Fig 1.
Scatter plot of log2 expression ratio for orthologous genes at 20°C compared to 28°C in planta.
The orthologs shared between UW551 and GMI1000 were divided into five groups based on expression pattern. Gray dots in the middle represent orthologs not differentially expressed by temperature in either strain; symbols in colors represent orthologs differentially expressed in at least one strain. Each symbol represents one ortholog.
Fig 2.
A cluster of genes adjacent to those encoding the SolI/R quorum sensing system were up-regulated in R. solanacearum strain UW551 at 20°C, in culture.
Some were also upregulated in planta. Arrows represent open reading frames. The numbers above the arrows indicate the expression fold-change for each gene at 20°C compared to 28°C, in culture/in planta, determined by whole-genome microarray analysis as described in the text. The arrangement and expression levels of the corresponding genes in strain GMI1000 are also shown.
Fig 3.
Mutation of R. solanacearum strain UW551 lecM, aidA, or aidC but not solI differentially reduced bacterial virulence at 20°C.
Virulence was measured on wilt-susceptible tomato plants at 20°C and 28°C via soil soak inoculation (A-E) or at 20°C via cut petiole inoculation (F). Each point represents the mean of three biological replicates, each containing 16 plants per strain per temperature. The area under disease progress curve (AUDPC) was measured for each strain in A-C and each mutant’s AUDPC relative to wild type is shown (E). Asterisks indicate that virulence of wild type and mutant strains were significantly different (* P< 0.05, ** P< 0.01, ANOVA). Each mutant was also significantly reduced in virulence (P< 0.01, repeated measures ANOVA) compared to the wild type following cut petiole inoculation (F).
Table 1.
Expression of lectin genes in R. solanacearum strains GMI1000 and UW551 under various conditions.
Fig 4.
UW551ΔlecM and UW551ΔaidC had reduced survival in potato tubers at 4°C.
Potato tubers were injected with different R. solanacearum strains, and bacterial cell numbers were counted by grinding and dilution plating tubers at different times after inoculation. The experiment was repeated three times, with three tubers per strain per time point. At 6, 9 and 12 weeks after inoculation, the population sizes of UW551ΔlecM and UW551ΔaidC in tubers were significantly lower than those of the wild type parent strain (P<0.05, ANOVA).