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Poster Session: Biology and Disease Management - Mycology

50-P

Wood-decay abilities of grapevine trunk pathogens Diaporthe ampelina, Diplodia seriata, Eutypa lata, and Neofusicoccum parvum.
E. GALARNEAU (1), C. Wallis (2), A. Morales-Cruz (3), D. Cantu (3), K. Baumgartner (4)
(1) USDA ARS CPGRU, Davis, CA, U.S.A.; (2) USDA ARS, Parlier, CA, U.S.A.; (3) University of California Davis, Davis, CA, U.S.A.; (4) USDA-Agricultural Research Service, Davis, CA, U.S.A.

Trunk pathogens are fungi that infect grapevine wood through pruning wounds and destroy fruiting positions, thereby impacting grape production. Neofusicoccum parvum (causal fungus of Botryosphaeria dieback) and Eutypa lata (causal fungus of Eutypa dieback) cause chronic infections (cankers) of the trunk/cordons, but vary in their utilization of woody substrate. We evaluated the wood-decay abilities of N. parvum (highly virulent), E. lata (known soft-rot fungus), Diplodia seriata (weakly virulent causal fungus of Botryosphaeria dieback), and Diaporthe ampelina (attacks both green and woody tissue, causal fungus of Phomopsis dieback/cane and leaf spot). The ability of these fungi to degrade cell wall components (e.g. phenolics, lignin, and cellulose) was evaluated by amending fungal cultures with these compounds and observing changes to compound levels over time using HPLC and colorimetric methods. Observed differences between these species on amended media were likely from differences in the preferred tissues each attacks. Findings were somewhat consistent with previous findings of similarities in the predicted secretomes of each fungus, which were seen between E. lata and N. parvum (e.g. enzymes that target cellulose and hemicellulose). Additional studies will examine levels of tested compounds in grapevine tissues surrounding wood lesions, in addition to fungal gene expression in-planta. Our findings may allow some of these fungi to be classified as soft-rot fungi.