IbMYB11 Involved in Drought Stress Responses Through Association with Flavonoid Metabolism in Sweet Potato

Abstract

Sweet potato (Ipomoea batatas (L.) Lam.) is a high-yielding crop that serves as both a food source and a raw material for industrial processing. Drought stress severely impairs sweet potato yield and quality. A MYB-type transcription factor, IbMYB11, was previously identified as a differentially expressed gene induced by drought stress from our previous comparative transcriptome analysis. In this study, we characterized its potential roles in drought tolerance and flavonoid metabolism in sweet potato. Subcellular localization analysis revealed that IbMYB11 localizes to the nucleus. Overexpression of IbMYB11 enhanced SOD and POD activities in transgenic sweet potato plants under drought stress, whereas these activities were significantly reduced in IbMYB11-RNAi plants, suggesting that IbMYB11 may confer drought tolerance by improving the capacity to scavenge reactive oxygen species. Transcriptome and metabolome analyses of IbMYB11-OE, IbMYB11-RNAi, and wild-type plants under simulated drought stress further revealed that the differentially expressed genes (DEGs) from all comparison groups were enriched in the flavonoid biosynthesis pathway, and nine flavonoid metabolites were identified among the differentially accumulated metabolites. Furthermore, differentially expressed TFs and flavonoid metabolites were jointly subjected to WGCNA, yielding 12 hub genes and modules significantly associated with flavonoid metabolites. Collectively, this study demonstrates that IbMYB11 improved drought tolerance, likely in part via its association with flavonoid metabolism, and providing valuable genetic resources for molecular design breeding of drought-resistant sweet potato.