Abstract
To elucidate the molecular mechanisms of resistant response to Ralstonia solanacearum (Rs) on tomato, we inoculated Rs into the stems of resistant cultivar LS-89 and susceptible Ponderosa and performed comprehensive analyses of gene expressions at 24h post inoculation (hpi) using GeneChip. The expressions of about 150 genes were more than 2 hold up-regulated in LS-89 stems. Among these, the expressions of class III acidic and basic β-1,3-glucanase genes (glu) were substantially increased. Therefore, four glu (two Class III plus Class I and II) expressions were analyzed in detail using real-time PCR. The expressions of all glu in LS-89 were little changed at 12 hpi, induced by 24 hpi and further increased at 48 hpi. In Ponderosa, expressions of two glu were little changed and the others were induced only at 48 hpi. When two cultivars were inoculated with Rs at a concentration of 106 to 109 CFU/ml, we found that the relationships between the Rs concentrations and the gene expression levels were different among the four glu. These results suggest that all four glu are expressed against Rs infection in a concentration-dependent manner, but each gene is differently regulated.
