Identification of the full-length GbERD7 gene family in Gossypium barbadense and functional analysis of the role of the GbERD7g gene in drought and salt tolerance.

ERD (early response to dehydration) genes are promptly upregulated under dehydration stress and are pivotal in plant development. Nonetheless, the precise impact of the ERD7 gene on the response of cotton to abiotic stress remains unclear. The physical and chemical characteristics, gene architecture, gene collinearity, and transcriptomic profiles were examined. Using bioinformatics techniques, we investigated the evolutionary relationships among the genes within the GbERD7 gene family of sea island cotton. The GbERD7 genes are unevenly distributed across the seven chromosomes of sea island cotton, with multiple gene duplications. The GbERD7 gene family was subjected to phylogenetic analysis, leading to the classification of its members into the SENA and SENB subfamilies. The expression of the GbERD7 genes was investigated in relation to heat, low-temperature, salt (NaCl), and polyethylene glycol (PEG) treatments. Some genes presented greater expression in specific organs and different periods of fiber development. The functional role of GbERD7g was subsequently investigated using molecular biological techniques. GbERD7g exhibited pronounced expression in sea island cotton leaves and was upregulated following exposure to PEG, NaCl, and ABA. Subcellular localization studies revealed that the GbERD7g protein is located within the nucleus as well as the plasma membrane of the cell. When the GbERD7g gene was silenced under drought and salt stress, the sea island cotton plants were significantly less resistant to drought and salinity and exhibited lower survival than the control plants. The proline levels, catalase activity, and superoxide dismutase activity were reduced, and the malondialdehyde and hydrogen peroxide levels were elevated. In addition, compared with those in the control plants, the expression of all three stress-responsive genes, namely, GbRD22, GbRD26, and GbCDPK1, was significantly lower in the mutant plants.