 Your new post is loading...
Your new post is loading...
Authors: Qing Li, Qianqian Tian, Yue Zhang, Mengxue Niu, Xiaoqian Yu, Conglong Lian, Chao Liu, Hou-Ling Wang, Weilun Yin & Xinli Xia
Plant Cell, Tissue and Organ Culture (2022)
Abstract: "Abscisic acid (ABA), a key plant hormone that regulates plant growth development and stress response, is recognized and bound by ABA Receptor PYR/PYL/RCAR (referred to as PYLs). However, little is known about the PYL gene family in Populus euphratica. Here, we identified 12 PYLs in P. euphratica, termed PePYL1-12. The phylogenetic analysis divided 12 PePYLs into three subfamilies according to structural features of the amino acid sequence. The Subcellular localization analysis found that PePYL1, PePYL2, PePYL3, PePYL4, PePYL5, PePYL6, PePYL7, PePYL8, PePYL9 PePYL10, PePYL11 and PePYL12 were located in the cytoplasm and nucleus. The promoter analysis showed that various hormones- and stress-related cis-acting elements in the promoter of 12 PePYLs. Additionally, the expression analysis of 12 PePYLs were detected under ABA and drought treatments. And PePYL6 and PePYL9 were significantly induced by ABA and drought treatments. Thus, we generated transgenic Arabidopsis plants overexpressing PePYL6 and PePYL9 to study the performance of PePYLs under drought stress. Transgenic plants exhibited increased ABA sensitivity during seed germination and root growth, improved water use efficiency and enhanced tolerance to drought compared to wild type plants. Taken together, our studies provide useful information for further investigating the role of other PePYLs in response to abiotic stress in poplar.
Authors: Qian Liu, Guang-rui Dong, Yu-qing Ma, Shu-man Zhao, Xi Liu, Xing-kun Li, Yan-jie Li and Bing-kai Hou.
Frontiers in Plant Science (2021)
Abstract: "Drought is one of the most important environmental constraints affecting plant growth and development and ultimately leads to yield loss. Uridine diphosphate (UDP)-dependent glycosyltransferases (UGTs) are believed to play key roles in coping with environmental stresses. In rice, it is estimated that there are more than 200 UGT genes. However, most of them have not been identified as their physiological significance. In this study, we reported the characterization of a putative glycosyltransferase gene UGT85E1 in rice. UGT85E1 gene is significantly upregulated by drought stress and abscisic acid (ABA) treatment. The overexpression of UGT85E1 led to an enhanced tolerance in transgenic rice plants to drought stress, while the ugt85e1 mutants of rice showed a more sensitive phenotype to drought stress. Further studies indicated that UGT85E1 overexpression induced ABA accumulation, stomatal closure, enhanced reactive oxygen species (ROS) scavenging capacity, increased proline and sugar contents, and upregulated expression of stress-related genes under drought stress conditions. Moreover, when UGT85E1 was ectopically overexpressed in Arabidopsis, the transgenic plants showed increased tolerance to drought as well as in rice. Our findings suggest that UGT85E1 plays an important role in mediating plant response to drought and oxidative stresses. This work may provide a promising candidate gene for cultivating drought-tolerant crops both in dicots and monocots."
Authors: Chao Han, Wenbo Hua, Jinge Li, Yan Qiao, Lianmei Yao, Wei Hao, Ruizhi Li, Min Fan, Geert De Jaeger, Wenqiang Yang and Ming-Yi Bai.
The Plant Cell (2022)
Abstract: "Starch is the main energy storage carbohydrate in plants and serves as an essential carbon storage molecule for plant metabolism and growth under changing environmental conditions. The TARGET of RAPAMYCIN (TOR) kinase is an evolutionarily conserved master regulator that integrates energy, nutrient, hormone, and stress signaling to regulate growth in all eukaryotes. Here, we demonstrate that TOR promotes guard cell starch degradation and induces stomatal opening in Arabidopsis thaliana. Starvation, caused by plants growing under short photoperiod or low light photon irradiance, as well as inactivation of TOR, impaired guard cell starch degradation and stomatal opening. Sugar and TOR induce the accumulation of β-AMYLASE1 (BAM1), which is responsible for starch degradation in guard cells. The plant steroid hormone brassinosteroid (BR) and transcription factor BZR1 play crucial roles in sugar-promoted expression of BAM1. Furthermore, sugar supply induced BAM1 accumulation, but TOR inactivation led to BAM1 degradation, and the effects of TOR inactivation on BAM1 degradation were abolished by the inhibition of autophagy and proteasome pathways or by phospho-mimicking mutation of BAM1 at serine-31. Such regulation of BAM1 activity by sugar–TOR signaling allows carbon availability to regulate guard cell starch metabolism and stomatal movement, ensuring optimal photosynthesis efficiency of plants."
Authors: Takashi Kuromori, Miki Fujita, Fuminori Takahashi, Kazuko Yamaguchi-Shinozaki and Kazuo Shinozaki.
