Defense gene expression patterns of three SAR-induced tomato cultivars in the field

Plant activation is an appealing disease management tool, avoiding some of the challenges of traditional chemical control by not directly impacting the pathogen. This study examined effects of acibenzolar-S-methyl (ASM), a plant activator that induces systemic acquired resistance, on defense response activation in three field-grown tomato cultivars in New York. Salicylic acid, ethylene and jasmonic acid-mediated responses were monitored by following expression of a marker gene for each signaling pathway using quantitative real-time PCR over the course of two ASM applications. ASM induced salicylic acid and ethylene, but not jasmonic acid-regulated gene expression in all cultivars tested. All three cultivars demonstrated a significantly stronger gene expression response relative to the untreated control following the second ASM application. Implications of these findings on management practices are discussed.