Do Phaseolus vulgaris Development Stages Influence the Total Rhizospheric Bacterial and the Phytate Utilising Community?

Background: The occupation of soil by plants is known to induce changes in the soil chemical and physical properties by shoot decomposition and root growth and secretion. Methods: In this study we investigate the degree to which the total and the phytate mineralising rhizospheric communities bacteria are affected by the growth of six Recombinant Inbred Lines (RILs) of common bean (Phaseolus vulgaris). The six RILs tested were contrasted on adaptation to P (phosphorus)-deficiency from sensitive to tolerant. Rhizosphere samples were taken three times during the plant developmental stage and the changes in the density and the phytase activity of those communities relative to the P content were studied. Bacterial community was followed by culturing and measuring total community DNA of soil to allow a cultivation- independent analysis, by amplification of the 16S rRNA gene using real time PCR. Result: Our results showed that successional moves in the rhizosphere bacterial density as plant mature confirmed that plants select their own rhizosphere community. Moves of the bacterial community in the rhizosphere were more pronounced in mature common bean and phytase enzymatic activity confirmed the ability of this plant to mobilise a functional bacterial community when the bean needs high quantities of phosphorus. This study demonstrates that common bean selects a microbial community and its density change in response to plant growth.