Regulation of Anthocyanin Biosynthesis during Fruit Development in 'Nyoho' Strawberry.

Abstract

The expression of anthocyanin biosynthesis pathway genes was investigated in 'Nyoho' strawberry fruits during fruit development. Fruit color changed from pale-green to white about 3 weeks after anthesis (white-mature stage). At this stage, anthocyanins rapidly accumulated until the full ripe. Total soluble sugar content also increased after white-mature stage. This includes sucrose but not glucose and fructose levels that remained constant during ripening. The transcript level of phenylalanine ammonialyase (PAL) and chalcone synthase (CHS) genes did not change markedly throughout the fruit development. The transcript level of chalcone isomerase (CHI) and dihydroflavonol 4-reductase (DFR) gene was high in the young fruit, decreased to an almost undetectable level at the white-mature stage, and then increased again until the fully ripe stage paralleling mostly the accumulation of anthocyanin. The latter corelation suggests the involvement of CHI and DFR in the regulation of anthocyanin biosynthesis during fruit ripening.