GhODO1, an R2R3-type MYB transcription factor, positively regulates cotton resistance to Verticillium dahliae via the lignin biosynthesis and jasmonic acid signaling pathway

In plants, MYB transcription factors play diverse roles in growth, development, and response to abiotic and biotic stresses. However, the signaling processes of these transcription factors in defense against pathogen attacks remain largely unknown. This study isolated a novel R2R3-type MYB transcription factor GhODO1 from cotton (Gossypium hirsutum) and functionally characterized its positive role in tolerance to Verticillium dahliae. GhODO1 was induced by V. dahliae and jasmonic acid (JA) and transient expression of fused GhODO1-GFP in onion epidermal cells showed that GhODO1 protein was localized in the cell nucleus. Knockdown of GhODO1 significantly reduced the resistance of cotton to V. dahliae, whereas GhODO1 ectopic overexpression in Arabidopsis conferred enhanced resistance to V. dahliae. Lignin deposition was significantly decreased in GhODO1-silenced cotton plants after V. dahliae inoculation and mock treatment. The expression levels of genes and activities of enzymes involved in lignin biosynthesis were reduced in GhODO1-silenced cotton plants compared to the TRV:00. Yeast one-hybrid assays revealed that GhODO1 protein interacts with the promoters of lignin biosynthesis-related genes Gh4CL1 and GhCAD3, directly activates their expression, and enhances total lignin accumulation. Moreover, GhODO1 silencing compromised JA-mediated defense signaling and JA accumulation. These results show that GhODO1 is involved in cotton resistance to V. dahliae by involving the lignin biosynthesis and the JA signaling pathway.