Glycoalkaloids in potato tubers: the effect of variety and drought stress on the alpha-solanine and alpha-chaconine contents of potatoes

Six varieties of Solanum tuberosum L potato grown in the Bolivian highlands under drought stress, with and without irrigation, were analysed for their content of glycoalkaloids (GAs). The plant material consisted of three drought-tolerant varieties from a local breeding progranune (PROINPA), Potosina, Chapaquita and Pampena, and three control cultivated varieties, Malcacho, Sani Imilla and Desiree, either susceptible or relatively tolerant to drought, alpha -Solanine and alpha -chaconine were quantified in both the peel and flesh of the tubers. A significant increase in GA concentration (alpha -solanine+alpha -chaconine) was observed under drought stress conditions in most varieties; average concentration increases of 43 and 50% were registered in the improved and control cultivars respectively. In all tested cultivars, however, the GA concentration remained lower than the recommended food safety level (200 mg kg(-1) fresh tubers). It ranged from 52.4 to 100 mg kg(-1) fresh tubers in the improved cultivars and from 55.6 to 122.3 mg kg(-1) fresh tubers in the controls. In the improved and control varieties the cu-solanine content averaged 42.6 and 35.4% of the total potato GAs respectively and was not significantly affected by drought stress, except in Desiree. In all conditions the peel contained the greatest proportion of total GAs. The hybrid variety Pampeiia (new drought-tolerant variety) contained the lowest amounts of GAs, which were lower than those of the control varieties, with and without irrigation. (C) 2000 Society of Chemical Industry.