Proteomic analysis reveals the potential involvement of xylanase from Pyrenophora teres f. teres in net form net blotch disease of barley

The barley pathogen Pyrenophora teres f. teres (Ptt) produces proteinaceous toxins that contribute to the necrotic symptoms observed during net form net blotch (NFNB) disease. To better understand the relationship between these toxins and virulence, a proteomics approach was used to identify proteins differentially expressed in a more virulent Ptt isolate. Three proteins were identified: an endo-1,4-beta-xylanase A (PttXyn11A), a cysteine hydrolase family protein (PttCHFP1) and an unknown (but conserved) secreted protein (PttSP1). PttXyn11A was homologous to a plant cell-wall degrading enzyme but also had a predicted necrosis-inducing region on the enzyme surface. PttCHFP1 showed homology to an isochorismatase, an enzyme proposed to suppress plant defence. Xylanase activity and PttXyn11A expression were greater in more virulent isolates in vitro and during the interaction respectively, suggesting that PttXyn11A plays a role in symptom development.