Verticillium dahliae Elicitor VdSP8 Enhances Disease Resistance Through Increasing Lignin Biosynthesis in Cotton.

ABSTRACT Verticillium wilt caused by the soil‐borne fungus <italic>Verticillium dahliae</italic> Kleb., is a destructive plant disease that instigates severe losses in many crops. Improving plant resistance to Verticillium wilt has been a challenge in most crops. In this study, a <italic>V. dahliae</italic> secreted protein VdSP8 was identified and shown to activate hyper‐sensitive response (HR) and systemic acquired resistance (SAR) to <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> DC3000 (<italic>Pst</italic> DC3000) and <italic>Botrytis cinerea</italic> in tobacco plants. We identified a β‐glucosidase named GhBGLU46 as a cotton plant target of VdSP8. VdSP8 interacts with GhBGLU46 both in vivo and in vitro and promotes the β‐glucosidase activity of GhBGLU46. Silencing of <italic>GhBGLU46</italic> reduced the expression of genes involved in lignin biosynthesis, such as <italic>GhCCR4</italic>, <italic>GhCCoAOMT2</italic>, <italic>GhCAD3</italic> and <italic>GhCAD6</italic>, thus decreasing lignin deposition and increasing Verticillium wilt susceptibility. We have shown that GhBGLU46 is indispensable for the function of VdSP8 in plant resistance. These results suggest that plants have also evolved a strategy to exploit the invading effector protein VdSP8 to enhance plant resistance. [ABSTRACT FROM AUTHOR]