Arabidopsis MADS-box factor AGL16 negatively regulates drought resistance via stomatal density and stomatal movement

Abstract Drought is one of the most important environmental factors limiting plant growth and productivity. The molecular mechanisms underlying plant drought resistance are complex and not yet fully understood. Here, we show that the Arabidopsis MADS-box transcription factor AGL16 acts as a negative regulator in drought resistance by regulating stomatal density and movement. Loss-of-AGL16 mutants were more resistant to drought stress and had higher relative water content, which was attributed to lower leaf stomatal density and more sensitive stomatal closure due to higher leaf ABA levels compared with the wild type. AGL16-overexpressing lines displayed the opposite phenotypes. AGL16 is preferentially expressed in guard cells and down-regulated in response to drought stress. The expression of CYP707A3 and AAO3 in ABA metabolism and SDD1 in stomatal development was altered in agl16 and overexpression lines, making them potential targets of AGL16. Using chromatin immunoprecipitation, transient transactivation, yeast one-hybrid, and electrophoretic mobility shift assays, we demonstrated that AGL16 was able to bind the CArG motifs in the promoters of the CYP707A3, AAO3, and SDD1 and regulate their transcription, leading to altered leaf stomatal density and ABA levels. Taking our findings together, AGL16 acts as a negative regulator of drought resistance by modulating leaf stomatal density and ABA accumulation.

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MADS-box factor AGL16 negatively regulates drought resistance via stomatal density and stomatal movement

10.1101/723106 ◽

2019 ◽

Author(s):

Ping-Xia Zhao ◽

Zi-Qing Miao ◽

Jing Zhang ◽

Qian-Qian Liu ◽

Cheng-Bin Xiang

Keyword(s):

Drought Stress ◽

Drought Resistance ◽

Molecular Mechanisms ◽

Stomatal Density ◽

Stomatal Closure ◽

Negative Regulator ◽

Stomatal Development ◽

Mads Box ◽

Loss Of Function ◽

Research Attention

ABSTRACTDrought is one of the most severe environmental factors limiting plant growth and productivity. Plants respond to drought by closing stomata to reduce water loss. The molecular mechanisms underlying plant drought resistance are very complex and yet to be fully understood. While much research attention has been focused on the positive regulation of stomatal closure, less is known about its negative regulation, equally important in this reversible process. Here we show that the MADS-box transcriptional factor AGL16 acts as a negative regulator in drought resistance by regulating both stomatal density and movement. Loss-of-function mutantagl16was more resistant to drought stress with higher relative water content, which was attributed to a reduced leaf stomatal density and more sensitive stomatal closure due to a higher leaf ABA level compared with wild type, whileAGL16overexpression lines displayed the opposite phenotypes.AGL16is preferentially expressed in guard cells and down regulated in response to drought stress. The expression ofCYP707A3andAAO3in ABA metabolism andSDD1in stomatal development was altered by AGL16 as shown inagl16and overexpression lines. Chromatin immunoprecipitation, transient transactivation, and yeast-one-hybrid assays demonstrated that AGL16 bound the CArG motif in the promoter of theCYP707A3,AAO3, andSDD1to regulate their transcription, and therefore alter leaf stomatal density and ABA level. Taken together, AGL16 acts as a negative regulator of drought resistance by modulating leaf stomatal density and ABA accumulation.

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ABF3 enhances drought tolerance via promoting ABA-induced stomatal closure by directly regulating ADF5 in Populus euphratica

Journal of Experimental Botany ◽

10.1093/jxb/eraa383 ◽

2020 ◽

Vol 71 (22) ◽

pp. 7270-7285 ◽

Cited By ~ 1

Author(s):

Yanli Yang ◽

Hui-Guang Li ◽

Jie Wang ◽

Hou-Ling Wang ◽

Fang He ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Molecular Mechanisms ◽

