Geographical variation of solanidane aglycone glycoalkaloids in the wild potato species Solanum chacoense Bitter

The Colorado Potato Beetle is a serious pest of the cultivated potato. Natu ral resistance has been found in a few wild species, including Solanum chac oense Bitter, in which the resistance is attributed to the presence of lept ine glycoalkaloids. Production and accumulation of these compounds within S . chacoense varies widely and appears to be inherited in a quantitative fas hion, but high leptine-producing clones occur rarely. In the present study, 15 different accessions from various locations and altitudes of origin wit hin central to northern Argentina and Paraguay were analyzed for foliar gly coalkaloid (leptine, leptinine, solanine, chaconine) content. The objective was to infer the frequency of leptine production in ecogeographically dist inct S. chacoense accessions, and to ascertain any possible association bet ween leptine levels/concentrations and ecogeographical location. Leptines w ere detected in 8 of the 15 accessions, and the amounts within each accessi on varied widely. Most of the leptine-containing accessions originated from western Argentina except two in province Cordoba in central Argentina. The re was no relationship between elevational level and leptine, but there was a negative trend with total glycoalkaloids (TGA) and elevation, due to sol anine and chaconine levels which decreased with increasing elevation. In ad dition, nine unidentified, putative glycoalkaloids were detected, in very h igh proportions in some individuals and accessions. This study raises inter esting questions about glycoalkaloid distribution, helps provide direction for new avenues of leptine and glycoalkaloid research, and proposes a syste matic, ecogeographically based method for bioprospecting genes controlling rare plant secondary compounds.