A Verticillium dahliae Pectate Lyase Induces Plant Immune Responses and Contributes to Virulence

Abstract

<i>Verticillium dahliae</i> is a wide-host-range fungal pathogen that causes soil-borne disease in hundreds of dicotyledonous hosts. In search of <i>V. dahliae</i> Vd991 cell death-inducing proteins, we identified a pectate lyase (VdPEL1) that exhibited pectin hydrolytic activity, which could induce strong cell death in several plants. Purified VdPEL1 triggered defense responses and conferred resistance to <i>Botrytis cinerea</i> and <i>V. dahliae</i> in tobacco and cotton plants. Our results demonstrated that the mutant VdPEL1^rec lacking the enzymatic activity lacked functions to induce both cell death and plant resistance, implying that the enzymatic activity was necessary. In addition, <i>VdPEL1</i> was strongly induced in <i>V. dahliae</i> infected <i>Nicotiana benthamiana</i> and cotton roots, and <i>VdPEL1</i> deletion strains severely compromised the virulence of <i>V. dahliae</i>. Our data suggested that VdPEL1 contributed to <i>V. dahliae</i> virulence and induced plant defense responses. These findings provide a new insight for the function of pectate lyase in the host-pathogen interaction.