Table 3.
Pseudomonas fluorescens PICF7 root colonization ability and biocontrol performance of V. dahliae in different A. thaliana accessions.
| Experiment | A. thaliana genotype | Treatment | Disease assessment3 |
Bacterial population (log10 cfu g-1 of fresh root)4 |
|||
|---|---|---|---|---|---|---|---|
| SAUDPC | DII | Final DI % | PICF7 | Native | |||
| 1 | Col-0 | Control | 0.56a | 0.75 | 94.44 | na | 5.0d |
| P. fluorescens PICF7 | 0.25b | 0.51 | 76.47 | 6.6 ± 0.1ab | – | ||
| myb72 | Control | 0.49a | 0.74 | 77.78 | na | 5.7 ± 0.3c | |
| P. fluorescens PICF7 | 0.18bc | 0.33 | 44.44 | 6.3 ± 0.3b | – | ||
| sid2 | Control | 0.24b | 0.35 | 38.89 | na | 6.5 ± 0.4ab | |
| P. fluorescens PICF7 | 0.02c | 0.03 | 5.88 | 6.9 ± 0.3a | – | ||
| 2 | Col-0 | Control | 0.39abc | 0.55 | 80.00 | na | 3.7 ± 0.0b |
| P. fluorescens PICF7 | 0.33bc | 0.38 | 79.17 | 5.6 ± 0.2a | – | ||
| myb72 | Control | 0.54a | 0.74 | 92.00 | na | 2.8 ± 0.8c | |
| P. fluorescens PICF7 | 0.43ab | 0.56 | 72.00 | 5.3 ± 0.4a | – | ||
| sid2 | Control | 0.27c | 0.37 | 68.00 | na | 2.9 ± 0.2bc | |
| P. fluorescens PICF7 | 0.33bc | 0.47 | 72.00 | 5.5 ± 0.2 a | – | ||
| 3 | Col-0 | Control | 0.17b | 0.27 | 58.82 | na | 4.3 ± 0.1c |
| P. fluorescens PICF7 | 0.14b | 0.27 | 72.22 | 7.2 ± 0.4a | – | ||
| myb72 | Control | 0.14b | 0.29 | 55.00 | na | 5.9 ± 0.5b | |
| P. fluorescens PICF7 | 0.12b | 0.27 | 60.00 | 7.0 ± 0.4 a | – | ||
| sid2 | Control | 0.37a | 0.64 | 77.78 | na | 5.6 ± 0.4b | |
| P. fluorescens PICF7 | 0.22bc | 0.43 | 63.16 | 7.0 ± 0.1 a | – | ||
| 4 | Col-0 | Control | 0.12b | 0.22 | 47.37 | na | nd |
| P. fluorescens PICF7 | 0.12b | 0.19 | 23.81 | nd | nd | ||
| myb72 | Control | 0.27ab | 0.35 | 47.37 | na | nd | |
| P. fluorescens PICF7 | 0.14b | 0.23 | 40.00 | nd | nd | ||
| sid2 | Control | 0.39a | 0.55 | 70.00 | na | nd | |
| P. fluorescens PICF7 | 0.15b | 0.27 | 42.11 | nd | nd | ||
1Four independent experiments were conducted spanning 32 DAI (Experiment 1), 40 DAI (Experiments 2 and 3) or 37 DAI (Experiment 4).
2The root system of 2-week-old Arabidopsis seedlings were transplanted into PICF7-bacterized soil (8.0*107–2.8*108 cfu/g soil) previously autoclaved for colonization assays. In biocontrol experiments, 1 week after PICF7-treatment plants were uprooted and their root systems dipped in a V. dahliae isolate V937I (D pathotype) conidia suspension (3.9·105–4·106 conidia/ml) or distilled sterile water (control treatment) for 15 min. Plants were then grown in a growth chamber under controlled conditions. See Section “Materials and Methods” for details.
3Standardized area under the disease progress curve of DII plotted over time. Final DI, (percentage of affected plants at the end of the assay). Means in a column followed by different letters are significantly different in accordance to Fisher's protected LSD test (P < 0.05).
4Strain PICF7 and native bacteria cells counts were carried out on modified King’s medium B agar. Data are means of three root samples (1 g each). Means followed by different letters are significantly different in accordance to Two-sided Dunnett’s Multiple Comparisons with a Control (Col-0 plants) at α = 0.05. na, not applicable; nd, not determined in this experiment; –, native population not detected or negligible in PICF7-bacterized plants.