Jasmine Gill

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.

SUMMARY: Rhizobiome confer stress tolerance to ruderal plants, yet their ability to alleviate stress in crops is widely debated, and the associated mechanisms are poorly understood. We monitored the drought tolerance of maize (Zea mays) as influenced by the cross‐inoculation of rhizobiota from a congeneric ruderal grassAndropogon virginicus(andropogon‐inoculum), and rhizobiota from organic farm maintained under mesic condition (organic‐inoculum). Across drought treatments (40% field capacity), maize that receivedandropogon‐inoculumproduced two‐fold greater biomass. This drought tolerance translated to a similar leaf metabolomic composition as that of the well‐watered control (80% field capacity) and reduced oxidative damage, despite a lower activity of antioxidant enzymes. At a morphological‐level, drought tolerance was associated with an increase in specific root length and surface area facilitated by the homeostasis of phytohormones promoting root branching. At a proteome‐level, the drought tolerance was associated with upregulation of proteins related to glutathione metabolism and endoplasmic reticulum‐associated degradation process. Fungal taxa belonging to Ascomycota, Mortierellomycota, Archaeorhizomycetes, Dothideomycetes, and Agaricomycetes inandropogon‐inoculumwere identified as potential indicators of drought tolerance. Our study provides a mechanistic understanding of the rhizobiome‐facilitated drought tolerance and demonstrates a better path to utilize plant–rhizobiome associations to enhance drought tolerance in crops.