Identification of the CLE gene family in Gossypium hirsutum and functional analysis of the drought resistance of GhCLE13

The CLAVATA3/Embryo surrounding region-related (CLE) peptide family is the largest family of small peptide hormones in plants. It is widely present in various plant species and participates in multiple important life activities of plants. In this study, the CLE gene family was identified at the genome-wide level in Gossypium hirsutum, and their gene structures, cis-acting elements in the promoter, protein physicochemical properties, and phylogenetic analysis of GhCLE gene family members were analyzed. The expression profiles of GhCLE gene family members in various tissues were constructed using RNA-seq data. Finally, the drought resistance function of the screened GhCLE genes was validated by virus-induced gene silencing (VIGS) technology. The results showed that a total of 40 GhCLE genes were identified in the whole genome of Gossypium hirsutum. The structures of GhCLE genes were relatively simple, with 32 GhCLE genes having no introns, and their protein sequences all contained a 12 aa CLE domain. The GhCLE gene promoter region contains a variety of cis-acting elements related to light response, stress response, hormone response, and development. The gene expression profile showed that the GhCLE gene was expressed in multiple tissues of Gossypium hirsutum, with GhCLE13-D-2 being specifically expressed in root tissue and induced by drought. The function of the GhCLE13-D-2 gene in improving cotton drought resistance was validated through VIGS technology and the measurement and comparison of MDA content. This study provides a new theoretical basis for the in-depth study of small peptides, such as CLE, in plant drought resistance and cotton germplasm innovation.