Plant Signaling & Behavior

Liu, Qianwei; Gao, Tengteng; Liu, Wenxuan; Liu, Yusong; Zhao, Yongjuan; Liu, Yuerong; Li, Wenjing; Ding, Ke; Ma, Fengwang; Li, Chao

doi: 10.1080/15592324.2020.1827782pmid: 33040671

Dopamine (3-hydroxytyramine or 3,4-dihydroxyphenethylamine) has many functions in animals, but also shows several other functions in plants. Since the discovery of dopamine in plants in 1968, many studies have provided insight into physiological and biochemical functions, and stress responses of this molecule. In this review, we describe the biosynthesis of dopamine, as well as its role in plant growth and development. In addition, endogenous or exogenously applied dopamine improved the tolerance against several abiotic stresses, such as drought, salt, and nutrient stress. There are also several studies that dopamine contributes to the plant immune response against plant disease. Dopamine affects the expression of many abiotic stresses related genes, which highlights its role as a multi-regulatory molecule and can coordinate many aspects of plant development. Our review emphasized the effects of dopamine against environmental stresses along with future research directions, which will help improve the yield of eco-friendly crops and ensure food security.

Marler, Thomas E.; Griffith, M. Patrick; Krishnapillai, Murukesan V.

doi: 10.1080/15592324.2020.1830237pmid: 33073692

Growth dynamics of pachycaulous stems of arborescent cycad plants are not well understood, and most observations have been made in cultivated garden plants. We studied Cycas micronesica plants in Guam, Tinian, and Yap to understand the influences of geography, plant size, sex, and herbivory on stem growth. We also determined the changes in demography of Guam’s population after 15 years of damage by non-native insect herbivores. The height increment (HI) was similar for plants within the height range from 100 cm to more than 600 cm, so the relative growth rate declined with height. Female tree HI was 68% of male tree HI, and Yap tree HI was 87% of Guam tree HI. Chronic herbivory by non-native insect herbivores caused a mean 44% decline in HI. Plants in managed gardens grew more rapidly than plants in a wild habitat. The HI was used to estimate that Guam has experienced a complete loss of ≈70 y of demographic depth resulting from the selective mortality of small plants since 2005. When future conservation interventions successfully mitigate the ubiquitous biological threats, our HI may be useful for empirically quantifying recovery of plant health.

Kaiwen, Guo; Zisong, Xu; Yuze, Huo; Qi, Sun; Yue, Wang; Yanhui, Che; Jiechen, Wang; Wei, Li; Huihui, Zhang

doi: 10.1080/15592324.2020.1832373pmid: 33073686

In order to explore the main limiting factors affecting the growth and physiological function of alfalfa under salt and alkali stress, the effect of the salt and alkali stress on the growth and physiological function of alfalfa was studied. The results showed that effects of the excessive salt concentration (100 and 200 mM) on the growth and physiological characteristics were significantly greater than that of pH (7.0 and 9.0). Under 100 mM salt stress, there was no significant difference in the growth and photosynthetic function between pH 9.0 and pH 7.0. Under the 200 mM salt concentration the absorption of Na+ by alfalfa treated at the pH 9.0 did not increase significantly compared with absorption at the pH 7.0. However, the higher pH directly reduced the root activity, leaf’s water content, and N-P-K content also decreased significantly. The PSII and PSI activities decreased with increasing the salt concentration, especially the damage degree of PSI. Although the photoinhibition of PSII was not significant, PSII donor and electron transfer from the Q A to Q B of the PSII receptor sides was inhibited. In a word, alfalfa showed relatively strong salt tolerance capacity, at the 100 mM salt concentration, even when the pH reached 9.0. Thus, the effect on the growth and photosynthetic function was not significant. However, at 200 mM salt concentration, pH 9.0 treatment caused damage to root system and the photosynthetic function in leaves of alfalfa was seriously injured.

Frongia, Francesca; Forti, Luca; Arru, Laura

doi: 10.1080/15592324.2020.1828674pmid: 33048612

Life evolved in an acoustic world. Sound is perceived in different ways by the species that inhabit the Planet. Among organisms, also some algal species seem to respond to sound stimuli with increased cell growth and productivity. The purpose of this Short Communication is to provide an overview of the current literature about various organisms and sound, with particular attention to algal organisms, which, when subjected to sound applications, can change their metabolism accordingly.

