Occurrence of sapogenins in leaves and seeds of quinoa (Chenopodium quinoaWilld)

Seeds of the Andean seed crop quinoa usually contain saponins in the seed c oat. Saponins give a bitter taste sensation and are a serious antinutrition al factor. Therefore selection of sweet genotypes with a very low saponin c ontent in the seeds is a main breeding goal. However, selection for sweet g enotypes is retarded by cross-pollination. Early identification of sweet an d bitter quinoa genotypes before anthesis would speed up breeding considera bly. The ability to distinguish sweet and bitter genotypes was investigated in a glasshouse and in a field experiment. In the glasshouse experiment th e content of sapogenins was determined in leaves of sweet and bitter quinoa genotypes at successive stages of plant development and finally in the see ds. Detectable amounts of sapogenins were found earliest 82 days after sowi ng in leaves of both sweet and bitter quinoa genotypes. The total sapogenin content in leaves of sweet and bitter genotypes increased during plant dev elopment but remained lower than the content found in the seeds. The sapoge nin content in seeds of sweet genotypes varied from 0.2 to 0.4 g kg(-1) dry matter and in seeds of bitter genotypes from 4.7 to 11.3 g kg(-1) dry matt er. The difference in sapogenin content between leaves and seeds was much h igher in bitter genotypes than in sweet genotypes. Hederagenin was the majo r sapogenin found in leaves, and oleanolic acid in seeds. In the field expe riment it was found that the content of sapogenins in the leaves of F2 plan ts of crosses between both quinoa types did not differ between sweet and bi tter genotypes. The obtained results demonstrated that sweet genotypes coul d not be selected before anthesis on the basis of the sapogenin content in the leaves. (C) 2000 Society of Chemical Industry.