Wheat responds to lack of root hairs with recruitment of bacteria harboring P mineralization genes and increased arbuscular mycorrhizal colonization

Plant roots simultaneously rely on root hairs and the rhizosphere microbiome to acquire phosphorus (P) from the soil, but the full potential of the plant to utilize its microbiome for nutrient capture has yet to be fully understood. We hypothesized that a wheat mutant defective in root hair elongation would recruit more P-cycling bacteria and AMF compared to its wild-type background to compensate for the loss of root hairs.

Through quantitative polymerase chain reaction and staining, we quantified the enrichment of bacterial P-cycling genes and arbuscular mycorrhizal fungi (AMF) colonization across different stages of wheat development and in differentially P fertilized soils in the presence and absence of root hair elongation.

The loss of root hair elongation led to an enrichment of P-cycling bacteria during early seedling development, and P mineralizing bacteria dominated over P solubilizing bacteria. The AMF symbiosis was only fully established after several weeks of growth, and the loss of root hair elongation promoted mycorrhizal formation.

Wheat can recruit and utilize bacterial P mineralization to meet its P needs before the AMF symbiosis is established, but the colonization of these bacteria is no longer prioritized once the AMF symbiosis is developed.