The role of a Strictosidine synthase-like gene-6 in Arabidopsis thaliana defense against Alternaria brassicicola

Strictosidine synthase is a key enzyme in the biosynthesis of plant alkaloids. The homologous of the strictosidine synthase domain has been found in different organisms such as Arabidopsis thaliana. Bioinformatics and expression studies on one of the strictosidine synthase-like gene (SSL6) in Arabidopsis plants showed that gene responded to the signaling molecules, fungal and viral pathogens. The functional role of SSL6 has been further studied using an Arabidopsis knockout mutant with a T-DNA inserted into exon 1. The plants were inoculated with Alternaria brassicicola, which had incompatible interaction with A. thaliana. The fungal biomass was quantified by quantitative real-time PCR and spore count techniques. The assays indicated that T-DNA mediated ssl6 mutant was more susceptible than Col-0 genotype. The chlorophyll content and the size of necrotic lesions were significantly smaller in the ssl6 mutant compared with the Col-0. This is the first report with reference to the functional analysis of SSL6 suggesting that might be SSL6 plays an important role, among other factors, in plant defense against A. brassicicola.