The Plant Journal (2022)
Abstract: "Plant response to drought stress includes systems for intracellular regulation of gene expression and signaling, as well as inter-tissue and inter-organ signaling, which helps entire plants acquire stress resistance. Plants sense water-deficit conditions both via the stomata of leaves and roots, and transfer water-deficit signals from roots to shoots via inter-organ signaling. ABA is an important phytohormone involved in drought stress response and adaptation, and is synthesized mainly in vascular tissues and guard cells of leaves. In leaves, stress-induced ABA is distributed to various tissues by transporters, which activates stomatal closure and expression of stress-related genes to acquire drought stress resistance. Moreover, stepwise stress response at the whole-plant level is important for proper understanding of the physiological response to drought conditions. Drought stress is sensed by multiple types of sensors as molecular patterns of abiotic stress signals, which are transmitted via separate parallel signaling networks to induce downstream responses, including stomatal closure and synthesis of stress-related proteins and metabolites. Peptide molecules play important roles in the inter-organ signaling of dehydration from roots to shoots, as well as signaling of osmotic changes and reactive oxygen species/Ca2+. In this review, we have summarized recent advances in research on complex plant drought stress responses, focusing on inter-tissue signaling in leaves and inter-organ signaling from roots to shoots. We have discussed the mechanisms via which drought stress adaptations and resistance are acquired at the whole-plant level, and have proposed the importance of quantitative phenotyping for measuring plant growth under drought conditions.
Authors: Jieyang Jin, Mingyue Zhao, Ting Gao, Tingting Jing, Na Zhang, Jingming Wang, Xianchen Zhang, Jin Huang, Wilfried Schwab and Chuankui Song.
Horticulture Research (2021)
Abstract: "Plants have developed sophisticated mechanisms to survive in dynamic environments. Plants can communicate via volatile organic compounds (VOCs) to warn neighboring plants of threats. In most cases, VOCs act as positive regulators of plant defense. However, the communication and role of volatiles in response to drought stress are poorly understood. Here, we showed that tea plants release numerous VOCs. Among them, methyl salicylate (MeSA), benzyl alcohol, and phenethyl alcohol markedly increased under drought stress. Interestingly, further experiments revealed that drought-induced MeSA lowered the abscisic acid (ABA) content in neighboring plants by reducing 9-cis-epoxycarotenoid dioxygenase (NCED) gene expression, resulting in inhibition of stomatal closure and ultimately decreasing early drought tolerance in neighboring plants. Exogenous application of ABA reduced the wilting of tea plants caused by MeSA exposure. Exposure of Nicotiana benthamiana to MeSA also led to severe wilting, indicating that the ability of drought-induced MeSA to reduce early drought tolerance in neighboring plants may be conserved in other plant species. Taken together, these results provide evidence that drought-induced volatiles can reduce early drought tolerance in neighboring plants and lay a novel theoretical foundation for optimizing plant density and spacing."
Authors: Xiaoming Yin, Ya-Li Bai, Tiantian Ye, Min Yu, Yan Wu and Yu-Qi Feng.
Journal of Experimental Botany (2022)
Abstract: "Phaseic acid (PA), a main catabolite of abscisic acid (ABA), is structurally related to ABA and possesses ABA-like hormonal activity. However, the comprehensive metabolism pathway and roles of PA is not well understood. Here, we identified the previously named CRL1 (Cinnamoyl coA:NADP oxidoreductase like 1) as a PA reductase that catalyzes PA to dihydrophaseic acid (DPA) via a homologous alignment and expression pattern analysis strategy in Arabidopsis. The function of CRL1 and the potential role of PA were studied in the genetically transgenic material of CRL1. Overexpression of CRL1 (OE) resulted in decreased ABA sensitivity in seed germination and attenuated drought tolerance. In contrast, increased ABA sensitivity and elevated drought tolerance was observed in down-regulated and loss-of-function crl1 mutants. The Tyr162 residues in the conserved motif of CRL1 is key to the PA catalytic activity. Accelerated seed germination and earlier flowering phenotype was also observed in OE lines, while retarded seed germination and delayed flowering time in crl1 mutants which accumulated more PA while less DPA than the wildtype (WT). This study demonstrates that PA plays diverse functions in plant including drought tolerance, seed germination and flowering in an ABA-like manner, which may expand the plant adaptive plasticity."
Authors: Sang Im Oh, Jongyun Kim and Ae Kyung Lee.
