Figure 7
Rhizosphere colonization of A. brasilense Sp245, the 12-A mutant, the C-40A control mutant and the C-56A complemented mutant and visualization of tagged colonizing bacteria by CLSM. (a) The plants were grown in glass tubes with Hoagland hydroponic solution and examined at 7 days postinoculation with 5 × 106–107 CFU/mL of A. brasilense Sp245 (pMP2449-5), A. brasilense 12-A (pMP2449-5), A.brasilense C-40A (pMP2449-5) and A. brasilense C-56A (pMP2449-5) (the WT, mutant, and complemented mutant strains, respectively). Subsequently, the cells showing mCherry fluorescence were visualized using CLSM with an excitation wavelength of 561 nm, with fluorescence emission captured between 585 and 615 nm. Thereafter, the images were edited using the standard NIS elements in Nikon software. The bar corresponds to 10 µm. (b) The bacterial colonies recovered from the rhizosphere 1 week after inoculation under sterile soil conditions were tested for antibiotic resistance to distinguish the control and mutant strains and were counted. CFU/mL per gram of plant root values are presented on a logarithmic scale. Each experiment was repeated three times with five plants per experiment. Asterisks represent the statistical significance of the data (P < 0.05) according to Student’s t-test by SigmaPlot (Systat Software, San Jose, CA).