Wenjing, Wang; Chen, Qingbin; Singh, Prashant Kumar; Huang, Yuanyuan; Pei, Dongli

doi: 10.1080/15592324.2020.1816321pmid: 32936726

The role of Heat Shock Transcription Factor 6 (HSFA6a & HSFA6b) in response to abiotic stresses such as ABA, drought, salinity, drought, and osmotic stress is individually well established. Unfortunately, the functional redundancy between the HSFA6a and HSFA6b as well as the consequences of simultaneous editing of both in response to aforementioned stresses remains elusive. Therefore, this study was designed with the aim of addressing whether there is any functional redundancy between HSFA6a and HSFA6b as well as to decipher their role in abiotic stresses tolerance in Arabidopsis thaliana, by using the CRISPR-Cas9. We have generated the single (hsfa6a and hsfa6b) as well as double mutants (hsfa6a/hsfa6b-1 and hsfa6a/hsfa6b-2) of HSFA6a and HSFA6b with higher frequencies of deletion, insertion, and substitution. The phenotypic characterization of generated double and single mutants under abiotic stresses such as ABA, mannitol, and NaCl identified double mutants more tolerant to subjected abiotic stresses than those of their single mutants. It warrants mentioning that we have identified that HSFA6a and HSFA6b also involved in other major ABA responses, including ABA-inhibited seed germination, stomatal movement, and water loss. In addition to the above, the simultaneous editing of HSFA6a and HSFA6b lead to a reduced ROS accumulation, accompanied by increased expression of much abiotic stress and ABA-responsive genes, including involved in regulation of ROS level. In conclusion, these results suggest that HSFA6a and HSFA6b may offer abiotic stress tolerance by regulating the ROS homeostasis in plants.

Dolzblasz, Alicja; Banasiak, Alicja; Vereecke, Danny

doi: 10.1080/15592324.2020.1816320pmid: 32897774

Rhodococcus fascians is a gram-positive phytopathogen that infects a wide range of plant species. The actinomycete induces the formation of neoplastic growths, termed leafy galls, that consist of a gall body covered by small shoots of which the outgrowth is arrested due to an extreme form of apical dominance. In our previous work, we demonstrated that in the developing gall, auxin drives the transdifferentiation of parenchyma cells into vascular elements. In this work, with the use of transgenic Arabidopsis thaliana plants carrying molecular reporters for cell division (pCYCB1;1:GUS) and meristematic activity (pSTM:GUS), we analyzed the fate of cells within the leafy gall. Our results indicate that the size of the gall body is determined by ongoing mitotic cell divisions as illustrated by strong CYCB1;1 expression combined with the de novo formation of new meristematic areas triggered by STM expression. The shoot meristems that develop in the peripheral parts of the gall are originating from high ectopic STM expression. Altogether the presented data provide further insight into the cellular events that accompany the development of leafy galls in response to R. fascians infection.

Chen, Linxiao; Xia, Wei; Song, Jinxing; Wu, Mengqi; Xu, Zhizhen; Hu, Xiangyang; Zhang, Wenqing

doi: 10.1080/15592324.2020.1816322pmid: 32902365

Heat stress is a major growth-limiting factor for most crops over the world. Chitin elicitor receptor kinase 1 (CERK1) is a chitin/chitooligosaccharides receptor, and ERECTA (ER) plays a crucial role in plant resistance to heat stress. In the present study, a chitooligosaccharides-induced CERK1n-ERc fusion gene was designed and synthesized, in which the extracellular domain and transmembrane domain of CERK1 gene is connected with the response region of ER gene. We successfully constructed the CERK1n-ERc fusion gene by Overlap PCR and introduced it into Arabidopsis by Agrobacterium-medicated infection. Genetically modified (GM) plants had a greater germination rate and germination index, as well as a shorter mean germination time, indicating that they had a better thermotolerance compared with the wild-type (WT) lines under heat stress. Moreover, the GM lines showed a lower level of hydrogen peroxide (H2O2) and relative electrolyte leakage (REL), suggesting that they were in better state compared with the WT plants when exposed to high temperature. UPLC-MS/MS was employed to assess the phytohormone level, suggesting that the GM lines acquired a better thermotolerance via jasmonic acid (JA) signaling pathways. In general, we constructed a COS-induced fusion gene to enhance the thermotolerance of Arabidopsis during seed germination and postgermination growth.

