The Aldehyde Dehydrogenase Superfamily in Brassica napus L.: Genome-Wide Identification and Expression Analysis Under Low-Temperature Conditions

The Aldehyde Dehydrogenase (ALDH) superfamily comprises a group of NAD+ or NADP+-dependent enzymes that play essential roles in responding to abiotic stresses in plants. In Brassica napus L., however, the increasing frequency of extremely low temperatures during winter in recent years has significantly affected both yield and quality. This study conducted a genome-wide screening of ALDH superfamily genes, analyzing their gene structures, evolutionary relationships, protein physicochemical properties, and expression patterns under low-temperature stress to explore the function of the ALDH superfamily gene in cold tolerance in Brassica napus L. A total of six BnALDH genes with significant differences in expression levels were verified utilizing quantitative real-time polymerase chain reaction (qRT-PCR), revealing that BnALDH11A2, BnALDH7B2, BnALDH3F5, BnALDH12A3, BnALDH2B6, and BnALDH7B3 all exhibited higher expression in cold-tolerant material 24W233 compared with cold-sensitive material 24W259. Additionally, a single nucleotide polymorphism (SNP) in the BnALDH11A2 promoter region shows differences between the cold-tolerant (24W233) and the cold-sensitive (24W259) Brassica napus varieties, and it may be associated with the cold tolerance of these two varieties. This comprehensive analysis offers valuable insights into the role of ALDH family genes in low-temperature stress adaptation in Brassica napus and offers genetic resources for the development of novel cold-tolerant cultivars.