Genome-wide analysis of the ALDH superfamily in Castanea mollissima highlights roles in abiotic stress responses

Abiotic stresses significantly impede the growth and yield of plants. In this context, the aldehyde dehydrogenase (ALDH) superfamily is integral to plant stress responses. To date, the systematic identification and functional characterization of the Castanea mollissima ALDH superfamily have not been reported. This study represents the first genome-wide systematic analysis of the CmALDH superfamily, identifying 25 CmALDH genes across nine families. Phylogenetic analysis suggests that members of the CmALDH superfamily underwent purifying selection during evolution, predominantly driven by dispersed duplication events. Collinearity analysis demonstrated both conservation and species-specific variations of ALDH genes between C. mollissima and several other species. Examination of cis -acting elements revealed that CmALDH promoter regions contain numerous elements associated with hormone response, abiotic stress, and light response. Transcriptome data analysis for six abiotic stresses (high temperature, low temperature, drought, salt, alkalinity, and shading) and RT−qPCR validation (high temperature, low temperature, salt, and alkaline stresses) revealed differential expression of various CmALDH genes, suggesting their potential roles in stress responses. This study systematically elucidates the evolutionary characteristics and abiotic stress response mechanisms of the CmALDH superfamily, providing valuable genetic resources and a theoretical basis for further analysis of the molecular underpinnings of stress resistance in woody plants and for the genetic enhancement of resistance in C. mollissima .