EVALUATION OF WILD TUBER-BEARING SOLANUM ACCESSIONS FOR FOLIAR GLYCOALKALOID LEVEL AND COMPOSITION

Six hundred forty-five accessions of 70 Solanum species and six natural hybrids were, screened for foliar glycoalkaloids. Total foliar glycoalkaloid (TFGA) level and glycoalkaloid composition of one or more accessions each species were determined by TLC and GLC analyses. Of the more than 12 different glycoalkaloids found in the wild species in this survey, solanine and chaconine account for more than 60% of the TFGA found in the foliage of these plants. There was wide variation in the total glycoalkaloid levels among the species. S. neocardenasii had the highest average TFGA value of the 70 species, 222 mg/100 g fresh wt (222 mg %) and an accession of S. chaocoense had the highest TFGA value recorded in the survey, 486 mg %. Of the 70 species, only 11 had average TFGA levels of more than 100 mg %. However, one or more accessions in 27 of the species synthesized more than 100 mg %. Forty-five species synthesized an average level of less than 50 mg %. The level usually found in the foliage of commercial potato cultivars is about 50 mg %. Therefore, most of the Solanum species in the potato germplasm collection can be considered low glycoalkaloid species.