Phenylalanine ammonia-lyase genes from pisum sativum: Structure, organ-specific expression and regulation by fungal elicitor and suppressor

Genomic DNA clones representing two members of a small multigene family of phenylalanine ammonia-lyase (pal) in pea, designated PSPAL1 and PSPAL2, were obtained and the nucleotide sequences were determined. PSPAL1 and PSPAL2 each contain a single intron but the sizes of the introns are different. Using specific oligonucleotide probes from the 5'-noncoding region of PSPAL1 and PSPAL2, we showed that the accumulation of both PSPAL1 and PSPAL2 transcripts was induced in epicotyl tissues by treatment with the fungal elicitor isolated from a pea pathogen, Mycosphaerella pinodes, and transcripts of both PSPAL1 and PSPAL2 accumulated at high levels in roots and at moderate level in stems but at very low levels in the upper part of the plant that included leaves and flower organs. A chimeric gene carrying 480 bp of the putative promoter fragment of PSPAL1 connected to the bacterial cat gene and the nos terminator was introduced by electroporation into pea protoplasts and the induction by fungal elicitor and suppression by suppressor or orthovanadate, an inhibitor for plasma membrane ATPase, were examined by an transient assay for CAT activity. CAT activity was induced by the treatment with fungal elicitor but suppressed by the fungal suppressor and by orthovanadate.