ACCUMULATION OF THE CHALCONE ISOSALIPURPOSIDE IN PRIMARY LEAVES OF BARLEY FLAVONOID MUTANTS INDICATES A DEFECTIVE CHALCONE ISOMERASE

Mutants defective in flavonoid biosynthesis have become increasingly u seful in elucidating the potential functions of these compounds in pla nts. To define the role of flavonoids as UV-B protectants in barley, w e have screened part of the collection of proanthocyanidin-free barley mutants at the Carlsberg Research Laboratory, Copenhagen, Denmark. Th e four mutants ant 30-245, ant 30-272, ant 30-287 and ant 30-310 showe d drastically reduced flavonoid levels in the primary leaf as compared to their corresponding parent varieties, and in addition accumulated a new mutant-specific phenolic compound which was identified as the ch alcone glucoside isosalipurposide. Results from diallelic crosses indi cate that all four mutants belong to the same new complementation grou p, which is designated as the Ant 30 locus. This gene has not earlier been described in barley. The data presented suggest a defective chalc one isomerase gene for the observed flavonoid pattern in leaves of ant 30 mutants.