Comprehensive analysis of Brassica napus aldehyde dehydrogenase superfamily genes and demonstration of BnALDH7B2 in clubroot resistance

Abstract

Oilseed rapa (Brassica napus), an important oil crop worldwide, is often threatened by various adversity stresses, especially Plasmodiophora brassicae, resulting in abnormal growth and decreased yield. The aldehyde dehydrogenase (ALDH) family is crucial for plant growth and environmental stress adaptations. Nevertheless, BnALDH members and their responses to P. brassicae are unclear in B. napus. Here, 53 B. napus ALDH members were identified and classified into 10 subfamilies. Collinearity analyses revealed that the BnALDHs gene family primarily underwent expansion through segmental duplication. Structural analyses illustrated that the BnALDHs in each specific subfamily were relatively conserved. Analysis of cis-elements in BnALDH promoter regions revealed the presence of multiple elements related to stress response and plant hormones. Transcriptome analyses indicated that BnALDHs were expressed throughout B. napus multiple tissues and growth stages. Most BnALDHs were differentially expressed under different stress treatments, with BnALDH7B2 significantly upregulated during P. brassicae stress. In addition, the BnALDH7B2 overexpression transgenic plants conferred tolerance to P. brassicae stress. Molecular docking results showed that BnALDH7B2 was more functionally dependent on NAD+ than on NADP+, while phenylacetaldehyde, benzaldehyde, trans-2-nonenal, α-aminoadipate-semialdehyde, and 4-guanidinobutyraldehyde could potentially be used as substrates for BnALDH7B2. The results provide insights into the function of BnALDHs in B. napus, serving as a baseline for identifying the functional role of BnALDH7B2 under P. brassicae stress.