Horticultural Science and Technology (2021)
Abstract: "This study compared the shelf life and quality of potted hydrangea (‘Speedy Red’) treated with different abscisic acid (ABA) spray concentrations and investigated the associated physiological changes. Plants were treated with 0 (control), 1,000, 2,000, or 2,500 mg·L-1 ABA, which was applied by spraying. Treatment with 2,000 and 2,500 mg·L-1 ABA extended the hydrangea shelf life by 2 days compared to the control, and the 2,000 mg·L-1 treatment attenuated change in sepal color and wilting compared to other treatments, suggesting quality control in potted plants. Additionally, the 2,000 mg·L-1 ABA spray treatment increased stomatal closure up to day 5 post-treatment, corresponding to the end of the shelf life for treated plants, indicating that ABA spray decreased transpiration-induced water loss. The 2,000 mg·L-1 ABA spray treatment resulted in the highest maximum quantum yield of PSII among the treatments, and the normalized difference vegetation index and the simple ratio index values were also higher than those obtained with other treatments. Thus, 2,000 mg·L-1 ABA spray treatment mitigated water stress by inducing stomatal closure in potted hydrangea (‘Speedy Red’). Overall, the ABA spray treatment controlled stomatal closure and effectively inhibited transpiration, which minimized water loss and preserved plant moisture levels, thereby extending shelf life and quality. Our study also assessed the potential use of nondestructive measurements (e.g., chlorophyll fluorescence and vegetation indices) to monitor the quality of potted hydrangea, which may facilitate the evaluation of potted flower quality on site. ABA spray treatment at 2,000 mg·L-1 effectively extends the shelf life and improves the quality of potted hydrangea (‘Speedy Red’). These results are useful for the postharvest management of potted hydrangeas."
Authors: Chaemyeong Lim, Kiyoon Kang, Yejin Shim, Soo-Cheul Yoo and Nam-Chon Paek.
Plant Physiology (2022)
One-sentence summary: Under water-deficient conditions, mutation of rice OsWRKY5, which negatively regulates drought stress-tolerant genes under normal growth conditions, increases abscisic acid-induced drought tolerance.
Abstract: "During crop cultivation, water-deficit conditions retard growth, thus reducing crop productivity. Therefore, uncovering the mechanisms behind drought tolerance is a critical task for crop improvement. Here, we show that the rice (Oryza sativa) WRKY transcription factor OsWRKY5 negatively regulates drought tolerance. We determined that OsWRKY5 was mainly expressed in developing leaves at the seedling and heading stages, and that its expression was reduced by drought stress and by treatment with NaCl, mannitol, and abscisic acid (ABA). Notably, the genome-edited loss-of-function alleles oswrky5-2 and oswrky5-3 conferred enhanced drought tolerance, measured as plant growth under water-deficit conditions. Conversely, the overexpression of OsWRKY5 in the activation-tagged line oswrky5-D resulted in higher susceptibility under the same conditions. Loss of OsWRKY5 activity increased sensitivity to ABA, thus promoting ABA-dependent stomatal closure. Transcriptome deep sequencing and RT-qPCR analyses demonstrated that the expression of abiotic stress-related genes including rice MYB2 (OsMYB2) was upregulated in oswrky5 knockout mutants and downregulated in oswrky5-D mutants. Moreover, dual-luciferase, yeast one-hybrid, and chromatin immunoprecipitation assays showed that OsWRKY5 directly binds to the W-box sequences in the promoter region of OsMYB2 and represses OsMYB2 expression, thus downregulating genes downstream of OsMYB2 in the ABA signaling pathways. Our results demonstrate that OsWRKY5 functions as a negative regulator of ABA-induced drought stress tolerance, strongly suggesting that inactivation of OsWRKY5 or manipulation of key OsWRKY5 targets could be useful to improve drought tolerance in rice cultivars."
Authors: Yuqin Zhang, Himabindu Vasuki Kilambi, Jie Liu, Hamutal Bar, Shani Lazary, Aiman Egbaria, Dagmar Ripper, Laurence Charrier, Zeinu Mussa Belew, Nikolai Wulff, Suresh Damodaran, Hussam Hassan Nour-Eldin, Asaph Aharoni, Laura Ragni, Lucia Strader, Nir Sade, Roy Weinstain, Markus Geisler and Eilon Shani.
Science Advances (2021)
One-sentence summary: ABCG17 and ABCG18 ABA importers redundantly regulate ABA homeostasis and long-distance translocation.
Abstract: "The effects of abscisic acid (ABA) on plant growth, development, and response to the environment depend on local ABA concentrations. Here, we show that in Arabidopsis, ABA homeostasis is regulated by two previously unknown ABA transporters. Adenosine triphosphate–binding cassette subfamily G member 17 (ABCG17) and ABCG18 are localized to the plasma membranes of leaf mesophyll and cortex cells to redundantly promote ABA import, leading to conjugated inactive ABA sinks, thus restricting stomatal closure. ABCG17 and ABCG18 double knockdown revealed that the transporters encoded by these genes not only limit stomatal aperture size, conductance, and transpiration while increasing water use efficiency but also control ABA translocation from the shoot to the root to regulate lateral root emergence. Under abiotic stress conditions, ABCG17 and ABCG18 are transcriptionally repressed, promoting active ABA movement and response. The transport mechanism mediated by ABCG17 and ABCG18 allows plants to maintain ABA homeostasis under normal growth conditions."
Authors: Preeti Nagar, Namisha Sharma, Muskan Jain, Gauri Sharma, Manoj Prasad and Ananda Mustafiz.
