Effects of salinity and phosphate on ion distribution in lupin leafletsTreeby, Michael T.; Steveninck, Reinhard F. M.
doi: 10.1111/j.1399-3054.1988.tb00604.xpmid: N/A
Lupin (Lupinus luteus L. cv. Weiko III) were grown in nutrient solution over a range of inorganic phosphate (Pi) concentrations, with or without 50 mM NaCl. Plants with high Pi (2 mM) and salt showed progressive leaf necrosis and had higher concentrations of total phosphate than plants grown with high Pi alone. Most of the extra total phosphate in salt treated plants was in the Pi form. Pi supply did not influence Na+, K+ or Cl− concentrations in epidermal vacuoles or mesophyll cells. However, epidermal vacuoles accumulated more monovalent cations (Na+ and K+) than Cl−, and in vacuoles of plants grown with 0.1 mM Pi additional Pi was accumulated, possibly to maintain charge balance. Plants grown with 2 mM Pi did not accumulate additional Pi in epidermal vacuoles, but showed higher phosphorus levels in cell walls. It is suggested that at moderate phosphorus concentrations Pi plays a role in epidermal osmotic adjustment, possibly explaining the beneficial role of additional phosphorus on salt stressed plants. At high Pi supply with salt, Pi does not contribute to osmotic adjustment and instead accumulates in cell walls. However, the cause of leaf damage under conditions of high phosphorus supply and salinity is still not entirely clear.
Germination of annual celery (Apium graveolens) seeds: Inhibition by paclobutrazol and its reversal by gibberellins and benzyladeninePressman, Etan; Shaked, Rachel
doi: 10.1111/j.1399-3054.1988.tb00605.xpmid: N/A
Plants of annual celery (Apium graveolens L.) were treated with paclobutrazol during anthesis. Seeds collected from the treated plants showed a marked reduction in germination in light and failed to germinate in the dark. Application of GA4/7 to the imbibition solution reversed the inhibitory effect of paclobutrazol while gibberellic acid (GA3) was ineffective. Benzyladenine (BA) interaction with GA4/7 was light and concentration‐dependent. At relatively low concentrations in the dark there was a synergistic effect, but at higher concentrations, especially in the light, BA, antagonized the GA4/7 effect. Seedlings emerging from the seeds from paclobutrazol‐treated plants were only slightly shortened. It is suggested that paclobutrazol applied to the mother plants inhibited the biosynthesis of endogenous GAs, which normally enable the germination of annual seeds under unfavorable conditions. Exogenously applied GA4/7 fulfills the function of the absent endogenous GAs.
Combined effect of light and temperature on triacylglycerol accumulation in Dicranum elongatumKarunen, Pirjo; Hakala, Kaija; Mikola, Heikki
doi: 10.1111/j.1399-3054.1988.tb00607.xpmid: N/A
In the subarctic moss Dicranum elongatum Schleich & Schwaegr., the level of total lipids and triacylglycerols (TAG) was high in late winter and spring and low in autumn and winter. Four‐week exposure of field material to continuous light (135μmol m−2s−1) at 1°C resulted in a considerable increase in the amount of TAG in the autumn material acclimated to low temperatures and rhythmic light in the field. In contrast, the same treatment did not cause any increase in TAG in the spring material, acclimated to low temperatures and continuous light in the field. Results from experiments, in which moss cultivated for 4 months at 9°C on 12‐h photoperiods (135μmol m−2s−1) was kept for 3 weeks at low temperatures (9°C and −3°C) either in continuous light (135 or 70 μmol m−2s−1) or with 12‐h photoperiods (135 μmol m−2s−1), indicated that the TAG level was higher at higher light intensity. At 9°C it was also higher in continuous light of both intensities than in rhythmic light. These results strongly suggest that decreasing irradiance and decreasing daylength limits the accumulation of TAG in D. elongatum during autumn in the subarctic.
Characterization and partial purification of multiple electron transport activities in plasma membranes from maize (Zea mays) rootsLuster, Douglas G.; Buckhout, Thomas J.
doi: 10.1111/j.1399-3054.1988.tb00608.xpmid: N/A
The plasma membrane of eukaryotic cells contains endogenous, integral electron transport proteins. In the maize (Zea mays L. cv. Golden Cross Bantam) root plasma membrane, these activities include NAD(P)H‐ferricyanide reductase. NAD(P)H‐duroquinone reductase (1.6.5.1) and NAD(P)H‐ascorbate free‐radical reductase (EC 1.6.5.4). Differences in degree of stimulation upon vesicle rupture with detergent and in specificities for pyridine nucleotides suggest that these activities constitute distinct components in the membranes. Solubilization of reductase activities was examined using Triton X‐100 over a wide range of retergent‐to‐protein ratios. The Triton‐solubilized enzymes were purified using dye‐ligand affinity chromatography on Cibacron blue 3G‐A agarose utilizing biospecific elution with NADH. Resolution of the redox activities was accomplished upon differential elution with 0.1.1.0 and 10 mM NADH. The distinctive characteristics of the enzymes and the differential chromatographic behavior of the respective activities provided evidence for the presence of separate enzymatic redox components in maize root plasma membranes with implications for an electron transfer chain.
