AUTHOR=Cui Xinyue , Li Xinke , Li Shen , Huang Yan , Liu Na , Lian Sen , Li Baohua , Wang Caixia 

TITLE=Xylanase VmXyl2 is involved in the pathogenicity of Valsa mali by regulating xylanase activity and inducing cell necrosis

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1342714

DOI=10.3389/fpls.2024.1342714

ISSN=1664-462X

ABSTRACT=<p>Xylanase plays a key role in degrading plant cell wall during pathogenic fungi infection. Here, we identified a xylanase gene, <italic>VmXyl2</italic> from the transcriptome of <italic>Valsa mali</italic> and examined its function. <italic>VmXyl2</italic> has highly elevated transcript levels during the infection process of <italic>V. mali</italic>, with 15.02-fold increase. Deletion mutants of the gene were generated to investigate the necessity of <italic>VmXyl2</italic> in the development and pathogenicity of <italic>V. mali</italic>. The <italic>VmXyl2</italic> deletion mutant considerably reduced the virulence of <italic>V. mali</italic> 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 <italic>V. mali</italic> 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 <italic>in vivo</italic>, a receptor-like kinase with leucine-rich repeat. The results offer valuable insights into the roles of VmXyl2 in the pathogenicity of <italic>V. mali</italic> during its infection of apple trees.</p>