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The trithorax group (TrxG) complex is an important protein in the regulation of plant histone methylation. The ABSENT, SMALL, OR HOMEOTIC DISCS 1 (ASH1) gene family, as important family members of the TrxG complex, has been shown to regulate tolerance to abiotic stress and growth and development in many plants. In this study, we identified nine GhASH1s in upland cotton. Bioinformatics analysis revealed that GhASH1s contain a variety of cis-acting elements related to stress resistance and growth and development. The transcriptome expression profiles revealed that GhASHH1.A and GhASHH2.A genes expression were upregulated in flower organs and in response to external temperature stress. The results of virus-induced gene silencing (VIGS) indicated that GhASHH1.A and GhASHH2.A genes silencing reduced the ability of cotton to adapt to temperature stress and delayed the development of the flowering phenotype. We also showed that the silencing of these two target genes did not induce early flowering at high temperature (32 °C), suggesting that GhASHH1.A and GhASHH2.A might regulate cotton flowering in response to temperature. These findings provide genetic resources for future breeding of early-maturing and temperature-stress-tolerant cotton varieties. [ABSTRACT FROM AUTHOR]

Verticillium dahliae is a soil‐borne, phytopathogenic fungus that causes Verticillium wilt in cotton. Salt tolerance of cotton plants suffering from Verticillium wilt was significantly improved, but the mechanism is unknown. In this study, we built a symbiont named Cotton≡VD by immersing cotton plant roots into Verticillium dahliae liquid for four days. This resulted in a strong interaction between hyphae and the cotton roots. Under NaCl treatment for 24 h, the Cotton≡VD displayed less leaf wilting and improved root growth compared with the control. Biochemical tests of SOD, POD and CAT showed significant overexpression in Cotton≡VD compared with CK. RNA‐seq data analysis of Cotton≡VD indicated a novel 'galactose metabolism pathway' in the KEGG database, in which two key genes, GolS2 and RFS5, were significantly differentially expressed. Symbiotic metabolites inositol galactosyl could be transformed into raffinose to scavenge free radicals and participate in plant osmotic regulation to alleviate salt stress in Cotton≡VD. Functional analysis indicated that silencing of the target gene GhRFS (RFS5) led to a decrease of raffinose content and salt tolerance as compared with CK. Cotton≡VD can significantly improve cotton seedling salt tolerance through improving raffinose content, providing new insights into the salt tolerance mechanism and new salt‐tolerant material in the future. [ABSTRACT FROM AUTHOR]

As one of the cash crops, cotton is facing the threat of abiotic stress during its growth and development. It has been reported that melatonin is involved in plant defense against salt stress, but whether melatonin can improve cotton salt tolerance and its molecular mechanism remain unclear. We investigated the role of melatonin in cotton salt tolerance by silencing melatonin synthesis gene and exogenous melatonin application in upland cotton. In this study, applicating of melatonin can improve salt tolerance of cotton seedlings. The content of endogenous melatonin was different in cotton varieties with different salt tolerance. The inhibition of melatonin biosynthesis related genes and endogenous melatonin content in cotton resulted in the decrease of antioxidant enzyme activity, Ca2+ content and salt tolerance of cotton. To explore the protective mechanism of exogenous melatonin against salt stress by RNA-seq analysis. Melatonin played an important role in the resistance of cotton to salt stress, improved the salt tolerance of cotton by regulating antioxidant enzymes, transcription factors, plant hormones, signal molecules and Ca2+ signal transduction. This study proposed a regulatory network for melatonin to regulate cotton's response to salt stress, which provided a theoretical basis for improving cotton's salt tolerance. [ABSTRACT FROM AUTHOR]

As one of the cash crops, cotton is facing the threat of abiotic stress during its growth and development. It has been reported that melatonin is involved in plant defense against salt stress, but whether melatonin can improve cotton salt tolerance and its molecular mechanism remain unclear. We investigated the role of melatonin in cotton salt tolerance by silencing melatonin synthesis gene and exogenous melatonin application in upland cotton. In this study, applicating of melatonin can improve salt tolerance of cotton seedlings. The content of endogenous melatonin was different in cotton varieties with different salt tolerance. The inhibition of melatonin biosynthesis related genes and endogenous melatonin content in cotton resulted in the decrease of antioxidant enzyme activity, Ca 2+ content and salt tolerance of cotton. To explore the protective mechanism of exogenous melatonin against salt stress by RNA-seq analysis. Melatonin played an important role in the resistance of cotton to salt stress, improved the salt tolerance of cotton by regulating antioxidant enzymes, transcription factors, plant hormones, signal molecules and Ca 2+ signal transduction. This study proposed a regulatory network for melatonin to regulate cotton's response to salt stress, which provided a theoretical basis for improving cotton's salt tolerance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zhang, Fan, Rui, Zhang, Xu, Dai, Chen, Lu, Wang, Wang, Wang, Wang, Wang, Chen, Guo, Zhao and Ye.)