Local and systemic induction of two defense-related subtilisin-like protease promoters in transgenic Arabidopsis plants. Luciferin induction of PR gene expression

Following a pathogenic attack, plants are able to mount a defense response with the coordinated activation of a battery of defense-related genes. In t his study we have characterized the mode of expression of the P69B and P69C genes from tomato (Lycopersicon esculentum Mill.), which encodes two close ly related subtilisin-like proteases associated with the defense response. We have compared the mode of gene regulation in heterologous transgenic Ara bidopsis plants harboring promoter-P-glucuronidase (GUS) and promoter-lucif erase (LUC) gene fusions for these two genes. These studies revealed that t he P69B and P69C promoters are induced by salicylic acid as well as during the course of both a compatible and an incompatible interaction with Pseudo monas syringae. Furthermore, P69B and P69C expression takes place in both t he local and the distal (noninoculated) leaves upon inoculation with bacter ia but following different and unique tissue-specific patterns of expressio n that are also different to that described for most other classical PX gen es. Also, we report that luciferin, the substrate for the reporter lucifera se (LUC) gene, is able to activate expression of PR genes, and this may pos e a problem when using this gene reporter system in studies related to plan t defense.