Physiologia Plantarum (2022)
Abstract: "Abscisic acid (ABA) is a major phytohormone that acts as stimuli and plays an important role in plant growth, development and environmental stress responses. Membrane-localized receptor-like kinases (RLKs) help to detect extracellular stimuli and activate downstream signaling responses to modulate a variety of biological processes. Phytosulfokine receptor (PSKR), a Leu-rich repeat (LRR)-RLK, has been characterized for its role in growth, development and biotic stress. Here, we observed that OsPSKR15, a rice PSKR, was upregulated by ABA in Oryza sativa. We demonstrated OsPSKR15 is a positive regulator in plant response to ABA. Ectopic expression of OsPSKR15 in Arabidopsis thaliana increased the sensitivity to ABA during germination, growth and stomatal closure. Consistently, the expression of ABA-inducible genes was significantly upregulated in these plants. OsPSKR15 also regulated reactive oxygen species (ROS)-mediated ABA signaling in guard cells, thereby governing stomatal closure. Furthermore, the constitutive expression of OsPSKR15 enhanced drought tolerance by reducing the transpirational water loss in Arabidopsis. We also reported that OsPSKR15 directly interacts with AtPYL9 and its orthologue OsPYL11 of rice through its kinase domain in the plasma membrane and nucleus. Altogether, these results reveal an important role of OsPSKR15 in plant response towards abiotic stress in an ABA-dependent manner."
Authors: Hagai Shohat, Hadar Cheriker, Himabindu Vasuki Kilambi, Natanella Illouz Eliaz, Shula Blum, Ziva Amsellem, Danuše Tarkowská, Asaph Aharoni, Yuval Eshed and David Weiss.
New Phytologist (2021)
Abstract: "Plants reduce transpiration to avoid dehydration during drought episodes by stomatal closure and inhibition of canopy growth. Previous studies suggest that low gibberellin (GA) activity promotes these 'drought avoidance' responses. Using genome editing, molecular, physiological and hormone analyses, we examined if drought regulates GA metabolism in tomato (Solanum lycopersicum) guard cells and leaves, and studied how this affects water loss. Water deficiency inhibited the expression of the GA biosynthesis genes GA20 oxidase1 (GA20ox1) and GA20ox2 and induced the GA-deactivating gene GA2ox7 in guard cells and leaf tissue, resulting in reduced levels of bioactive GAs. These effects were mediated by ABA-dependent and independent pathways, and by the transcription factor TINY1. The loss of GA2ox7 attenuated stomatal response to water deficiency and during soil dehydration, ga2ox7 plants closed their stomata later, and wilted faster than wild type (WT) M82 cv. Mutations in GA20ox1 and GA20ox2, had no effect on stomatal closure, but reduced water loss due to the mutants' smaller canopy area. The results suggest that drought-induced GA deactivation in guard cells, contributes to stomatal closure at the early stages of soil dehydration, whereas inhibition of GA synthesis in leaves, suppresses canopy growth and restrict transpiration area.
Authors: Shanzhi Wang, Shuai Li, Jiyang Wang, Qian Li, Xiu-Fang Xin, Shuang Zhou, Yanping Wang, Dayong Li, Jiaqing Xu, Zhao-Qing Luo, Sheng Yang He and Wenxian Sun
Nature Communications (2021)
Editor's view: XopC2 effectors are present in many plant bacterial pathogens. Here the authors show that XopC2 has kinase activity and enhances disease susceptibility by phosphorylating the OSK1 protein, which increases its interaction with the jasmonate receptor COI1b to promote JA signaling and stomatal opening.
Abstract: "The Xanthomonas outer protein C2 (XopC2) family of bacterial effectors is widely found in plant pathogens and Legionella species. However, the biochemical activity and host targets of these effectors remain enigmatic. Here we show that ectopic expression of XopC2 promotes jasmonate signaling and stomatal opening in transgenic rice plants, which are more susceptible to Xanthomonas oryzae pv. oryzicola infection. Guided by these phenotypes, we discover that XopC2 represents a family of atypical kinases that specifically phosphorylate OSK1, a universal adaptor protein of the Skp1-Cullin-F-box ubiquitin ligase complexes. Intriguingly, OSK1 phosphorylation at Ser53 by XopC2 exclusively increases the binding affinity of OSK1 to the jasmonate receptor OsCOI1b, and specifically enhances the ubiquitination and degradation of JAZ transcription repressors and plant disease susceptibility through inhibiting stomatal immunity. These results define XopC2 as a prototypic member of a family of pathogenic effector kinases and highlight a smart molecular mechanism to activate jasmonate signaling. "
Authors: Sisi Chen, Xiaofeng Wang, Honglei Jia, Fali Li, Ying Ma, Johannes Liesche, Mingzhi Liao, Xueting Ding, Cuixia Liu, Ying Chen, Na Li and Jisheng Li.