Stomatal Closure ◽

Membrane Integrity ◽

Populus Euphratica ◽

Populus Tomentosa ◽

Limiting Factor ◽

Mobility Shift ◽

Cell Membrane Integrity

Abstract Water availability is a main limiting factor for plant growth, development, and distribution throughout the world. Stomatal movement mediated by abscisic acid (ABA) is particularly important for drought adaptation, but the molecular mechanisms in trees are largely unclear. Here, we isolated an ABA-responsive element binding factor, PeABF3, in Populus euphratica. PeABF3 was preferentially expressed in the xylem and young leaves, and was induced by dehydration and ABA treatments. PeABF3 showed transactivation activity and was located in the nucleus. To study its functional mechanism in poplar responsive to drought stress, transgenic triploid white poplars (Populus tomentosa ‘YiXianCiZhu B385’) overexpressing PeABF3 were generated. PeABF3 overexpression significantly enhanced stomatal sensitivity to exogenous ABA. When subjected to drought stress, PeABF3 overexpression maintained higher photosynthetic activity and promoted cell membrane integrity, resulting in increased water-use efficiency and enhanced drought tolerance compared with wild-type controls. Moreover, a yeast one-hybrid assay and an electrophoretic mobility shift assay revealed that PeABF3 activated the expression of Actin-Depolymerizing Factor-5 (PeADF5) by directly binding to its promoter, promoting actin cytoskeleton remodeling and stomatal closure in poplar under drought stress. Taken together, our results indicate that PeABF3 enhances drought tolerance via promoting ABA-induced stomatal closure by directly regulating PeADF5 expression.

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Morphophysiological and molecular effects of drought stress in rice

Annals of Plant Sciences ◽

10.21746/aps.2016.09.001 ◽

2016 ◽

Vol 5 (09) ◽

pp. 1409 ◽

Cited By ~ 17

Author(s):

Shamsun Nahar ◽

Jyotirmay Kalita ◽

Lingaraj Sahoo ◽

Bhaben Tanti*

Keyword(s):

Oxidative Stress ◽

Drought Stress ◽

Regulatory Network ◽

Molecular Mechanisms ◽

Stomatal Closure ◽

Green Revolution ◽

Yield Reduction ◽

Root And Shoot Length ◽

Rate Of Photosynthesis ◽

Effects Of Drought

Drought is a major abiotic stress that adversely affects the rice growth, mostly in the rainfed ecosystem that ultimately affects the biomass production and yield. Rice needs to adapt a series of physiological mechanisms with complicated regulatory network to fight and cope up with the unfavourable conditions due to drought stress. Morphological and physiological response in rice include inhibition of seed germination, slower growth rate, low root and shoot length, lower chlorophyll content, stomatal closure, lower rate of photosynthesis, yield reduction etc. Stress condition further results in development of response at the molecular level by the generation of reactive oxygen species (ROS) such as O2*-, H2O2, 1O2, OH* etc. which incites oxidative stress in the plants. Oxidative stress is overcome by the inherent capacity of plants to produce antioxidant species which may be enzymatic or non-enzymatic in nature. If however antioxidant defence mechanism cannot overpower the ROS generated, they cause oxidative damage to the plant tissues such as lipid peroxidation, protein oxidation, DNA damage, etc. resulting in cell death. Unlike other stresses, drought affects the physiology and biochemistry of the rice which adversely affects in the morphology and consequently delimits the yield of the plant. Therefore, understanding the morphological, biochemical and molecular mechanisms involved in rice against drought is utmost necessary for rice breeders to improve the rice for drought tolerant/resistance varieties for future green revolution. In this review, an attempt has been made to highlight the complex regulatory network involved in rice against drought with special emphasis on morphological, physiological and molecular mechanisms and to discuss the prospective and challenges for future plant breeders.

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The transcription factor ZmNAC49 reduces stomatal density and improves drought tolerance in maize

Journal of Experimental Botany ◽

10.1093/jxb/eraa507 ◽

2020 ◽

Author(s):

Yang Xiang ◽

Xiujuan Sun ◽

Xiangli Bian ◽

Tianhui Wei ◽

Tong Han ◽

...

Keyword(s):

Transcription Factor ◽

Drought Stress ◽

Stomatal Conductance ◽

Drought Tolerance ◽

Transpiration Rate ◽

Transcriptional Activation ◽

Stomatal Density ◽

Stomatal Development ◽

Expression Of Genes ◽

Growth Development

Abstract Drought stress severely limits the growth, development, and productivity of crops, and therefore understanding the mechanisms by which plants respond to drought is crucial. In this study, we cloned a maize NAC transcription factor, ZmNAC49, and identified its function in response to drought stress. We found that ZmNAC49 is localized in the nucleus and has transcriptional activation activity. ZmNAC49 expression is rapidly and strongly induced by drought stress, and overexpression enhances stress tolerance in maize. Overexpression also significant decreases the transpiration rate, stomatal conductance, and stomatal density in maize. Detailed study showed that ZmNAC49 overexpression affects the expression of genes related to stomatal development, namely ZmTMM, ZmSDD1, ZmMUTE, and ZmFAMA. In addition, we found that ZmNAC49 can directly bind to the promoter of ZmMUTE and suppress its expression. Taken together, our results show that the transcription factor ZmNAC49 represses ZmMUTE expression, reduces stomatal density, and thereby enhances drought tolerance in maize.

