Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2003
Publication Date: 9/3/2003
Citation: Mahoney, N.E., Lardner, R., Molyneux, R.J., Scott, E.S., Smith, L.R., Schoch, T.K. 2003. Phenolic metabolite profiles of the grapevine pathogen eutypa lata. Phytochemistry. 64(2):475-484. Interpretive Summary: Dying-arm disease in grapevines is caused by a fungus that enters the plant through pruning wounds and causes withering of new shoots and leaves. The fungus produces a number of toxic compounds when grown on artificial nutrients in the laboratory. This work has shown that much larger amounts of the compounds are produced when the fungus is grown on a hot water extract of grapevines. This will provide amounts suitable for testing the effect of the compounds on grapevine leaves.
Technical Abstract: The ascomycete Eutypa lata is the causative agent of eutypa dieback or "dying arm disease" in grapevines, a serious economic problem in major wine grape producing areas, including California and Australia. In order to develop a predictive, non-destructive assay for early detection of fungal infection, the phenolic metabolite profiles of 11 strains of E. lata, from representative locations of the world, were analyzed. The variability in these profiles with four different artificial growth media was investigated and compared with those of the same strains grown on Cabernet Sauvignon grapevine wood and wood extracts. Six compounds were generally produced in significant amounts, namely eutypinol (1), its chromene analog, eulatachromene (2), the corresponding aldehyde, eutypine (3) and its cyclization product, the benzofuran (4), together with the quinol, siccayne (5) and its methoxyquinol analog, eulatinol, (6). Metabolite production on grapevine extract was greatly enhanced relative to the artificial media, indicating that this native substrate provides optimal conditions and a more representative profile of the metabolites produced in the natural disease state. The primary metabolites were tested in a grapeleaf disc bioassay to establish their relative toxicity. The results indicate that eutypa dieback may be caused by several E. lata metabolites rather than a single compound and that analysis of grapevine tissues for the presence of eutypinol may be the best predictor of fungal infection.