The Botrytis cinerea Xylanase BcXyl1 Modulates Plant Immunity

Abstract

<i>Botrytis cinerea</i> is one of the most notorious pathogenic species that causes serious plant diseases and substantial losses in agriculture throughout the world. We identified BcXyl1 from <i>B. cinerea</i> that exhibited xylanase activity. Expression of the <i>BcXyl1</i> gene was strongly induced in <i>B. cinerea</i> infecting <i>Nicotiana benthamiana</i> and tomato plants, and <i>BcXyl1</i> deletion strains severely compromised the virulence of <i>B. cinerea</i>. BcXyl1 induced strong cell death in several plants, and cell death activity of BcXyl1 was independent of its xylanase activity. Purified BcXyl1 triggered typically PAMP-triggered immunity (PTI) responses and conferred resistance to <i>B. cinerea</i> and TMV in tobacco and tomato plants. A 26-amino acid peptide of BcXyl1 was sufficient for elicitor function. Furthermore, the BcXyl1 death-inducing signal was mediated by the plant LRR receptor-like kinases (RLKs) BAK1 and SOBIR1. Our data suggested that BcXyl1 contributed to <i>B. cinerea</i> virulence and induced plant defense responses.