Molecular Plant (2021)
Abstract: "Post-translational modifications (PTMs), including phosphorylation and persulfidation, regulate the activity of SNF1-RELATED PROTEIN KINASE2.6 (SnRK2.6). Here, we report how persulfidations and phosphorylations of SnRK2.6 influence each other. The persulfidation of cysteine C131/C137 alters SnRK2.6 structure and brings the serine S175 residue closer to the aspartic acid D140 that acts as ATP-γ-phosphate proton acceptor, thereby improving the transfer efficiency of phosphate groups to S175 to enhance the phosphorylation level of S175. Interestingly, we predicted that S267 and C137 were predicted to lie in close proximity on the protein surface and found that the phosphorylation status of S267 positively regulates the persulfidation level at C137. Analyses of the responses of dephosphorylated and depersulfidated mutants to abscisic acid and the H2S-donor NaHS during stomatal closure, water loss, gas exchange, Ca2+ influx, and drought stress revealed that S175/S267-associated phosphorylation and C131/137-associated persulfidation are essential for SnRK2.6 function in vivo. In light of these findings, we propose a mechanistic model in which certain phosphorylations facilitate persulfidation, thereby changing the structure of SnRK2.6 and increasing its activity."
|
Authors: Yue Shi, Xiangning Liu, Shuangshuang Zhao and Yan Guo.
New Phytologist (2022)
Abstract: "Limiting water loss by reducing transpiration helps plants survive when water is limited. Under drought stress, abscisic acid (ABA)-mediated gene expression and anion channel activation regulate stomatal closure and stress responses. ABA-induced actin reorganization also affects stomatal closure, but the underlying molecular mechanism remains unclear. In this study, we discovered that under non-stress conditions, the clade A PP2C phosphatases, such as ABI1 and ABI2, interacts with CKL2 and inhibits its kinase activity in Arabidopsis. Under drought stress, CKL2 kinase activity was released through the formation of a complex containing ABA, PP2C, and a PYR1/PYL/RCAR family (PYL) receptor. The activated CKL2 regulating actin reorganization is another important process to maintain stomatal closure besides ABA-activated SnRK2 signaling. Moreover, CKL2 phosphorylated PYR1-LIKE 1, ABI1 and ABI2 at amino acid residues conserved among PYLs and PP2Cs, and stabilized ABI1 protein. Our results reveal that ABA signaling regulates actin reorganization to maintain stomatal closure during drought stress and the feedback regulation of PYL1, ABI1 and ABI2 by the CKL2 kinase might fine-tune ABA signaling and affect plant ABA responses."
Authors: Abhilasha Abhilasha and Swarup Roy Choudhury.
Plants (2021)
Abstract: "Drought is the most prevalent unfavorable condition that impairs plant growth and development by altering morphological, physiological, and biochemical functions, thereby impeding plant biomass production. To survive the adverse effects, water limiting condition triggers a sophisticated adjustment mechanism orchestrated mainly by hormones that directly protect plants via the stimulation of several signaling cascades. Predominantly, water deficit signals cause the increase in the level of endogenous ABA, which elicits signaling pathways involving transcription factors that enhance resistance mechanisms to combat drought-stimulated damage in plants. These responses mainly include stomatal closure, seed dormancy, cuticular wax deposition, leaf senescence, and alteration of the shoot and root growth. Unraveling how plants adjust to drought could provide valuable information, and a comprehensive understanding of the resistance mechanisms will help researchers design ways to improve crop performance under water limiting conditions. This review deals with the past and recent updates of ABA-mediated molecular mechanisms that plants can implement to cope with the challenges of drought stress."
Authors: Xiaobin Ou, Tianqi Li, Yi Zhao, Yuankai Chang, Lihong Wu, Guoqingzi Chen, Brad Day and Kun Jiang.
Journal of Plant Physiology (2022)
Highlights: • Stomatal ABA and PAMP signaling pathways converge at calcium-dependent protein kinases (CDPKs). • The CDPKs reinforce the rapid, local SA responses in guard cells. • ABA mediates stomatal responses to biotic and abiotic stresses via two partially overlapping signaling modules.
Abstract: "Stomatal immunity is mediated by ABA, an osmotic stress-responsive phytohormone that closes stomata via calcium-dependent and -independent signaling pathways. However, the functional involvement of ABA signal transducers in stomatal immunity remains poorly understood. Here, we demonstrate that stomatal immunity was compromised in mutants of the ABA signaling core. We also found that it is a subset of calcium-dependent protein kinases (CPK4/5/6), but not the calcium-independent kinase OST1, that relay the stomatal immune signaling. Surface-inoculated bacteria caused an endogenous ABA-dependent induction of local SA responses, whilst expression of the ABA biosynthetic genes and the ABA levels were not affected in leaf epidermis. Furthermore, flg22-elicited ROS burst was attenuated by mutations in CPK4 and CPK5, and pathogen-induced SA production in leaf epidermis was compromised in cpk4, cpk5, and cpk6 mutants. Our results suggest that CPKs function in stomatal immunity through fine-tuning apoplastic ROS levels as well as reinforcing the localized SA signal in guard cells. It is also envisioned that ABA mediates stomatal responses to biotic and abiotic stresses via two distinct but partially overlapping signaling modules."
Authors: Yen-Hsin Chiu, Yu-Ling Hung, Hsin-Ping Wang, Wei-Lun Wei, Qian-Wen Shang, Thanh Ha Pham, Chien-Kang Huang, Zhao-Jun Pan and Shih-Shun Lin.
