CDNA CLONING AND GENE-EXPRESSION OF PHENYLALANINE AMMONIA-LYASE IN LITHOSPERMUM-ERYTHRORHIZON

Two cDNA clones (LEPAL-1 and LEPAL-2) encoding phenylalanine ammonia-l yase were isolated from cell suspension cultures of Lithospermum eryth rorhizon. Northern kinetic studies showed that LEPAL-1 mRNA contents m arkedly increased one day after inoculation of the cells into fresh me dium, then decreased to the steady-state level. The course of mRNA acc umulation paralleled that of PAL enzyme activity. The rapid induction of PAL activity seems to reflect the induction of dihydroechinofuran b iosynthesis, while shikonin was produced at the steady-state level of PAL activity. The course of LEPAL-2 mRNA accumulation seemed to be sim ilar to, but much lower than that of LEPAL-1. In the intact plant, bot h genes are expressed mainly in the root, the organ in which shikonin is exclusively produced and accumulated. Genomic Southern blot analyse s showed that both genes are present in the genome as single copies.