Computational proteomics analysis reveals pathogen secreted carbohydrate active enzymes in tomato xylem sap

Abstract Fusarium oxysporum f. sp. lycopersici (Fol), a causal organism of Fusarium wilt in the tomato plant, secretes cell wall degrading enzymes, also known as carbohydrate-active enzymes (CAZymes). These are crucial during colonization and pathogenesis, as evidenced by several proteomic studies, revealing the importance of these CAZymes in virulence and pathogenicity. However, few of them have been done in-planta, exhibiting differences in the expression of these cell wall degrading enzymes compared to in-vitro studies. Therefore, to explore the CAZymes involved in pathogenesis while residing in the host plant, an in-planta (xylem sap) proteomics of a susceptible tomato variety affected with Fol was done. Most of these CAZymes belonged to the hydrolase and oxidoreductase families having no significant homology with tomato proteins. Nearly 90% of them were predicted to be soluble and extracellular. The core CAZymes families with interactional evidence identified were AA3, GH3, GH18, GH20, GH28, GH43, GH47, GH55 and CE8. Thus, apart from annotating some of the hypothetical proteins to be CAZymes, the study sheds light on CAZymes families that may have a role in the pathogenesis and survival of this fungus in the susceptible tomato plant.