. 1999). Identifying drought resistant drought resistance. J Plant Physiol. 157:100108. cultivars of lentil at early growth stages is essential to Bartels D, Sunkar R. 2005. Drought and salt tolerance in cultivate this crop in arid and/or semiarid environ- plants. Critical Rev Plant Sci. 24:2358. ments where the survival of other species would be Bates LS, Waldren RP, Teare ID. 1973. Rapid determina- difficult. tion of free proline for water stress studies. Plant Soil. Taken together, these findings suggest that seed 39:205207. Bergmeyer HU, Grabl M, Walter HE. 1983. Enzymes. In: germination, WC, and root length can be used as Bergmeyer HU, Bergmeyer J, Grabl M, editors. traits for rapid selection of drought tolerant cultivars. Methods of enzymatic analysis. Weinheim: Verlag Eston and Castelluccio can be considered as valuable Chemie; p. 126328. drought tolerant germplasm. Our data highlighted an Besma BD, Mounir D. 2010. Salt stress induced changes in opposite response to salt and drought tolerance germination, sugars, starch and enzyme of carbohy- because the two genotypes resulting resistant to drate metabolism in Abelmoschus esculentus L. drought (Eston and Castelluccio) were found salt (Moench.) seeds. Afr J Agric Res. 5:14121418. sensitive (Sidari et al. 2008) whereas the two drought- Bewley JD, Black M. 1994. Seeds: physiology of develop- sensitive genotypes (Ustica and Pantelleria) were ment and germination. New York: Plenum Press. found NaCl tolerant by the same authors. We can Biaecka B, Ke ˛pczyn´ ski J. 2010. Germination, a-, b-amylase and total dehydrogenase activities of amaranthus conclude that all these lentil genotypes could be used caudatus seeds under water stress in the presence of not only in breeding programs to improve tolerance ethephon or gibberellin A . Acta Biol Cracov Ser Bot. to both drought and salinity stress with the aim to 52:712. increase the probability of successful legume estab- Bohnert HJ, Su H, Shen B. 1999. Molecular mechanisms lishments in arid or semiarid environments but also to of salinity tolerance. In: Shinozaki K, Yamaguchi- be cultivated in environments where water scarcity is Shinozaki K, editors. Molecular responses to cold, a frequent constraint. drought, heat and salt stress in higher plants. Austin, TX: Landes Company; p. 2960. Buchanan BB, Gruissem W, Jones RL. 2000. Biochemistry Acknowledgments and molecular biology of plants. Rockville, MD: This research was supported by ‘‘Mediterranea’’ University American Society of Plant Physiologists. of Reggio Calabria-Italy, Programmi di Ricerca Scientifica Canas RA, Canovas FM, Canton FR. 2006. High levels of RDB-2011. asparagines synthetase in hypocotyls of pine seedlings suggest a role of the enzyme in re-allocation of seed scord nitrogen. Planta. 224:8395. References Frazer TE, Silk WK, Rost TL. 1990. Effect of low water Abd Allah AA, Badawy Shimaa A, Zayed BA, ElGohary potential on cortical cell length in growing region of AA. 2010. The role of root system traits in the drought maize roots. Plant Physiol. 93:648651. 362 A. Muscolo et al. Guoxiong C, Krugman T, Fahima T, Korol AB, Nevo E. McDonald MB. 2007. Seed moisture and the equilibrium 2002. Comparative study on morphological and phy- seed moisture content curve. J Seed Technol. 29:718. siological traits related to drought resistance between Mehra V, Tripathi J, Powell AA. 2003. Aerated hydration xeric and mesic Hordeum spontaneum lines in Israel. treatment improves the response of Brassica juncea and Barley Gen Newsl. 32:2233. Brassica campestris seeds to stress during germination. Haouari CC, Nasraoui AH, Carrayol E, Gouia H. 2013. Seed Sci Technol. 