Table 1.
Characteristics of the symbiotic interaction between different NF-independent Aeschynomene species and the WT and ΔnifV mutant of Bradyrhizobium ORS285.
| Plant species | Growth stimulation plants | Mean number of nodules/plant | Legheamoglobin degradation (green nodules) | Nitrogenase enzyme activity (nmol ethylene/hr/plant) | “Ethane formation” | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| WT | ΔnifV | WT | ΔnifV | WT | ΔnifV | WT | ΔnifV | WT | ΔnifV | |
| A. evenia | +++ | − | 17 ± 1 (A) | 28 ± 1 (B) | no | yes | 370 ± 28 (A) | 27 ± 7 (B) | no | yes |
| A. indica | +++ | − | 33 ± 2 (A) | 49 ± 3 (B) | no | yes | 590 ± 26 (A) | 340 ± 120 (B) | no | yes |
| A. scabra | +++ | − | 17 ± 1 (A) | 33 ± 1 (B) | no | yes | 534 ± 89 (A) | 190 ± 17 (B) | no | yes |
| A. sensitiva | +++ | − | 14 ± 3 (A) | 27 ± 3 (B) | no | yes | 332 ± 34 (A) | 69 ± 24 (B) | no | yes |
| A. deamii | +++ | − | 24 ± 1 (A) | 45 ± 2 (B) | no | yes | 665 ± 59 (A) | 31 ± 10 (B) | no | yes |
| A. denticulata | +++ | − | 18 ± 1 (A) | 48 ± 2 (B) | no | yes | 402 ± 29 (A) | 227 ± 30 (B) | no | yes |
| A. virginica | +++ | + | 39 ± 2 (A) | 82 ± 3(B) | no | yes | 867 ± 89 (A) | 819 ± 35 (A) | no | yes |
| A. tambacoudensis | ++ | − | 25 ± 3 (A) | 49 ± 1(B) | no | yes | 247 ± 13 (A) | 80 ± 13 (B) | no | yes |
| A. pratensis | +++ | + | 11 ± 1 (A) | 23 ± 1 (B) | no | yes | 202 ± 62 (A) | 151 ± 12 (A) | no | yes |
| A. selloi | +++ | + | 20 ± 2 (A) | 29 ± 1 (B) | no | yes | 574 ± 55 (A) | 482 ± 34 (A) | no | yes |
Seeds of different Aeschynomene species were sterilized, germinated and seedlings were inoculated with Bradyrhizobium ORS285 and Bradyrhizobium ORS285 ΔnifV, respectively. At 22 (A. evenia) or 28 dpi (others), the plant growth was compared with non–inoculated control plants and the mean nodule number, mature nodule phenotype and mean nitrogenase enzyme activity as analysed by the ARA assay was determined. +++: no N-starvation signs and plants are much better developed than the non-inoculated control plants; ++: no N-starvation signs and plants are better developed than the non-inoculated control plants; +: plants are better developed than the non-inoculated control plants but have signs of foliar chlorosis; −: no difference with non-inoculated control plants. ±Indicates the standard error of the mean. Letters in brackets in the table represent conditions with significant difference according to the Tukey’s test (P < 0.05).