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.