Identification and quantitation of gibberellins in fruits of Lycopersicon esculentum, and their relationship to fruit size in L. esculentum and L. pimpinellfoliumBohner, J.; Hedden, P.; Bora‐Haber, E.; Bangerth, F.
doi: 10.1111/j.1399-3054.1988.tb00609.xpmid: N/A
GA1, GA8, GA17, GA19, GA20 and GA29 were identified by combined gas chromatography‐mass spectrometgry (GC‐MS) in immature seeds and pericarp of Lycopersicon esculentum Mill. (tomato). Higher levels of these GAs were present in the seeds than in the pericarp; seeds in addition contained GA15, GA24, GA25, and GA44. Fruits of the Lycopersicon pimpinellifolium Mill. mutant I were smaller and contained lower GA1 concentrations, but higher GA20 concentrations, than those of mutants III and IV. In contrast, differences in fruit size in L. esculentum due to position on the truss did not correlate with GA1 concentration in either the pericarp or seeds.
Adventitious bud production on explants of Begonia×hiemalis depends on the developmental state of the donor plantSimmonds, John; Nelson, Sherman D.
doi: 10.1111/j.1399-3054.1988.tb00611.xpmid: N/A
In vitro responses can be influenced by the developmental status of the donor plant tissue. The effects of the donor plant photoperiod and the developmental stage of the plant on organogenesis of petiole explants of Begonia×hiemalis cv. Schwabenland Pink are reported. Long day plants had progressively more branches, total stem length, leaf area, and branch and shoot mass. In short days, flowering was earlier and a greater proportion of dry weight accumulation was allocated to reproductive structures. Similar explant responses were obtained from all developmental stages until flowering was well advanced in short days and then the regenerative capacity diminished. Primary measurements of donor leaves (length, area and weight) at the time of explant removal were not well correlated with adventitious bud production. Loss of regeneration was not determined by tissue or plant age but was associated with the progressive development of flowers. Thus the donor plant photoperiod only indirectly affected bud production. Organogenesis decreased with duration of short days but increased in long days and thus both the duration of the multiplication phase and the intensity of the in vitro response was enhanced by maintaining donor plants in long days.
Induction of secondary dormancy in sunflower seeds by high temperature. Possible involvement of ethylene biosynthesisCorbineau, F.; Rudnicki, R. M.; Côme, D.
doi: 10.1111/j.1399-3054.1988.tb00612.xpmid: N/A
High temperature (45°C) inhibits seed germinition and seedling sunflower (Helianthus annuus L. cv. Mirasol). Treatment of imbibed seeds at 45°C for more than 48 h induces a secondary dormancy, which is associated with progressive decrease of germination ability at optimal temperature (25°C) as well as with abnormal seedling growth. Ethylene (55μl l−1) and 2‐chloroethylphosphonic acid (ethephon) (2.5 mM) improve germination of thermodormant seeds at 25°C. but the abnormal growth of the seedlings remains. O2‐enriched atmosphere and dry storage improve germination and normal seedling growth. The induction of thermodormancy in sunflower seeds seems associated with loss of their ability to convert 1‐aminocyclopropane‐1‐carboxylic acid (ACC) to ethylene. Possible effects of high temperature on membranes and ethylene forming enzyme (EFE) are discussed.
Effect of oxygen concentration on the senescence and energy metabolism of cut carnation flowersTrippi, Victorio S.; Paulin, André; Pradet, Alain
doi: 10.1111/j.1399-3054.1988.tb00613.xpmid: N/A
The effect of O2 concentration on energy metabolism and senescence has been studied in cut flowers of Dianthus caryophyllus L. cv. Scania. As compared to the control (21% O2), 5% O2 delays flower senescence as well as decay of nucleotide level and AEC (adenylate energy charge). An atmosphere of 100% O2 accelerates senescence as well as the decrease of nucleotide level and AEC. While anoxia brings about a faster decrease of ATP and AEC than of total nucleotides, hyperoxia brings about a faster decrease in adenyl nucleotides than in ATP and AEC values. Petal oxygen uptake is over 90% of the maximal value under 4% O2 and saturates at 10% O2. The development of senescence is dicussed as a two phase process (first phase‐progressive and second phase‐catastrophic) triggered by the action of hyperoxia, first on the system for energy utilization and later on the system for energy production, the degradation of which seems to be linked with increase in membrane permeability and withering.