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Isolation, purification and characterization of an ascorbate peroxidase from celery and overexpression of the AgAPX1 gene enhanced ascorbate content and drought tolerance in Arabidopsis

BMC Plant Biology ◽

10.1186/s12870-019-2095-1 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 4

Author(s):

Jie-Xia Liu ◽

Kai Feng ◽

Ao-Qi Duan ◽

Hui Li ◽

Qing-Qing Yang ◽

...

Keyword(s):

Drought Stress ◽

Ascorbate Peroxidase ◽

Drought Resistance ◽

Stomatal Closure ◽

High Survival ◽

Gene Encoding ◽

Sds Page ◽

Relative Water ◽

New Evidence

Abstract Background Celery is a widely cultivated vegetable abundant in ascorbate (AsA), a natural plant antioxidant capable of scavenging free radicals generated by abiotic stress in plants. Ascorbate peroxidase (APX) is a plant antioxidant enzyme that is important in the synthesis of AsA and scavenging of excess hydrogen peroxide. However, the characteristics and functions of APX in celery remain unclear to date. Results In this study, a gene encoding APX was cloned from celery and named AgAPX1. The transcription level of the AgAPX1 gene was significantly upregulated under drought stress. AgAPX1 was expressed in Escherichia coli BL21 (DE3) and purified. The predicted molecular mass of rAgAPX1 was 33.16 kDa, which was verified by SDS-PAGE assay. The optimum pH and temperature for rAgAPX1 were 7.0 and 55 °C, respectively. Transgenic Arabidopsis hosting the AgAPX1 gene showed elevated AsA content, antioxidant capacity and drought resistance. Less decrease in net photosynthetic rate, chlorophyll content, and relative water content contributed to the high survival rate of transgenic Arabidopsis lines after drought. Conclusions The characteristics of APX in celery were different from that in other species. The enhanced drought resistance of overexpressing AgAPX1 in Arabidopsis may be achieved by increasing the accumulation of AsA, enhancing the activities of various antioxidant enzymes, and promoting stomatal closure. Our work provides new evidence to understand APX and its response mechanisms to drought stress in celery.

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An ABA-flavonoid relationship contributes to the differences in drought resistance between different sea buckthorn subspecies

Tree Physiology ◽

10.1093/treephys/tpaa155 ◽

2020 ◽

Author(s):

Guori Gao ◽

Zhongrui Lv ◽

Guoyun Zhang ◽

Jiayi Li ◽

Jianguo Zhang ◽

...

Keyword(s):

Drought Stress ◽

Rna Sequencing ◽

Drought Resistance ◽

Molecular Mechanisms ◽

Expression Patterns ◽

Normal Growth ◽

Carotenoid Biosynthesis ◽

Sea Buckthorn ◽

Mutual Regulation ◽

The Difference

Abstract Drought is the most severe abiotic stress and hinders the normal growth and development of plants. Sea buckthorn (Hippophae rhamnoides Linn.) is a typical drought-resistant tree species. In this study, the leaves of the H. rhamnoides ssp. sinensis (“FN”) and H. rhamnoides ssp. mongolica (“XY”) were selected during drought-recovery cycles for RNA sequencing, and physiological and biochemical analyses. The results revealed that drought stress significantly decreased leaf water potential, net photosynthetic rate, and stomatal conductance in both sea buckthorn subspecies. Similarly, the contents of flavone, flavonol, isoflavone and flavanone significantly decreased under drought stress in “XY.” Conversely, in “FN,” the flavone and abscisic acid (ABA) contents were significantly higher under drought stress and recovered after rehydration. Meanwhile, 4,618 and 6,100 differentially expressed genes (DEGs) were identified under drought stress in “FN” and “XY,” respectively. In total, 5,164 DEGs were observed in the comparison between “FN” and “XY” under drought stress. This was more than the 3,821 and 3,387 DEGs found when comparing the subspecies under control and rehydration conditions, respectively. These DEGs were mainly associated with carotenoid biosynthesis, flavonoid biosynthesis, photosynthesis, and plant hormone signal transduction. Six hub DEGs (ABCG5, ABCG22, ABCG32, ABCG36, ABF2 and PYL4) were identified to respond to drought stress based on WGCNA and BLAST analysis using DroughtDB. These six DEGs were annotated to play roles in the ABA-dependent signaling pathway. Sixteen RNA sequencing results involving eight genes and similar expression patterns (12/16) were validated using quantitative real-time PCR. The biochemical and molecular mechanisms underlying the regulation of drought responses by ABA and flavonoids in sea buckthorn were clarified. In this study, gene co-expression networks were constructed, and the results suggested that the mutual regulation of ABA and flavonoid signaling contributed to the difference in drought resistance between the different sea buckthorn subspecies.

