Transcription factor BnaDIV1 positively regulates alkaline tolerance in Brassica napus

Alkaline stress severely restricts plant growth and crop productivity. MYB transcription factors (TFs) act as critical regulators of plant abiotic stress tolerance, while the functions of MYB family genes in alkaline stress adaptation of Brassica napus remain largely elusive. Here, we found that the four BnaDIV1s , encoding R-R-type MYB-like TFs with conserved MYB functional domains and a conserved SHAQKYF motif, exhibited high homology with Arabidopsis AtDIV1. Tissue expression analyses revealed that BnaDIV1s were predominantly expressed in roots and markedly upregulated upon NaHCO 3 treatment. Overexpression of each BnaDIV1 paralog improved alkaline stress tolerance in Arabidopsis, whereas loss-of-function of AtDIV1 led to pronounced hypersensitivity to alkaline stress. Further analysis showed that BnaA03.DIV1 overexpression in B. napus enhanced alkaline stress resistance by directly modulating the expression of BnaA10.CHYR1 and BnaA04.CSD2 , indirectly regulating multiple stress-associated genes, and reinforcing antioxidant defense systems to alleviate oxidative damage. Collectively, these findings advance our understanding of the biological functions and regulatory mechanisms of BnaDIV1s , and provide valuable genetic resources for breeding alkaline-tolerant rapeseed germplasms.