Distribution of GA20-13-O-glucoside and reconversion of [17-D2]GA20-13-O-glucoside in caryopses of Hordeum vulgare L. cv. Himalaya.

摘要

The distribution of GA20 and GA20-13-O-glucoside was examined in mature caryopses of barley (Hordeum vulgare) cv. Himalaya. It was shown by GC-MS that GA20-13-O-glucoside is localized mainly in the embryo-containing part of the grain. In order to study the reconversion of GA20-13-O-glucoside during early germination, the glucoside pool of cv. Himalaya was [17-D2]-labelled by feeding [17-D2]GA20. The metabolites of [17-D2]GA20-13-O-glucoside were quantified by GC-MS during germination on the basis of doubly labelled standards. As soon as 6 h after incubation, an increase of [17-D2]GA20 could be observed, followed by an increase of [17-D2]GA1 after 12 h, showing that the enzymes of the late GA metabolism are present before de novo biosynthesis started.