Glycoalkaloid content in Solanum species and hybrids from a breeding program for resistance to late blight (Phytophthora infestans)

As part of an effort; to study the relationship between the "glycoalkaloid trait" and genetic resistance to late blight (Phytophthora infestans), glyc oalkaloid content in tuber and foliar tissues from a wide genetic backgroun d within Solanum, including S. demissum, S, iopetalum and 15 hybrids select ed hom a backcrossing breeding scheme was determined. Analysis of variance indicated significant genotypic effect on total glycoalkaloid, solanidine, alpha -solanine, and alpha -chaconine content in both tubers and leaves. Tu bers from wild potato species commonly contain glycoalkaloids in concentrat ions that exceed international health regulations for human consumption (20 mg/100 g fresh weight), In this study, S, demissum and S, iopetalum were h ighest in total tuber glycoalkaloids among all materials tested, with 70.4 and 76.2 mg/100 g fresh weight, respectively. In contrast, both commercial cultivars had the lowest concentration, both below the safety Limit, Solani ne was more abundant than chaconine in all but one genotype. All hybrids we re intermediate to low in total glycoalkaloids, Except for the two wild spe cies, glycoalkaloid concentration in leaves of all genotypes studied was at lease twice that in tubers, with glycosylated forms accounting for more th an 80% total glycoalkaloid content. Correlation between tuber and foliage a lkaloids was poor. In view of the observed field resistance to late blight, it wits concluded that tuber glycoalkaloid content may not be responsible for such resistance.