BnaMYB52 negatively regulates drought resistance by controlling stomatal and non-stomatal water loss in <i>Brassica napus</i>

Brassica napus is one of the most important oil crops worldwide, and its production is severely threatened by drought stress. Breeding drought-resistant cultivars is needed to cope with global climate change. However, few drought resistance regulators have been identified, and the molecular mechanism of drought resistance is largely unknown in B. napus. Here, we characterized a typical R2R3-MYB transcription factor, BnaMYB52, as a negative regulator of drought resistance in B. napus. The disruption of BnaMYB52 resulted in enhanced drought resistance, whereas overexpression of BnaA09.MYB52 reduced drought resistance. Further analyses showed that BnaMYB52 affects leaf water loss from both stomata and the cuticle to negatively regulate drought resistance. We demonstrated that BnaMYB52 acts as a transcription repressor regulating the expression of the downstream targets BnaMYB96 and BnaMYB30, controlling both ABA signaling and wax biosynthesis, and BnaMYC2, controlling stomatal density. This study uncovers the molecular mechanism of BnaMYB52-regulated drought resistance and provides a genetic resource for the molecular breeding of drought-resistant B. napus cultivars.