, , and improve resistance to salt and cold stress in upland cotton.

Introduction: Abiotic stress during growth readily reduces cotton crop yield. The different survival tactics of plants include the activation of numerous stress response genes, such as ().

Methods: In this study, the gene family of upland cotton was identified and analyzed by bioinformatics method, three salt-tolerant and cold-resistant genes were screened. The expression of , and in upland cotton was silenced by virus-induced gene silencing (VIGS) technique. The physiological and biochemical indexes of plants and the expression of related stress-response genes were detected before and after gene silencing. The effects of , and on salt and cold resistance of upland cotton were further verified.

Results And Discussion: We discovered 12, 6, and 6 genes in , and , respectively. Chromosomal localization indicated that the retention and loss of genes on homologous chromosomes did not have a clear preference for the subgenomes. Collinearity analysis suggested that segmental duplications were the main force for gene amplification. The upland cotton genes , and are highly expressed in roots, and is also strongly expressed in the pistil. Transcriptome data and qRT‒PCR validation showed that abiotic stress strongly induced , and . Under salt stress and low-temperature stress conditions, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and the content of soluble sugar and chlorophyll decreased in , and -silenced cotton plants compared with those in the control (TRV: 00). Moreover, -, - and -silenced cotton plants exhibited greater malondialdehyde (MDA) levels than did the control plants. Moreover, the expression of stress marker genes (, , , , , , , and ) decreased significantly in the three target genes of silenced plants following exposure to stress. These results imply that the , and genes may be regulators of salt stress and low-temperature stress responses in upland cotton.