The induction of tomato leucine aminopeptidase genes (LapA) after Pseudomonas syringae pv. tomato infection is primarily a wound response triggered by coronatine

Tomato plants constitutively express a neutral leucine aminopeptidase (LAP- N) and an acidic LAP (LAP-A) during floral development and in leaves in res ponse to insect infestation, wounding, and Pseudomonas syringae pv, tomato infection. To assess the physiological roles of LAP-A, a LapA-antisense con struct (35S:asLapA1) was introduced into tomato. The 35S:asLapA1 plants had greatly reduced or showed undetectable levels of LAP-A and LAP-N proteins in healthy and wounded leaves and during floral development. Despite the lo ss of these aminopeptidases, no global changes in protein profiles were not ed. The 35S:asLapA1 plants also exhibited no significant alteration in flor al development and did not impact the growth and development of Manduca sex ta and P. syringae pv. tomato growth rates during compatible or incompatibl e infections. To investigate the mechanism underlying the strong induction of LapA upon P. syringae pv. tomato infection, LapA expression was monitore d after infection with coronatine-producing and -deficient P. syringae pv, tomato strains. LapA RNA and activity were detected only with the coronatin e-producing P. syringae pv, tomato strain. Coronatine treatment of excised shoots caused increases in RNAs for jasmonic acid (JA)-regulated wound-resp onse genes (LapA and pin2) but did not influence expression of a JA-regulat ed pathogenesis-related protein gene (PR-1). These results indicated that c oronatine mimicked the wound response but was insufficient to activate JA-r egulated PR genes.