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MYB transcription factors play a vital role in response to stress in plant. MYB-CC transcription factors belong to MYB transcription factors, which contain a conserved MYB DNA-binding domain and a coiled-coil (CC) domain. MYB-CC transcription factors participate in the process of plant drought tolerance. However, the underlying molecular mechanisms of ZmMYB-CC in regulating drought tolerance are still largely unknown. Here, we found that ZmMYB-CC10 enhanced drought tolerance by reducing oxidative damage in maize. Further, ZmMYB-CC10 improves the activity of APX and decreases the content of H 2 O 2. Overexpression of ZmMYB-CC10 increases the expression of ZmAPX4 under drought stress. Luciferase assays and Yeast one-hybrid assays (Y1H) showed that ZmMYB-CC10 activates the expression of ZmAPX4 by directly binding to its promoter. Taken together, our results demonstrate that ZmMYB-CC10 enhances tolerance to drought stress by directly activating ZmAPX4 expression, thereby reducing H 2 O 2 content. • ZmMYB-CC10 enhances drought tolerance by reducing oxidative damage in maize. • ZmMYB-CC10 decreases the content of H 2 O 2 by increasing the activity of APX under drought stress. • ZmMYB-CC10 directly binds to ZmAPX4 promotor and activates its expression. [ABSTRACT FROM AUTHOR]

Salinity has become a crucial environmental factor that restricts plant growth, development, and productivity. Nevertheless, the mechanisms by which plants react to salt stress remain inadequately comprehended. In this study, we identified maize brassinosteroid-signaling kinase gene ZmBSK7 which is homologous to AtBSK1. Our results showed that ZmBSK7 is induced by salt stress and ZmBSK7 localizes in the plasma membrane. ZmBSK7 overexpression increases salt tolerance, while its knockdown decreases salt tolerance in maize. ZmBSK7 reduces the malondialdehyde (MDA) content and the percentage of electrolyte leakage, and also elevates the activities of antioxidant enzymes. Furthermore, ZmBSK7 promotes K+ content accumulation and reduces Na+/K+ ratio. Further found that ZmBSK7 physically interacts with K+ efflux antiporter 2 (ZmKEA2) in vivo and in vitro. Salt stress also increased the expression of ZmKEA2. Thus, ZmBSK7 improves salt tolerance in maize by affecting ZmKEA2 expression to promote K+ content accumulation and reduce Na+/K+ ratio. This study enhances the comprehension of BSK proteins and establishes a theoretical foundation for investigating salt stress tolerance in plants. • ZmBSK7 positively enhance the tolerance of salt stress in maize. • Overexpression of ZmBSK7 improves the activities of antioxidant enzymes and maintaining a balance of Na+ and K+. • ZmBSK7 physically interacts with ZmKEA2 in vivo and in vitro. [ABSTRACT FROM AUTHOR]

NAC (NAM, ATAF1/2, and CUC2) transcription factors play vital roles in response to multiple abiotic stresses. Our previous study has demonstrated that ZmNAC84, a maize NAC transcription factor, enhanced the drought tolerance by increasing abscisic acid (ABA)-induced antioxidant enzyme activities of APX and SOD, and Ser-113, a key phosphorylation site, of ZmNAC84 played an important role in this process. However, the target gene of ZmNAC84 in this process is still unknown. Here, we found that ZmNAC84 only regulated the luciferase activity driven by ZmSOD2 promoter in tobacco. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assay showed that ZmNAC84 directly bound to the CACGTG motif of ZmSOD2 promoter. Furthermore, phosphorylation of ZmNAC84 at Ser-113 up-regulated the ZmSOD2 expression by enhancing the DNA binding ability of ZmNAC84 to ZmSOD2 promoter and improved the drought tolerance. Taken together, our results demonstrate that ZmNAC84 directly regulates ZmSOD2 expression to enhance drought tolerance and Ser-113 of ZmNAC84 is crucial in this process. • ZmNAC84 directly binds to ZmSOD2 promoter in vivo and in vitro. • Phosphorylation of ZmNAC84 at Ser-113 up-regulates the ZmSOD2 expression. • Phosphorylation of ZmNAC84 at Ser-113 enhances the DNA binding ability of ZmNAC84. [ABSTRACT FROM AUTHOR]