Li, Chengjie; Han, Yingyan; Hao, Jinghong; Qin, Xiaoxiao; Liu, Chaojie; Fan, Shuangxi

doi: 10.1080/15592324.2020.1824697pmid: 32985921

In this research, the lettuce high-temperature-sensitive variety Beisan San 3 was used as a test material. The effects of exogenous spermidine (Spd) on membrane lipid peroxidation, the antioxidant system, the ascorbic acid-glutathione (AsA-GSH) system and the glyoxalase (Glo) system in lettuce seedlings under high-temperature stress were studied by spraying either 1 mM spermidine or ionized water as a control. The results showed that, under high-temperature stress, the growth of lettuce seedlings was weak, and the dry weight (DW) and fresh weight (FW) were reduced by 68.9% and 82%, respectively, compared with those of the normal-temperature controls. In addition, the degree of membrane lipid peroxidation increased, and the reactive oxygen species (ROS) level increased, both of which led to a significant increase in malondialdehyde (MDA) content and lipoxygenase (LOX) activity. Under high-temperature stress, the activity of superoxide dismutase (SOD) decreased, the activities of peroxidase (POD) and catalase (CAT) increased first but then decreased, and the activity of ascorbic acid peroxidase (APX) decreased first but then increased. Glutathione reductase (GR) activity, ascorbic acid (AsA) and glutathione (GSH) content showed an upward trend under high-temperature stress. The activities of glyoxalase (GloI and GloII) in the lettuce seedling leaves increased significantly under high-temperature stress. In contrast, the application of exogenous Spd alleviated the oxidative damage to the lettuce seedlings, which showed a decrease in MDA content and LOX activity and an increase in SOD, POD, CAT, APX, GR, GloI, and GloII activities. In addition, the antioxidant AsA and GSH contents also increased to varying degrees. It can be seen from the results that high temperature stress leads to an increase in the level of ROS and cause peroxidation in lettuce seedlings, and exogenous Spd can enhance the ability of lettuce seedlings to withstand high temperature by enhancing the antioxidant system, glyoxalase system and AsA-GSH cycle system.

Bai, Zhenqing; Zu, Huanhuan; Wang, Rui; Gao, Xinxin; Zou, Ting; Chen, Guoliang; Wu, Jiawen

doi: 10.1080/15592324.2020.1834749pmid: 33100139

The fruit of Chinese jujube (Ziziphus jujube) is widely consumed by human beings due to its high proteins, vitamins, and mineral nutrients. The harvest time of Chinese jujube fruit determines its quality, while ethylene plays a pivotal role in fruit ripening. Nevertheless, the relationship between ethylene biosynthesis/signal transduction and fruit ripening of Chinese jujube is still elusive. Here, the Chinese jujube fruit ripening with its fruit peel color change from cyan to dark red at seven different ripening stages (stage I–VII) and expression levels of genes related to ethylene synthesis and signal transduction were determined. Results showed that expression levels of ZjACO1-3, ZjETR2, ZjERF1, and ZjERF4 were increasingly upregulated, whereas the expression levels of ZjERS1, ZjETI, ZjERF2, and ZjERF3 were downregulated from green to red fruit ripening stages. Among them, ZjACO1-3 promoters contain ethylene response element. Taken together, Chinese jujube fruit ripening might be affected by the ethylene signaling which was mainly regulated by ZjACO, a gene involved in ethylene biosynthesis. This research supports theories and techniques for the storage, preservation and molecular breeding of Z. jujube.

Xi, Gangjun; Shi, Jun; Li, Jingbao; Han, Zhengmin

doi: 10.1080/15592324.2020.1816644pmid: 32897833

Orchid mycorrhizal fungi (OMF) are essential for orchids growth. Bletilla striata (Thunb.) Rchb.f.(Orchidaceae) has high ornamental and medicinal value. Beneficial OMF isolation is crucial to improve the survival rate of B. striata tissue culture and transplanting. In this study, we isolated and identified the beneficial OMF in B. striata from the roots of sterilized wild B. striata seedlings by culturing in four different mediums. The germination states of B. striata seeds inoculated with diverse OMF were classified and calculated. Fresh and dry weight increments of B. striata seedlings inoculated with diverse OMF were recorded after 90 d of culturing on 1/2 MS medium. ITS sequences of beneficial fungi were amplified by PCR and taxonomically identified using BLAST against the GenBank nucleotide database. Ten kinds of OMF strains were isolated from B. striata and named R1 to R10. R6 significantly promoted B. striata seeds germination (p < .01). R3 and R6 significantly promoted both the fresh and dry weight increments of B. striata seedlings (p < .05). The ITS sequence of R6 was most similar to the sequence of Serendipita. R3 was identified as Schizothecium fimbriatum by 100% ITS identity. R6 and R3 were beneficial OMF in B. striata.