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

Plant roots simultaneously rely on root hairs and the rhizosphere microbiome to acquire poorly accessible 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 could 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 arbuscular mycorrhizal fungi (AMF) staining, we quantified the enrichment of bacterial P-cycling genes and 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 very early seedling development, where P mineralizing bacteria dominated over P solubilizing bacteria. The AMF symbiosis was only fully established after several weeks of growth, but then arbuscularisation became dominant over bacterial P mineralization in the root hair mutant. Wheat can recruit and rely on bacterial P mineralization to meet their P needs before the AMF symbiosis is fully dominant and then release these bacteria once the AMF symbiosis is developed.