Viruses (2021)
Abstract: "The P1/HC-Pro viral suppressor of potyvirus suppresses posttranscriptional gene silencing (PTGS). The fusion protein of P1/HC-Pro can be cleaved into P1 and HC-Pro through the P1 self-cleavage activity, and P1 is necessary and sufficient to enhance PTGS suppression of HC-Pro. To address the modulation of gene regulatory relationships induced by turnip mosaic virus (TuMV) P1/HC-Pro (P1/HC-ProTu), a comparative transcriptome analysis of three types of transgenic plants (P1Tu, HC-ProTu, and P1/HC-ProTu) were conducted using both high-throughput (HTP) and low-throughput (LTP) RNA-Seq strategies. The results showed that P1/HC-ProTu disturbed the endogenous abscisic acid (ABA) accumulation and genes in the signaling pathway. Additionally, the integrated responses of stress-related genes, in particular to drought stress, cold stress, senescence, and stomatal dynamics, altered the expressions by the ABA/calcium signaling. Crosstalk among the ABA, jasmonic acid, and salicylic acid pathways might simultaneously modulate the stress responses triggered by P1/HC-ProTu. Furthermore, the LTP network analysis revealed crucial genes in common with those identified by the HTP network in this study, demonstrating the effectiveness of the miniaturization of the HTP profile. Overall, our findings indicate that P1/HC-ProTu-mediated suppression in RNA silencing altered the ABA/calcium signaling and a wide range of stress responses."
Authors: Dalong Zhang, Qingjie Du, Po Sun, Jie Lou, Xiaotian Li, Qingming Li and Min Wei.
Frontiers in Plant Science (2021)
Abstract: "The atmospheric vapour pressure deficit (VPD) has been demonstrated to be a significant environmental factor inducing plant water stress and affecting plant photosynthetic productivity. Despite this, the rate-limiting step for photosynthesis under varying VPD is still unclear. In the present study, tomato plants were cultivated under two contrasting VPD levels: high VPD (3–5 kPa) and low VPD (0.5–1.5 kPa). The effect of long-term acclimation on the short-term rapid VPD response was examined across VPD ranging from 0.5 to 4.5 kPa. Quantitative photosynthetic limitation analysis across the VPD range was performed by combining gas exchange and chlorophyll fluorescence. The potential role of abscisic acid (ABA) in mediating photosynthetic carbon dioxide (CO2) uptake across a series of VPD was evaluated by physiological and transcriptomic analyses. The rate-limiting step for photosynthetic CO2 utilisation varied with VPD elevation in tomato plants. Under low VPD conditions, stomatal and mesophyll conductance was sufficiently high for CO2 transport. With VPD elevation, plant water stress was gradually pronounced and triggered rapid ABA biosynthesis. The contribution of stomatal and mesophyll limitation to photosynthesis gradually increased with an increase in the VPD. Consequently, the low CO2 availability inside chloroplasts substantially constrained photosynthesis under high VPD conditions. The foliar ABA content was negatively correlated with stomatal and mesophyll conductance for CO2 diffusion. Transcriptomic and physiological analyses revealed that ABA was potentially involved in mediating water transport and photosynthetic CO2 uptake in response to VPD variation. The present study provided new insights into the underlying mechanism of photosynthetic depression under high VPD stress.
Authors: Menghao Zhu, Yonggang He, Mingqiang Zhu, Ayaz Ahmad, Shuang Xu, Zijun He, Shan Jiang, Jinqiu Huang, Zhihui Li, Shaojia Liu, Xin Hou and Zhihong Zhang.
Plant Cell Reports (2022)
Key message: ipa1 enhances rice drought tolerance mainly through activating the ABA pathway. It endows rice seedlings with a more developed root system, smaller leaf stomata aperture, and enhanced carbon metabolism.
Abstract: "Drought is a major abiotic stress to crop production. IPA1 (IDEAL PLANT ARCHITECTURE 1)/OsSPL14 encodes a transcription factor and has been reported to function in both rice ideal plant architecture and biotic resistance. Here, with a pair of IPA1 and ipa1-NILs (Near Iso-genic Lines), we found that ipa1 could significantly improve rice drought tolerance at seedling stage. The ipa1 plants had a better-developed root system and smaller leaf stomatal aperture. Analysis of carbon–nitrogen metabolism-associated enzyme activity, gene expression, and metabolic profile indicated that ipa1 could tip the carbon–nitrogen metabolism balance towards an increased carbon metabolism pattern. In both the control and PEG-treated conditions, ABA content in the ipa1 seedlings was significantly higher than that in the IPA1 seedlings. Expression of the ABA biosynthesis genes was detected to be up-regulated, whereas the expression of ABA catabolism genes was down-regulated in the ipa1 seedlings. In addition, based on yeast one-hybrid assay and dual-luciferase assay, IPA1 was found to directly activate the promoter activity of OsHOX12, a transcription factor promoting ABA biosynthesis, and OsNAC52, a positive regulator of the ABA pathway. The expression of OsHOX12 and OsNAC52 was significantly up-regulated in the ipa1 plants. Combined with the previous studies, our results suggested that ipa1 could improve rice seedling drought tolerance mainly through activating the ABA pathway and that regulation of the ipa1-mediated ABA pathway will be an important strategy for improving drought resistance of rice."