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Overexpression of γ-glutamylcysteine synthetase gene from Caragana korshinskii decreases stomatal density and enhances drought tolerance

BMC Plant Biology ◽

10.1186/s12870-021-03226-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Baiyan Lu ◽

Xinjuan Luo ◽

Chunmei Gong ◽

Juan Bai

Keyword(s):

Drought Tolerance ◽

Mrna Expression ◽

Stress Responses ◽

Stomatal Density ◽

Negative Regulator ◽

Auxin Signaling ◽

Stomatal Development ◽

Endogenous Expression ◽

Caragana Korshinskii ◽

Glutamylcysteine Synthetase

Abstract Background Gamma-glutamylcysteine synthetase (γ-ECS) is a rate-limiting enzyme in glutathione biosynthesis and plays a key role in plant stress responses. In this study, the endogenous expression of the Caragana korshinskiiγ-ECS (Ckγ-ECS) gene was induced by PEG 6000-mediated drought stress in the leaves of C. korshinskii. and the Ckγ-ECS overexpressing transgenic Arabidopsis thaliana plants was constructed using the C. korshinskii. isolated γ-ECS. Results Compared with the wildtype, the Ckγ-ECS overexpressing plants enhanced the γ-ECS activity, reduced the stomatal density and aperture sizes; they also had higher relative water content, lower water loss, and lower malondialdehyde content. At the same time, the mRNA expression of stomatal development-related gene EPF1 was increased and FAMA and STOMAGEN were decreased. Besides, the expression of auxin-relative signaling genes AXR3 and ARF5 were upregulated. Conclusions These changes suggest that transgenic Arabidopsis improved drought tolerance, and Ckγ-ECS may act as a negative regulator in stomatal development by regulating the mRNA expression of EPF1 and STOMAGEN through auxin signaling.

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Activation of ACC synthase 2/6 increases stomatal density and cluster on the Arabidopsis leaf epidermis during drought

10.1101/2021.04.27.441570 ◽

2021 ◽

Author(s):

Ming-zhu Jia ◽

Ling-yun Liu ◽

Chen Geng ◽

Chun-peng Song ◽

Jing Jiang

Keyword(s):

Transcription Factor ◽

Drought Stress ◽

Stomatal Density ◽

Acc Synthase ◽

Individual Development ◽

Leaf Epidermis ◽

Stomatal Development ◽

Drought Conditions ◽

The Relationship ◽

Stomatal Lineage

AbstractIt is known that the transcription factor SPEECHLESS (SPCH) drives entry of epidermal cells into stomatal lineage, and that the activation of subtilisin-like protease SDD1 reduces stomatal density and cluster on the epidermis. However, there is still a big gap in our understanding of the relationship between stomatal development and the establishment of stomatal density and pattern, especially during drought. Interestingly, 1-aminocyclopropane-1-carboxylic acid (ACC) not only promotes stomatal development, but also is involved in the establishment of stomatal density and pattern. ACC generation comes from the activity of ACC synthase (ACS), while ACS activity could be mediated by drought. This work showed that the Arabidopsis SPCH activated ACS2/6 expression and ACC-dependent stomatal generation with an increase of stomatal density and cluster under drought conditions; and the possible mechanisms were that ACC-induced Ca2+ shortage in stomatal lineage reduced the inhibition of the transcription factor GT-2 Like 1 (GTL1) on SDD1 expression. These suggest that ACS2/6-dependent ACC accumulation integrated stomatal development with the establishment of stomatal density and pattern by mediating Ca2+ levels in stomatal lineage cells on the leaf epidermis, and this integration is directly related to the growth or survival of plants under escalated drought stress.HighlightACC synthase ACS2/6 activation integrated stomatal individual development with space setting between stomata by mediating Ca2+ levels in stomatal lineage on the leaf epidermis in response to drought.

