Determination of Ascochyta caulina phytotoxins by high-performance anion exchange chromatography and pulsed amperometric detection

A simple and sensitive method has been developed for the rapid qualitative and quantitative analysis of the phytotoxins produced by Ascochyta caulina, a potential mycoherbicide for the biocontrol of Chenopodium album. Conside ring that the two main toxins produced by this fungus, namely ascaulitoxin and trans-4-amino-D-proline, and the third toxin, identified as 2,4,7-triam ino-5-hydroxyoctandioic acid, have an amino acid nature, high-performance a nion exchange chromatography with pulsed amperometric detection was the bes t method for their detection. The method was used to measure the toxin cont ent in the culture filtrates of different strains of A. caulina. The develo ped method could be employed as a tool to select more virulent strains by d etermining the higher toxin producers, if in vitro toxin accumulation was r elated to pathogen virulence. The chemical characterisation of the third to xin purified from A. caulina culture filtrates is also reported. Copyright (C) 2001 John Wiley & Sons, Ltd.