31:5770. Variations in a-, b-amylase and a-glycosidase activities Mittler R. 2006. Abiotic stress, the field environment and in two genotypes of wheat under NaCl salinity stress. stress combination. Trends Plant Sci. 11:1519. Afr J Agricult Res. 8:20382043. Munodawafa A. 2012. The effect of rainfall characteristics Hodge A, Berta G, Doussan C, Merchan F, Crespi M. and tillage on sheet erosion and maize grain yield in 2009. Plant root growth, architecture and function. semiarid conditions and granitic sandy soils of Zim- Plant Soil. 321:153187. babwe. Appl Environ Soil Sci. 2012:18. Hohl M, Schopfer P. 1991. Water relations of growing Munns R. 2002. Comparative physiology of salt and water maize coleoptiles. Comparison between mannitol and stress. Plant Cell Environ. 25:239250. polyethylene glycol 6000 as external osmotica for Mwale S, Hamusimbi C, Mwansa K. 2003. Germination, emer- adjusting turgor pressure. Plant Physiol. 95:716722. gence and growth of sunflower (Helianthus annuus L.) in IPCC. 2007. Climate change 2007: synthesis report, con- response to osmotic seed priming. Seed Sci Technol. tribution of working groups I, II and III to the fourth 31:199206. assessment report of the intergovernmental panel on Nauriere C, Doyen C, Thevenot C, Dauffant J. 1992. climate change. In: Pachauri RK, Reisinger A, editors. b-amylase in cereals: study of the maize b-amylase Core writing team. Geneva: IPCC; 104 p. system. Plant Physiol. 100:887893. Jamaati-e-Somarin S, Zabihi-e-Mahmoodabad R. 2011. Okcu G, Kaya MD, Atak M. 2005. Effects of salt and Evaluation of drought tolerance indices of lentil drought stresses on germination and seedling growth varieties. Adv Environ Biol. 5:581584. of pea (Pisum sativum L.). Turk J Agric For. 29:237 Kaur S, Gupta AK, Kaur N. 1998. Gibberellic acid and kinetin partially reverse the effect of water stress on Padilla FM, Pugnaire FI. 2007. Rooting depth and soil germination and seedling growth. Plant Growth Regul. moisture control Mediterranean woody seedling survi- 25:2933. val during drought. Funct Ecol. 21:489495. Kaur S, Gupta AK, Kaur N. 2000. Effect of GA , kinetin Richards RA. 1978. Variation between and within species and indole acetic acid on carbohydrate metabolism in of rapeseed (Brassica campestris and B. napus)in chickpea seedlings germinating under water stress. response to drought stress. III. Physiological and Plant Growth Regul. 30:6170. physicochemical characters. Aust J Agric Res. 29: Kaur R, Liu X, Goerup O, Zhang A, Yuan X, Balk SP, 491501. Schneider MC, Lu ML. 2005. Activation of p 21- Salehi M, Haghnazari A, Shekari F, Faramarzi A. 2008. activated kinase 6 by MAP kinase 6 and p 38 MAP The study of seed yield and seed yield components of kinase. J Bio Chem. 280:33233330. lentil (Lens culinaris Medik) under normal and drought Kaydan D, Yagmur M. 2008. Germination, seedling stress conditions. Pak J Biol Sci. 11:75862. growth and relative water content of shoot in different Shaheen R, Hood-Nowotny RC. 2005. Effect of drought seed sizes of triticale under osmotic stress of water and and salinity on carbon isotope discrimination in wheat NaCl. Afr J Biotechnol. 7:28622868. cultivars. Plant Sci. 168:901909. Khajeh-Hosseini M, Powell AA, Bingham IJ. 2003. The Siahsar BA, Ganjali S, Allahdoo M. 2010. Evaluation of interaction between salinity stress and seed vigour drought tolerance indices and their relationship with during germination of soybean seeds. Seed Sci Tech- grain yield of lentil lines in drought-stressed and nol. 31:715725. irrigated environments. Aust J Basic Appl Sci. Khakwani AA, Dennett MD, Munir M. 2011. Drought 4:43364346. tolerance screening of wheat varieties by inducing Sidari M, Muscolo A, Anastasi U, Preiti G, Santonoceto C. water stress conditions. Songklanakarin J Sci Technol. 