Comprehensive RNA-Seq analysis revealed molecular pathways and genes associated with drought tolerance in Morus alba...

Drought stress driven by global climate change critically restricts mulberry growth. The identification of drought-responsive genes in the Yunnan-adapted Yunsang cultivar is essential for mitigating environmental constraints on sericulture. In this study, seedlings of the mulberry cultivar Yunsang-2 were subjected to drought stress under greenhouse conditions. Leaf samples were collected for physiological analysis (proline content and CAT and POD activities) and transcriptome profiling via RNA-Seq. The results revealed that compared with the plants in the CK group, the drought-stressed plants had significantly increased CAT and POD activities by 7 days post-stress (DPS) and accumulated markedly greater amounts of proline at 9 and 12 DPS. Transcriptomic analysis revealed that drought resistance involves key genes enriched in the abscisic acid (ABA), gibberellin (GA), and brassinosteroid (BR) signaling pathways, such as PYR, ABF, PIF3, and BSK. Furthermore, we identified 156 TFs as potential regulatory hubs. Among these genes, MnERF21 was tentatively identified as a candidate positive regulator of drought resistance. Our findings systematically elucidate the molecular mechanisms underlying drought tolerance in mulberry and provide novel insights into the drought resistance strategies of Yunnan-adapted germplasms.