Involved in defense against pathogens. May contribute to disease resistance by potentiating disease resistance signaling, or producing phytoalexin-like secondary products. Highly expressed in young panicles. Expressed in leaf sheaths and panicles. The gain-of-function mutants Spl18 (T-DNA tagging) show a lesion mimic phenotype, express constitutively PBZ1, accumulate the phytoalexins momilactone A and sakuranetin, and display enhanced resistance to rice blast fungus (M.oryzae). Plants over-expressing SPL18 show a lesion mimic phenotype and display enhanced resistance to bacterial blight (X. oryzae pv. oryzae). Belongs to the plant acyltransferase family.