2007. Response of four genotypes of lentil to salt stress 33:135142. conditions. Seed Sci Technol. 35:497503. Khourgami A, Maghooli E, Rafiee M, Bitarafan Z. 2012. Sidari M, Santonoceto C, Anastasi U, Preiti G, Muscolo A. Lentil response to supplementary irrigation and plant 2008. Variations in four genotypes of lentil under density under dry farming condition. Int J Sci Adv NaCl-salinity stress. Am J Agric Biol Sci. 3:410416. Technol. 2:5155. Silim SN, Saxena MC, Erskine W. 1993. Adaptation of Kulkarni M, Deshpande U. 2007. In Vitro screening of lentil to the Mediterranean environment. II. Response tomato genotypes for drought resistance using poly- to moisture supply. Exp Agric. 29:2128. ethylene glycol. Afr J Biotechnol. 6:691696. Singh KB, Saxena MC. 1990. Studies on drought tolerance: Larcher W. 1995. Physiological plant ecology. Berlin: Annual report. Aleppo, Syria: ICARDA. Springer. Soleymani A, Hesam M, Shahrajabian H. 2012. Study of Malik AI, Colmer TD, Lambers H, Setter TL, Schorte- cold stress on the germination and seedling stage and meyer M. 2002. Short-term waterlogging has long-term determination of recovery in rice varieties. Int J Biol. effects on the growth and physiology of wheat. New 4:2330. Phytol. 153:225236. Steup M. 1988. Starch degradation. In: Preiss J, editor. The Marcos-Filho JM. 2005. Fisiologia de sementes de plantas cultivadas [Seed physiology of cultivated 480 plants]. biochemistry of plants: a comprehensive treatise. San Piracicaba: FEALQ. Diego, CA: Academic Press; p. 255296. Journal of Plant Interactions 363 Sticklen MB. 2008. Plant genetic engineering for biofuel Wu C, Wang Q, Xie B, Wang Z, Cui J, Hu T. 2011. Effects production: towards affordable cellulosic ethanol. Nat of drought and salt stress on seed germination of three Rev Genet. 9:433443. leguminous species. Afr J Biotechnol. 10:1795417961. Tuberosa R, Salvi S. 2006. Genomics-based approaches to Yemn EW, Willis AJ. 1954. The estimation of carbohy- improve drought tolerance of crops. Trends Plant Sci. drates in plant extracts by anthrone. Biochem J. 11:405412. 57:508514. Turner NC. 1997. Further progress in crop water relations. Zeid IM, Shedeed ZA. 2006. Response of alfalfa to Adv Agron. 58:293338. putrescine treatment under drought stress. Biol Plant. Valladares F, Vilagrosa A, Penuelas J, Ogaya R, Camarero 50:635640. JJ, Corchera L, Siso S, Gil-Pelegrın E. 2004. Estres ´ ´ ´ Zeigler RS, Puckridge DW. 1995. Improving sustainable hı´ drico: ecofisiologı´a y escalas de la sequı´ a [Water productivity in rice based rainfed lowland systems of stress: ecophysiology and scales of drought]. In: South and Southeast Asia. Feeding four billion people: Valladeres F, editor. Ecologı´ a del Bosque Mediterra´ neo the challenge for rice research in the 21st century. en un Mundo Cambiante. Madrid: EGRAF, SA; GeoJournal. 35:307324. p. 163190. Zohary D. 1972. The wild progenitor and place of origin Wahbi A, Gregory PJ. 1995. Growth and development of of the cultivated lentil Lens culinaris. Econ Bot. young roots of barley (Hordeum vulgare L.) genotypes. 26:326332. Ann Bot. 75:533539.

Journal

Journal of Plant Interactions – Taylor & Francis

Published: Jan 2, 2014

Keywords: amylase activity; drought; lentil; osmotic stress; proline; seed germination

There are no references for this article.