Heterogeneity of Tomato Metabolites induced by Ralstonia solanacearum with Varied Pathogenicity

Gas chromatography-mass spectrometry was employed for the investigation on the heterogeneity of metabolites in tomato plants infected by strains of Ralstonia solanacearum with varied pathogenicity. The plants were inoculated with the virulent FJAT-91 and/or avirulent FJAT-1458, as well as water as control. After 6, 24, 48, 72 and 96 h, metabolites in the plants were analyzed. The results showed the metabolites were mostly alcohols, esters, acids, aldehydes, pyridines, and alkanes. The compositional differences on the plants infected by different pathogenic strains were compared. It was found that the number of metabolite varieties in the plants varied by the treatments and time. The tomato plants treated by FJAT-91 for 48 h had 12 different metabolites; those treated by FJAT-1458 for 48 h, 18;those treated by both strains simultaneously for 96 h, 15;and, control treated for 72 or 96 h, 15. Dibutyl phthalate was the only metabolite present in all samples. n-hexadecanoic acid was absent in the plants inoculated with FJAT-91, but was detected at considerable amounts in those infected with FJAT-1458 or combined strains, and control. The discrepancy might be due to a variation in the immunology of the tomato plants. A principal component analysis on the metabolites revealed discernible differences among the tomato plants that received different treatments. It suggested that the viral infections could be identified by comparing the two most abundant metabolites in a plant.