Proton exudation mediated by GmVP2 showed comprehensive impacts on plant growth, P-remobilization and rhizosphere microbial community.

Increased root H + secretion is known as a strategy of plant adaption to low phosphorus (P) stress by enhancing mobilization of sparingly soluble P-sources. However, it remains fragmentary about the comprehensive effects induced by this enhanced rhizosphere acidification. The present study revealed that P deficiency increased the net H + flux rate from soybean (Glycine max) roots. Among the eight H  +-pyrophosphatases (GmVP) genes in soybean genome, GmVP2 showed the highest expression level under low P conditions. Transient expression of a GmVP2-GFP chimera in tobacco (Nicotiana tabacum) leaves, together with the functional characterization of GmVP2 in transgenic soybean hairy roots demonstrated that GmVP2 encoded a plasma membrane transporter that mediated H + exudation. Meanwhile, GmVP2-overexpression in Arabidopsis thaliana resulted in enhanced root H + exudation, promoted root growth, and improved sparingly soluble Ca-P utilization. The improved root growth caused by GmVP2-overexpression might due to the differential expression of genes relative to hormone and flavonoid metabolisms, and root development. Overexpression of GmVP2 also changed the rhizospheric microbial community structures, as reflected by a preferential accumulation of Acidobacteria. These results suggest that GmVP2 mediates H + exudation in root response to Pi starvation, which coordinately influences plant growth, sparingly soluble P-sources mobilization and microbial community structures.