Unveiling the Role of in Cotton Salt Stress Tolerance: A Comprehensive Genomic and Functional Analysis of Genes.

Proline, a critical osmoregulatory compound, is integral to various plant stress responses. The gene, which encodes the rate-limiting enzyme in proline biosynthesis, known as ∆1-pyrroline-5-carboxylate synthetase, is fundamental to these stress response pathways. While the functions of genes in plants have been extensively documented, their specific roles in cotton remain inadequately characterized. In this study, we identified 40 genes across four cotton species with diverse sequence lengths and molecular weights. Phylogenetic analysis of 100 genes from nine species revealed three subgroups, with closely related to . Collinearity analysis highlighted significant differences in collinear gene pairs, indicating evolutionary divergence among genes in tetraploid and diploid cotton. Exon-intron structures and conserved motifs correlated with phylogenetic relationships, suggesting functional differentiation. Stress-responsive elements in promoters suggest involvement in abiotic stress. Expression analysis under salt stress revealed differential expressions of genes, with emerging as a potential key regulator. Virus-induced gene silencing confirmed the pivotal role of in cotton's salt stress response, as evidenced by increased salt sensitivity in the silenced plants. This study enhances our understanding of the functional diversity and roles of genes in cotton under stress conditions.