TABLE 6.
Population densities of P. fluorescens Q8r1-96Gm and complemented mutants on the roots of wheat grown in Quincy virgin soila
| Expt | Strain | Population densities (AUCPC)b
|
||
|---|---|---|---|---|
| Q8r1-96Gm(pME6010) | Complemented mutant | Q8r1-96Gm(pME6010) and mutant (1:1) | ||
| 1 | Q8r1-96Gm(pME6010) | 7.6 a (43.7 abc) | ND | 7.5 a (40.0 cc) |
| Q8r1-96sss(pME6010sss) | ND | 7.6 a (44.6 ac) | 7.8 a (40.5 bcc) | |
| 2 | Q8r1-96Gm(pME6010) | 7.6 a (44.2 ab) | ND | 7.4 a (43.2 b) |
| Q8r1-96orfT(pME6010orfT) | ND | 7.7 a (44.8a) | 7.4 a (42.8 b) | |
| 3 | Q8r1-96Gm(pME6010) | 7.6 a (43.8 ab) | ND | 7.4 a (43.0 b) |
| Q8r1-96ptsP(pME6010ptsP) | ND | 7.7 a (45.1 a) | 7.4 a (41.0 c) | |
Raw Quincy virgin soil was treated with ∼104CFU g−1 soil of Q8r1-96Gm(pME6010) and/or Q8r1-96sss(pME6010sss), Q8r1-96orfT(pME6010orfT), or Q8r1-96ptsP(pME6010ptsP). Mixed-inoculation treatments contained a 1:1 mixture of competing strains (∼0.5×104 CFU g−1 soil of each strain). Rhizosphere population densities of bacteria were determined by the terminal dilution endpoint assay described in Materials and Methods.
The values are mean population densities in log CFU per g (fresh weight) of root for six cycles except cycle 0. Mean population densities in each experiment were analyzed separately. The values in parentheses are areas under the rhizosphere colonization progress curves (AUCPC) for introduced bacteria for six cycles. Different letters after values indicate that there is a statistically significant difference as determined by Fisher's protected least-significant-difference test (P = 0.05) (unless indicated otherwise). ND, not detected.
The significance of differences between AUCPC was determined by the Kruskal-Wallis all-pairwise comparison test (P = 0.05).