Comprehensive analysis of the AHL gene family in wheat (Triticum aestivum L.) reveals the association of TaAHL65 with drought tolerance

The AT-hook motif nuclear localized (AHL) proteins constitute a family of plant-specific transcription factors that play important roles in plant growth, development, and responses to environmental stresses. However, the AHL gene family has not been systematically characterized in wheat, and its potential functions in drought tolerance remain largely unknown. In this study, a genome-wide analysis identified 66 TaAHL genes in the wheat genome. Phylogenetic analysis classified these genes into two major clades and three structural types. Gene structure and conserved motif analyses revealed high conservation within each clade, whereas distinct structural differences were observed between clades. Promoter analysis identified numerous stress-responsive cis -acting elements, including MBS, DRE, LTR, and W-box elements, suggesting potential roles in abiotic stress responses. Synteny analysis revealed 64 segmentally duplicated gene pairs but no tandem duplication events, indicating that segmental duplication was the primary driver of TaAHL family expansion. Transcriptome and qRT-PCR analyses demonstrated that several TaAHL genes responded significantly to drought and salt stresses, among which TaAHL65 showed strong stress-induced expression. Functional characterization in transgenic Arabidopsis revealed that overexpression of TaAHL65 reduced drought tolerance, as indicated by increased MDA accumulation, decreased proline content, and reduced expression of drought-responsive genes. In wheat, TaAHL65 silencing enhanced drought tolerance, accompanied by higher relative water content (RWC), lower MDA accumulation and electrolyte leakage, increased proline content and antioxidant enzyme activities, and enhanced expression of drought-responsive genes. These findings indicate that TaAHL65 functions as a negative regulator of drought tolerance. This study provides a comprehensive characterization of the wheat AHL gene family and offers valuable insights into the evolutionary relationships and biological functions of TaAHL genes, thereby providing a potential genetic target for improving abiotic stress tolerance in wheat.