STRESS METABOLITE PRODUCTION IN POTATO-TUBERS INFECTED BY PHYTOPHTHORA-INFESTANS, FUSARIUM-AVENACEUM AND PHOMA-EXIGUA

The stress metabolites rishitin, phytuberin, desacetylphytuberin and solavetivone were found in 8 different cultivars of potato tuber inoculated with P. infestans, Fusarium avenaceum and P. exigua var. foveata. Concentrations of up to 83 .mu.g rishitin, 409 .mu.g phytuberin, 545 .mu.g desacetylphytuberin and 333 .mu.g solavetivone/g dry weight of infected tissue were found, although not all compounds were detectable in each interaction. Extracts from infected tissue were treated with diazomethane prior to mini-column chromatography which removed interfering apolar compounds including fatty acid methyl esters. Eluates were subjected to analytical gas chromatography on a 10% OV210 column which enabled simultaneous measurement of all 4 compounds due to a greatly improved resolution compared to the published gas chromatographic procedure for potato stress metabolites. Anhydro-.beta.-rotunol and lubimin, if present in the extracts, could also be quantitatively measured.