Authors: Sang-Uk Lee, Bong-Gyu Mun, Eun-Kyung Bae, Jae-Young Kim, Hyun-Ho Kim, Muhammad Shahid, Young-Im Choi, Adil Hussain and Byung-Wook Yun.
Frontiers in Plant Science (2021)
Abstract: "Populus trichocarpa has been studied as a model poplar species through biomolecular approaches and was the first tree species to be genome sequenced. In this study, we employed a high throughput RNA-sequencing (RNA-seq) mediated leaf transcriptome analysis to investigate the response of four different Populus davidiana cultivars to drought stress. Following the RNA-seq, we compared the transcriptome profiles and identified two differentially expressed genes (DEGs) with contrasting expression patterns in the drought-sensitive and tolerant groups, i.e., upregulated in the drought-tolerant P. davidiana groups but downregulated in the sensitive group. Both these genes encode a 9-cis-epoxycarotenoid dioxygenase (NCED), a key enzyme required for abscisic acid (ABA) biosynthesis. The high-performance liquid chromatography (HPLC) measurements showed a significantly higher ABA accumulation in the cultivars of the drought-tolerant group following dehydration. The Arabidopsis nced3 loss-of-function mutants showed a significantly higher sensitivity to drought stress, ~90% of these plants died after 9 days of drought stress treatment. The real-time PCR analysis of several key genes indicated a strict regulation of drought stress at the transcriptional level in the P. davidiana drought-tolerant cultivars. The transgenic P. davidiana NCED3 overexpressing (OE) plants were significantly more tolerant to drought stress as compared with the NCED knock-down RNA interference (RNAi) lines. Further, the NCED OE plants accumulated a significantly higher quantity of ABA and exhibited strict regulation of drought stress at the transcriptional level. Furthermore, we identified several key differences in the amino acid sequence, predicted structure, and co-factor/ligand binding activity of NCED3 between drought-tolerant and susceptible P. davidiana cultivars. Here, we presented the first evidence of the significant role of NCED genes in regulating ABA-dependent drought stress responses in the forest tree P. davidiana and uncovered the molecular basis of NCED3 evolution associated with increased drought tolerance."
Authors: Daisuke Takagi, Keiki Ishiyama, Mao Suganami, Tomokazu Ushijima, Takeshi Fujii, Youshi Tazoe, Michio Kawasaki, Ko Noguchi and Amane Makino.
Scientific Reports (2021)
Abstract: "Despite the essentiality of Mn in terrestrial plants, its excessive accumulation in plant tissues can cause growth defects, known as Mn toxicity. Mn toxicity can be classified into apoplastic and symplastic types depending on its onset. Symplastic Mn toxicity is hypothesised to be more critical for growth defects. However, details of the relationship between growth defects and symplastic Mn toxicity remain elusive. In this study, we aimed to elucidate the molecular mechanisms underlying symplastic Mn toxicity in rice plants. We found that under excess Mn conditions, CO2 assimilation was inhibited by stomatal closure, and both carbon anabolic and catabolic activities were decreased. In addition to stomatal dysfunction, stomatal and leaf anatomical development were also altered by excess Mn accumulation. Furthermore, indole acetic acid (IAA) concentration was decreased, and auxin-responsive gene expression analyses showed IAA-deficient symptoms in leaves due to excess Mn accumulation. These results suggest that excessive Mn accumulation causes IAA deficiency, and low IAA concentrations suppress plant growth by suppressing stomatal opening and leaf anatomical development for efficient CO2 assimilation in leaves."
Authors: Yun Chen, Jing-Bo Zhang, Ning Wei, Zhi-Hao Liu, Yang Li, Yong Zheng and Xue-Bao Li.
Plant Molecular Biology (2021)
Key message: GhDRP1 acts as a negatively regulator to participate in response to drought stress possibly by modulating ABA signaling pathway and flavonoid biosynthesis pathway which affects stomata movement and thus water loss, ROS scavenging enzymes, and proline accumulation in cotton.
Abstract: "Type-2C protein phosphatases (PP2C) may play important roles in plant stress signal transduction. Here, we show the evidence that a cotton PP2C protein GhDRP1 participates in plant response to drought stress. GhDRP1 gene encodes an active type-2C protein phosphatase (PP2C) and its expression is significantly induced in cotton by drought stress. Compared with wild type, the GhDRP1 overexpression (OE) transgenic cotton and Arabidopsis displayed reduced drought tolerance, whereas GhDRP1-silenced (RNAi) cotton showed enhanced drought tolerance. Under drought stress, malondialdehyde content was lower, whereas superoxide dismutase and peroxidase activities, proline content, stomata closure and relative water content were higher in GhDRP1 RNAi plants compared with those in wild type. In contrast, GhDRP1 OE plants showed the opposite phenotype under the same conditions. Expression levels of some stress-related and flavonoid biosynthesis-related genes were altered in GhDRP1 transgenic plants under drought stress. Additionally, GhDRP1 protein could interact with other proteins such as PYLs, SNF1-related protein kinase and GLK1-like protein. Collectively, these data suggest that GhDRP1 participates in plant response to drought stress possibly by modulating ABA signaling pathway and flavonoid biosynthesis pathway which affects stomata movement and thus water loss, ROS scavenging enzymes, and proline accumulation in cotton."
