Xylanase VmXyl2 is involved in the pathogenicity of by regulating xylanase activity and inducing cell necrosis.

Xylanase plays a key role in degrading plant cell wall during pathogenic fungi infection. Here, we identified a xylanase gene, from the transcriptome of and examined its function. has highly elevated transcript levels during the infection process of , with 15.02-fold increase. Deletion mutants of the gene were generated to investigate the necessity of in the development and pathogenicity of . The deletion mutant considerably reduced the virulence of in apple leaves and in twigs, accompanied by 41.22% decrease in xylanase activity. In addition, we found that VmXyl2 induces plant cell necrosis regardless of its xylanase activity, whereas promoting the infection of in apple tissues. The cell death-inducing activity of VmXyl2 dependent on BRI1-associated kinase-1 (BAK1) but not Suppressor of BIR1-1 (SOBIR1). Furthermore, VmXyl2 interacts with Mp2 , a receptor-like kinase with leucine-rich repeat. The results offer valuable insights into the roles of VmXyl2 in the pathogenicity of during its infection of apple trees.