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Complexity of ABA signaling for stomatal development and aperture regulation

10.1101/335810 ◽

2018 ◽

Author(s):

Pirko Jalakas ◽

Ebe Merilo ◽

Hannes Kollist ◽

Mikael Brosché

Keyword(s):

Stomatal Conductance ◽

Stomatal Density ◽

Stomatal Closure ◽

Critical Role ◽

Water Flux ◽

Stomatal Aperture ◽

Stomatal Development ◽

Triple Mutant ◽

Aperture Width ◽

Dependent Pathway

AbstractStomata, small pores on the surfaces of leaves formed by a pair of guard cells, adapt rapidly to changes in the environment by adjusting the aperture width. As a long term response, the number of stomata is regulated during stomatal development. The hormone abscisic acid (ABA) regulates both processes. In ABA mediated guard cell signaling the protein kinase OPEN STOMATA1 (OST1) has a central role, as stomatal closure in the ost1 mutant is impaired in response to ABA and to different environmental stimuli. We aimed to dissect the contribution of different ABA-related regulatory mechanisms in determining stomatal conductance, a combination of stomatal density and aperture width, and crossed the ost1 mutant with mutants that either decreased (aba3) or increased (cyp707a1/a3) the concentration of ABA in plants. The double mutant ost1 aba3 had higher stomatal conductance than either parent due to a combination of increased stomatal aperture width and higher stomatal density. In the triple mutant ost1 cyp707a1/a3 stomatal conductance was significantly lower compared to ost1-3 due to lower stomatal density. Further characterization of the single, double and triple mutants showed that responses to treatments that lead to stomatal closure were impaired in ost1 as well as ost1 aba3 and ost1 cyp707a1/a3 mutants, supporting a critical role for OST1 in stomatal aperture regulation. Based on our results, we suggest that there are two signaling pathways to regulate water flux from leaves i.e. stomatal conductance: an ABA-dependent pathway that determines stomatal density independent of OST1; and an OST1-dependent pathway that regulates rapid changes in stomatal aperture.

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A Soybean bZIP Transcription Factor GmbZIP19 Confers Multiple Biotic and Abiotic Stress Responses in Plant

International Journal of Molecular Sciences ◽

10.3390/ijms21134701 ◽

2020 ◽

Vol 21 (13) ◽

pp. 4701

Author(s):

Qing He ◽

Hanyang Cai ◽

Mengyan Bai ◽

Man Zhang ◽

Fangqian Chen ◽

...

Keyword(s):

Transcription Factor ◽

Drought Stress ◽

Pseudomonas Syringae ◽

Stress Responses ◽

Stomatal Closure ◽

Negative Regulator ◽

Marker Genes ◽

Genes Expression ◽

Salt And Drought Stress ◽

Salt And Drought Stresses

The basic leucine zipper (bZIP) is a plant-specific transcription factor family that plays crucial roles in response to biotic and abiotic stresses. However, little is known about the function of bZIP genes in soybean. In this study, we isolated a bZIP gene, GmbZIP19, from soybean. A subcellular localization study of GmbZIP19 revealed its nucleus localization. We showed that GmbZIP19 expression was significantly induced by ABA (abscisic acid), JA (jasmonic acid) and SA (salicylic acid), but reduced under salt and drought stress conditions. Further, GmbZIP19 overexpression Arabidopsis lines showed increased resistance to S. sclerotiorum and Pseudomonas syringae associated with upregulated ABA-, JA-, ETH- (ethephon-)and SA-induced marker genes expression, but exhibited sensitivity to salt and drought stresses in association with destroyed stomatal closure and downregulated the salt and drought stresses marker genes’ expression. We generated a soybean transient GmbZIP19 overexpression line, performed a Chromatin immunoprecipitation assay and found that GmbZIP19 bound to promoters of ABA-, JA-, ETH-, and SA-induced marker genes in soybean. The yeast one-hybrid verified the combination. The current study suggested that GmbZIP19 is a positive regulator of pathogen resistance and a negative regulator of salt and drought stress tolerance.

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