GhUMC1, a blue copper-binding protein, regulates lignin synthesis and cotton immune response.

Verticillium wilt caused by the soil-borne fungus Verticillium dahliae is a serious problem for the sustainable production of cotton. The mechanism of cotton resistance to V. dahliae is unclear, which makes it is difficult to improve cotton resistance breeding. In this study, we characterized an umecyanin-like gene GhUMC1 in cotton, which is homologous to the AtBCB gene in Arabidopsis. It is predominantly expressed in roots and responds to pathogen infection. Knock-down of GhUMC1 increases plant susceptibility to V. dahliae. Expression levels of genes in the JA and SA signaling pathways in roots were down-regulated in GhUMC1-silenced plants. The transcripts of lignin synthesis genes, such as C4H, HCT, CCoAOMT and CAD, were also decreased in GhUMC1 knock-down seedlings, as was lignin content. Interestingly, knock-down of the GhUMC1 also decreased the contents of H202 compared with the control. Our results suggest that GhUMC1 is involved in cotton resistance to V. dahliae by the regulation of the JA signaling pathway and lignin metabolism.