Phytotoxins from Fungi of Esca of Grapevine

Abstract

The chemical composition of the culture media of five fungi involved in esca of grapevine have been investigated. Eutypa lata, extensively studied some years ago, produces eutypine [4-hydroxy-3-(3-methyl-3-butene- 1-ynyl)benzaldehyde] that seems to be the most phytotoxic metabolite. Using the same analytical method for Stereum hirsutum, we isolated nine compounds. Sterehirsutinal, a compound similar to frustulosine, but having two vinylacetylenic chains, possesses a toxicity comparable to eutypine. From Phaeoacremonium chlamydosporum we isolated nine metabolites that have not been extensively tested, but the simplest one, p-hydoxybenzaldehyde, shows marked toxicity. Other compounds (naphthalenone derivatives) are known to be involved in different wood diseases. From Phaeoacremonium aleophilum we also isolated p-hydroxybenzaldehyde and scytalone. Preliminary results on Fomitiporia punctata confirmed again the presence in the culture medium of p-hydroxybenzaldehyde and of a new chromanone biogenetically related to eutypine. The presence of molecules carrying the aldehyde function seems to play an important role in the toxicity of the five fungi implicated in esca.