The developmental expression of the asparagus intracellular PR protein (AoPR1) gene correlates with sites of phenylpropanoid biosynthesis

Abstract

Previous reports have described the induction, by either wounding or attempted pathogen invasion, of an Asparagus officinalis intracellular pathogenesis-related (AoPR1) promoter-GUS gene fusion in transgenic tobacco. Here we describe the unexpected developmental expression pattern of the AoPR1-GUS gene which correlates well, temporally and spatially, with the developmental expression observed for GUS fusions with promoters derived from genes coding for enzymes in the 'core phenylpropanoid pathway'. Analysis of endogenous AoPR1 gene expression in asparagus and both AoPR1-GUS and AoPR1-luciferase gene fusions in transgenic tobacco suggests that the AoPR1 promoter directs similar cell-specific transcription patterns in both asparagus and transgenic tobacco. The AoPR1 promoter contains sequence motifs similar to those implicated as important in the regulation of phenylpropanoid pathway genes and another 'intracellular' PR gene. Treatment with salicylic acid enhances AoPR1 promoter gene activity both in tobacco and in asparagus.