Authors: Pedro Castro-Valdecantos, Jaime Puértolas, Alfonso Albacete and Ian C. Dodd.
Environmental and Experimental Botany (2021)
Highlights: • Girdling modified the co-ordination of root and leaf phytohormones. • JA and ABA may act as antitranspirants closing the stomata in the first 26 hours. • Leaf ABA concentration better explained variation in stomatal conductance than other hormones
Abstract: "To investigate the importance of shoot-to-root communication in modulating tissue phytohormone balance as the soil dries, root and leaf hormonal profiles were determined in soybean plants (Glycine max L. Merr. cv. Siverka) exposed to factorial girdling (achieved surgically on Day 0 by excising the phloem with a sharp razor blade thereby disrupting basipetal hormone transport) and soil drying treatments. Plants were randomized into 2 groups: girdled and intact plants, and each girdled group was further separated into two groups: well-watered and soil drying. Thus the experiment was a two (± girdling) x two (± soil drying) factorial experiment. Within 26 h while the soil was still moist, girdling increased root ACC (by 11-fold) and decreased root ABA concentrations (by 28%), decreased foliar iP, tZ and GA3 concentrations (by up to 90%), and increased foliar ABA and JA concentrations (by 1.6- and 4.9-fold respectively) compared to intact plants, but only leaf ABA concentration correlated with partial stomatal closure. Two days of soil drying increased root ABA and JA concentrations in intact plants, and both hormones significantly decreased in roots of girdled plants compared to intact plants. Soil drying increased foliar iP, ABA, JA and SA concentrations by 1.3-, 2.5-, 1.3- and 1.4-fold respectively compared to well-watered intact plants by the end of the experiment, but girdling prevented this foliar iP, ABA, JA accumulation compared to droughted intact plants. Thus, girdling affects the co-ordination of root and leaf phytohormone concentrations such as JA and ABA, which may transiently modulate stomatal closure. However, leaf ABA concentration varied consistently with root ABA concentration across all treatments, and explained more of the variation in stomatal conductance than any other hormone or leaf water potential."
Authors: Ting Wang, Yu-qing Ma, Xiu-xiu Huang, Tian-jiao Mu, Yan-jie Li, Xing-kun Li, Xi Liu and Bing-kai Hou.
Environmental and Experimental Botany (2021)
Highlights: • Rice glycosyltransferase gene UGT3 is isolated and characterized. • Overexpression of UGT3 enhanced drought and salt stress tolerance. • UGT3 transgenic plants increased endogenous ABA level. • UGT3 can enhance ROS scavenging capacity.
Abstract: "Abscisic acid (ABA) is an important plant hormone that plays a crucial role in response to abiotic stresses. It is well-known that the level of ABA will be dynamically regulated under stress conditions, however, the regulatory mechanism of ABA homeostasis remains largely unknown. In this study, we isolated and characterized a putative UDP-glycosyltransferase (UGT3) in rice, which is proven to be stress-induced and involved in ABA dynamic change. Our data demonstrated that overexpression of the glycosyltransferase gene UGT3 enhanced drought and salt stress tolerance of the transgenic rice. However, ugt3 mutant exhibited sensitive phenotypes under stresses. The ectopic expression of UGT3 in Arabidopsis also enhanced the plant tolerance to drought and salt stresses. Overexpression of UGT3 in rice increased endogenous ABA level and showed hypersensitive phenotype to exogenous ABA treatment at both germination and post-germination stages. Further studies demonstrated that UGT3 elevated activities of the antioxidant enzymes and reduced the production of reactive oxygen species to control the oxidative burst under stress conditions. Taken together, this work reveals that glycosyltransferase UGT3 can cope with the environmental challenges through a possible interactive network of ABA, ROS and antioxidants under abiotic stresses."
Authors: Jian Chen, Heng Zhou and Yanjie Xie.
Trends in Plant Science (2021)
Excerpts: "Hydrogen sulfide (H2S) signaling regulates plant responses to adverse conditions via persulfidation of proteins. Recently, Chen et al. proposed that mechanistic interplay between H2S-linked persulfidation- and phosphorylation-based regulation of SNF1-RELATED PROTEIN KINASE 2.6 (SnRK2.6) modulates these pathways, providing a missing link to explain how plants coordinate abscisic acid (ABA) and H2S signaling in drought responses."
"The study by Chen et al. corroborates the role of persulfidation and phosphorylation within the context of modulation of SnRK2.6 structure and function [8]. Their recent publication not only provides compelling evidence demonstrating (for the first time) an interaction between H2S and ABA signaling in guard cells, but also establishes a new paradigm for persulfidation-mediated regulation of other key proteins involved in ABA signaling [7,8]. However, these findings raised the question of whether the H2S/persulfidation signal also works outside of guard cells."
|
