Figure 6. Plasmid pFiD188 with functional fasR and fas is sufficient to transition Rhodococcus isolates to phytopathogens.

(A) Representative images of leafy galls on N. benthamiana. Red arrows indicate leafy galls. Images for GIC26, 04–516, and PBTS2 are repeated from Figure 1. (B) Representative images of the root lengths of seedlings. Three-day-old N. benthamiana seedlings were inoculated with the indicated isolate of Rhodococcus or water (mock) and grown vertically for seven days under constant light. (C) Quantification of the root lengths of N. benthamiana seedlings. In all panels, -/+ indicates absence or presence of pFiD188Δatt. * indicates a significant difference compared to plants treated with the corresponding genotype lacking the plasmid.

Figure 6—figure supplement 1. Rhodococcus isolate D188 with plasmid pFiD188Δatt is pathogenic.

(A) Representative images of leafy galls on N. benthamiana. Images were taken 56 days post inoculation (dpi). Red arrow indicates leafy gall. (B) Representative images of root length of seedlings. Three-day-old N. benthamiana seedlings were inoculated with the indicated isolate of Rhodococcus or water (mock) and grown vertically for seven days under constant light. (C) Quantification of root lengths of N. benthamiana seedlings. Data for D188 +pFiD188Δatt are the same as those shown in Figure 6.

Figure 6—figure supplement 2. Eviction of the virulence plasmid reverts isolate D188 to a beneficial bacterium.

(A) Rhodococcus D188ΔpFID188 causes changes in root architecture. White arrows indicate lateral roots and root hairs. The image was taken 42 days post inoculation (dpi); effects were seen earlier. (B) Rhodococcus D188ΔpFID188 is not pathogenic. The strain was inoculated onto N. benthamiana. The image was taken 56 dpi. (C) Rhodococcus isolate D188-5 is compromised in in vitro growth. Rhodococcus isolates D188, D188-5, and D188ΔpFiD188 were grown separately in LB media. Growth, determined using a Tecan plate reader, was quantified on the basis of OD₆₀₀ readings for a period of 16 hr. One representative experiment of three is shown; all had similar results. Error bars indicate SEM.

Figure 6—figure supplement 3. Rhodococcus isolate D188 carrying L5::attR is affected in virulence.

(A) Representative images of leafy galls on N. benthamiana. Images were taken 56 days post inoculation (dpi). Red arrows indicate a leafy gall. (B) Representative images of the root lengths of seedlings. Three-day-old N. benthamiana seedlings were inoculated with the indicated isolate of Rhodococcus or water (mock) and grown vertically for seven days under constant light. (C) Quantification of root lengths of N. benthamiana seedlings. * indicates a significant difference compared to treatment with D188.