Molecular Characterization of CYP73A9 andCYP82A1 P450 Genes Involved in Plant Defense in Pea

Abstract

Abstract Cytochrome P450 monooxygenases (P450s) mediate a wide range of oxidative reactions involved in the biosynthesis of phenylpropanoids, terpenes, and alkaloids. Two pea (Pisum sativum) P450 cDNAs (CYP73A9v1, encoding trans-cinnamic acid hydroxylase [t-CAH] in the core phenylpropanoid pathway, and CYP82A1v1, possibly encoding an activity in a late branch of the phenylpropanoid pathway) have previously been described. Of three CYP73A9 genes now isolated, theCYP73A9v1 gene is full-length with two introns at positions conserved in other t-CAH genes, and theCYP73A9v2 and CYP73A9v3 gene fragments are 5′-truncated and lack introns. The full-lengthCYP82A1v2 gene contains a single intron at an alternate position. Nucleotide searches of the CYP73A9v1 andCYP82A1v2 promoters have indicated that the regulatory sequences for these early and late phenylpropanoid transcripts are substantially different. The P-, L-, and H-boxes identified in white light-, ultraviolet light-, and elicitor-induced footprints in early phenylpropanoid promoters (phenylalanine ammonia lyase [PAL], 4-coumarate coenzyme A:ligase [4-CL], and chalcone synthase [CHS]) are conserved in the t-CAH promoter and are absent from the CYP82A1v2 promoter. Both promoters contain TCA motifs identified in stress-responsive promoters, box IV elements identified in elicitor-responsive PAL andCHS promoters, and spatially conserved wound-response elements potentially coordinating regulation of these wound-responsive promoters.