Abstract
The functional involvement of cyclic GMP (cGMP) in phytochrome-dependent producton of anthocyanin has been reported, whereas little is known about molecular mechanisms controlling gene expression by cGMP. Northern analyses using photomixotrophic soybean cell-culture (SB-P) revealed that gene expression of several flavonoid-biosynthetic enzymes was enhanced by cGMP. All cGMP-induced genes that we tested were also stimulated by nitric oxide (NO) and illuminaton of white light. Furthermore, we found that cGMP, NO, and white light could increase anthocyanin in SB-P cells suggesting that white light-dependent production of anthocyanin is mediated by cGMP and/or NO. On the other hand, promoter analyses of chalcone reductase gene indicated that the upper region of the promoter (-991 to -576 bp) was responsible for the induction by cGMP. We are now investigating the relation between the cGMP and/or NO signaling and phytochrome signal-transduction for gene regulation of flavonoid biosynthetic enzymes by pharmacological analysis.
