A 125 bp promoter fragment is sufficient for strong elicitor-mediated gene activation in parsley

We describe the nucleotide sequence and some structural characteristics of a single copy gene encoding pathogenesis-related protein 2 (PR2) in parsley (Petroselinum crispum). Transcriptional activation of this gene in cultured parsley cells treated with fungal elicitor leads to a rapid, large and transient accumulation of PR2 mRNA. The deduced PR2 protein belongs to a novel class of evolutionarily conserved polypeptides which are closely related to disease resistance in plants. Functional analysis of a series of truncated PR2 promoter fusions with the beta-glucuronidase reporter gene, using parsley protoplasts for transient expression studies, identified a 5' upstream element between positions -168 and -52 necessary for strong elicitor responsiveness. This small promoter fragment is active in conjunction with its own TATA box region as well as with the corresponding region from a heterologous promoter. The PR2 regulatory region exhibits no sequence similarity to any other elicitor-responsive promoter known to date.