Arbuscular Mycorrhizal Symbiosis Enables Efficient Phosphorus Uptake in Sorghum Accessions With Contrasting Root Traits

Phosphorus (P), an essential nutrient, is apparently unavailable to plants due to strong sorption in soils. Plants with shallow root systems and high surface area exhibit high P acquisition efficiency (PAE). Arbuscular mycorrhizal fungal (AMF) symbiosis can also enhance PAE. However, whether AMF symbiosis will equally benefit crop accessions with contrasting root traits is less known. We selected sorghum accessions that varied in root traits to evaluate P uptake strategies and assessed changes in root traits, acid-phosphatase activity, primary and specialised metabolome in the presence of AMF, and under limited and stratified P availability. Our results revealed that regardless of the inherent accession differences in root traits, all accessions had higher shoot P and biomass with AMF inoculation. AMF-inoculated plants had lower specific root length, higher hyphal length and acid phosphatase activity than the non-inoculated control, indicating that plants can enhance PAE with AMF, irrespective of inherent accession differences. The AMF induced similar changes in root metabolome, where AMF-inoculated plants had higher organic acids and specialised metabolites necessary for a functional symbiosis. Our results emphasise the critical role of AMF in efficient P uptake regardless of inherent root traits, which should be considered while selecting crop accessions for improved PAE.