Global characterization of GH11 family xylanases genes in and functional analysis of and .

Rhombic-spot disease, caused mainly by , significantly impacts the yield and quality of fishscale bamboo (). Xylanases are essential for pathogenic fungi infection, yet their specific functions in the physiology and pathogenicity of remain unclear. Here, we characterized three xylanase proteins with glycosyl hydrolase 11 domains from the SICAUCC 16-0001 genome and examined the function of Nsxyn1 and Nsxyn2. Purified Nsxyn1 and Nsxyn2 proteins displayed specific xylanase activity and induced cell death in , independent of their enzymatic function. Both proteins possessed signal peptides and were confirmed as secreted proteins using a yeast secretion system. Subcellular localization revealed that Nsxyn1 and Nsxyn2 localized in both the cytoplasm and nucleus and can trigger cell death in through -mediated transient transformation. qRT-PCR results showed notable upregulation of and during infection, with exhibiting an 80-fold increase at 15 days post-inoculation. Deletion of and in impaired xylan degradation, adaptation to osmotic and oxidative stress, and pathogenic full virulence. Deletion of notably slowed fungal growth and reduced spore production, whereas only a reduction in microconidial production was observed in mutants. Complementation of and only partially restored these phenotypic defects in the ∆ and ∆ mutants. These findings suggest that Nsxyn1 and Nsxyn2 contribute to virulence and induced plant defense responses, providing new insights into the function of xylanases in the interaction between fishscale bamboo and .