A thaumatin-like gene from Asparagus officinalis (AoPRT-L) exhibits slow activation following tissue maceration or salicylic acid treatment, suggesting convergent defence-related signalling in monocots.

Summary Messenger RNA derived from mechanically separated cells of asparagus has proved to be an enriched source of defence-related transcripts. We describe the characterization of a novel PR-5 gene coding for a secreted protein of neutral pI (AoPRT-L) that is strongly up-regulated following cell isolation or following accelerated tissue ageing caused by tissue maceration, but which is also responsive to salicylic acid, a defence-related signal not normally associated with wound responses. Infection with the necrotizing fungal pathogen Stemphylium vesicarium confirmed the responsiveness of AoPRT-L to pathogen challenge in intact plants. An upstream region of the AoPRT-L gene of less than 500 bp was sufficient to confer SA-inducibility in transgenic tobacco. The expression profile of AoPRT-L in both macerated and pathogen challenged tissue suggested there were complex, convergent signalling mechanisms operating during responses to these different stresses.