Pepper gene encoding a basic pathogenesis-related 1 protein is pathogen and ethylene inducible

A new basic pathogenesis-related (PR)-1 cDNA (CABPR1) was isolated from a cDNA library of pepper leaves infected with Xanthomonas campestris pv. vesicatoria. The full-length clone contains an open reading frame of 531 nucleotides encoding 177 amino acid residues with a predicted molecular mass of 20241 and pI of 8.1. The deduced amino acid sequence of CABPR1 has a high level of identity with PR-1 proteins from tobacco and tomato. Expression of the CABPR1 mRNA was greatly induced in an incompatible interaction of pepper leaves with X. campestris pv. vesicatoria. Accumulation of the basic PR-1 mRNA in the bacteria-infected leaves was intrinsically associated with the induction of ethylene biosynthesis. Treatment with 1-aminoethoxyvinylglycine, an inhibitor of ethylene biosynthesis, strongly suppressed the induction of PR-1 mRNA expression in the bacteria-infected leaves. These data suggest that ethylene mag function as a strong signal elicitor in the activation of PR-1 genes, eventually mediating the plant defence response. Phytophtora capsici infection also distinctly stimulated ethylene biosynthesis, together with accumulation of PR-1 mRNA, Expression of the basic PR-1 mRNA was also induced in the pepper leaves by treatment with DL-beta-amino-n-butyric acid or salicylic acid, but not by wounding. Treatment with methyl jasmonate, in combination with salicylic acid, strongly induced the PR-1 transcripts. The basic PR-1 gene expression occurred in untreated roots, flowers and green fruit of pepper but not in leaf, stem or red fruit.