Targeting BnNAC038 improves drought tolerance with low yield penalty in Brassica napus

Drought stress severely limits crop productivity in Brassica napus, yet strategies to enhance drought tolerance without compromising yield remain elusive. Here, we identify BnNAC038 as a negative regulator of drought responses in Brassica napus. CRISPR/Cas9-generated bnnac038 mutants exhibited improved drought survival, reduced water loss, and enhanced stomatal closure under drought conditions compared to wild-type (WT) plants. RNA-sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq) analyses revealed that BnNAC038 directly represses drought-responsive genes, including BnSnRK2.6 (a key ABA signaling kinase), and genes involved in photosynthesis (BnPPC2) and gluconeogenesis (BnPGK). Field trials demonstrated that bnnac038 plants exhibit enhanced photosynthesis, accumulate more sucrose and glucose under drought, and exhibit increased biomass and seed yield compared to WT. Genetic interaction studies further showed that BnSnRK2.6 acts downstream of BnNAC038 to mediate drought tolerance. Our results indicate that targeted editing of BnNAC038 enhances drought tolerance while minimizing yield loss, providing a new strategy for developing drought-resilient Brassica napus varieties with minimal yield penalty.