Genome-Wide Identification and Expression Analysis of Gene Family Members in Cotton under Abiotic Stress.

Adenosine kinase (ADK) is a key enzyme widely distributed in plants, playing an important role in maintaining cellular energy homeostasis and regulating plant growth, development, and responses to environmental stresses. However, research on genes in cotton (), an economically significant crop, has been limited. This study identified 92 genes from four cotton species (, , , and ) using HMMER and Local BLASTP methods and classified them into six groups. Chromosomal localization revealed a random distribution of genes in , with 13 genes located on the At subgenome and 14 genes on the Dt subgenome. Gene structure analysis showed consistency in exon-intron organization within subgroups, while conserved motif analysis identified subgroup-specific motifs, indicating functional diversity. Synteny and collinearity mapping analysis revealed that the primary expansion mechanisms of the gene family in cotton are polyploidy and segmental duplication. Cis-regulatory elements in promoters were classified into light response, hormone response, developmental regulation, and stress response. We also analyzed the expression patterns of genes under a low temperature (4 °C) and drought conditions. Most genes responded to cold stress with different expression patterns, indicating their roles in rapid response and long-term cold adaptation. Under drought stress, expression patterns varied, with some genes showing sustained high expression levels. The qRT-PCR validation of transcriptomic data confirmed the stress-induced expression patterns of selected genes. Functional analysis through the VIGS silencing of demonstrated its importance in cold and drought stress responses, with silencing resulting in poor growth under stress, highlighting its significance in stress tolerance. This study provides a basis for further understanding the evolutionary relationships and functions of the cotton gene family.