Calcium/calmodulin-dependent protein kinase (CCaMK) has been shown to play important roles in brassinosteroid (BR)-induced antioxidant defense and enhancing the tolerance of plants to drought stress. The autophosphorylation of CCaMK is a key step for the activation of CCaMK, thus promoting substrate phosphorylation. However, how CCaMK autophosphorylation function in BR-induced antioxidant defense is not known yet. Here, seven potential autophosphorylation sites of ZmCCaMK were identified using mass spectroscopy (liquid chromatography-tandem mass spectrometry [LC-MS/MS]) analysis. The transient gene expression analysis in maize protoplasts showed that Thr420 and Ser454 of ZmCCaMK were important for BR-induced antioxidant defense. Furthermore, Thr420 and Ser454 of ZmCCaMK were crucial for improving drought tolerance and alleviating drought induced oxidative damage of plants via overexpressing various mutant versions of ZmCCaMK in tobacco (Nicotiana tabacum). Mutations of Thr420 and Ser454 in ZmCCaMK substantially blocked the autophosphorylation and substrate phosphorylation of ZmCCaMK in vitro. Taken together, our results demonstrate that Thr420 and Ser454 of ZmCCaMK are crucial for BR-induced antioxidant defense and drought tolerance through modulating the autophosphorylation and substrate phosphorylation activities of ZmCCaMK. • Thr420 and Ser454 of ZmCCaMK are crucial for BR-induced antioxidant defense in maize. • Phosphorylation of Thr420 and Ser454 of ZmCCaMK enhance drought tolerance in plants. • T420A and S454A of ZmCCaMK affect the kinase activity of ZmCCaMK in vitro. [ABSTRACT FROM AUTHOR]

Abstract The alteration of cell wall component and structure is an important adaption to saline environment. Pectins, a major cell wall component, are often present in a highly methylesterified form. The level of methyl esterification determined by pectin methylesterases (PMEs) influences many important wall properties that are believed to relate to the adaption to saline stress. However, little is known about the function of PMEs in response to salt stress. Here, we established a link between pectin methylesterase31 (PME31) and salt stress tolerance. Salt stress significantly increases PME31 expression. PME31 is located in the plasma membrane and the expression level of PME31 was high in dry seeds. Knock-down mutants in PME31 conferred hypersensitive phenotypes to salt stress in seed germination and post-germination growth. Real-time PCR analysis revealed that the transcript levels of several stress genes (DREB2A , RD29A and RD29B) are lower in pme31-2 mutant than that in the wild type in response to salt stress. These results suggested that PME31 could positively modulate salt stress tolerance. Highlights • Salt stress could significantly increase PME31 expression. • pme31 mutants are hypersensitive to salt stress. • PME31 positively modulate the expression levels of salt stress-induced genes. [ABSTRACT FROM AUTHOR]

As the major resource of reactive oxygen species (ROS), the NADPH oxidases (Rbohs) have been shown to play important roles in plant cells under normal growth and stress conditions. Although many family members of Rbohs were studied, little is known about the function of RbohI in Arabidopsis thaliana . Here, we report that exogenous ABA application decreases RbohI expression and mannitol significantly increases RbohI expression at transcript level. The RbohI transcripts were strongly detected in dry seeds and roots. The loss-of-function mutant rbohI exhibited sensitivity to ABA and mannitol stress during germination. Furthermore, the lateral root growth of rbohI was severely inhibited after treatment with mannitol stress. Overexpression of RbohI in Arabidopsis significantly improves the drought tolerance. Moreover, more H 2 O 2 accumulated in RbohI overexpressors than in wild type plants in response to mannitol stress. Our conclusion is that AtRbohI functions in drought-stress response in Arabidopsis thaliana. [ABSTRACT FROM AUTHOR]