EFFECT OF BRUISING ON THE TOTAL GLYCOALKALOID AND CHLOROGENIC ACID CONTENT OF POTATO (SOLANUM-TUBEROSUM) TUBERS OF 5 CULTIVARS

Tubers from five potato cultivars were selected on the basis of their low, intermediate or high rates of glycoalkaloid synthesis in response to stresses such as light or cold storage temperatures. The tubers we re subjected to a standard degree of damage sufficient to cause bruisi ng but not severe damage such as cracking or splitting. Increases in g lycoalkaloid levels in response to damage were observed in all cultiva rs. Importantly, the rates of glycoalkaloid synthesis in response to d amage were in good agreement with cultivar response to light and cold temperature stress. The cultivars, Ailsa and Eden, exhibited a slower response than the higher synthesis rates observed in Pentland Dell or Brodick. The cultivar Torridon exhibited severe internal damage sympto ms throughout the tuber as opposed to localised bruising observed in t he other cultivars. The extensive cell death observed in the tubers of the cultivar Torridon severely curtailed glycoalkaloid and chlorogeni c acid synthesis. The increased levels of glycoalkaloids in response t o bruising damage ranged from approximately 27% (Ailsa, Torridon) to 1 30% for the cultivar Brodick. Chlorogenic acid levels increased in two cultivars (Brodick and Torridon) but not in the others, Ailsa, Eden a nd Pentland Dell. The alpha-chaconine/alpha-solanine ratios observed w ithin the five cultivars were in good agreement with previous research . The consistency across years is notable, indicating a strong relatio nship in the synthesis of the two glycoalkaloids. The results are disc ussed in terms of implications for the potato industry, for the retail trade and also for selection within potato breeding programmes. (C) 1 998 SCI.