Expression Pattern and Gene Structure of Phenylalanine Ammonia-Lyase in Pharbitis nil

PAL

gene expression were examined in flower buds and irradiated hypocotyls in Pharbitis nil. PAL activity and transcript levels were correlated with the accumulation of anthocyanin. Both in flower buds and hypocotyls, transcript levels, PAL activity, and then the amount of anthocyanin, increased. The PAL transcript was abundant in flower buds for a few days before flower opening. But the increase in PAL transcript induced by irradiation was temporal in hypocotyls. Phytochrome was shown to be involved in inducing the accumulation of anthocyanin in hypocotyls. To examine the mechanism regulating the expression of the PAL gene, the gene was cloned and sequenced, and the promoter region was compared with that of other PALs. The gene had two exons separated by an intron of 989 bp with consensus sequences at the intron/exon border. The predicted primary structure of the PAL protein consists of 711 amino acids. The promoter region was AT-rich and there were sequences similar to box 1, box 2, an AT-1 binding site and a G box. The role of PAL in the accumulation of anthocyanin is discussed.