MYCOLab Ai Logo - gold and army green

Starve or share? Phosphate availability shapes plant–microbe interactions

Summary

Plants need phosphate to survive, but it’s hard to find in soil. To solve this problem, plants partner with beneficial fungi and bacteria that help them absorb more phosphate. A master control system inside plants called PHR decides whether to be friendly with these helpful microbes or to defend against harmful ones, depending on how much phosphate is available. This clever system helps plants thrive even when nutrients are scarce.

Background

Phosphorus is an essential macronutrient for plant growth, but phosphate (Pi) availability is limited in most soils. Plants have evolved phosphate starvation responses (PSRs) and symbiotic associations with microorganisms to improve Pi uptake. The PHR–SPX signaling module regulates these responses and controls interactions with beneficial and detrimental microbes.

Objective

This review examines how phosphate availability shapes plant–microbe interactions through the PHR–SPX regulatory module. The authors discuss how plants monitor phosphate status and coordinate responses involving arbuscular mycorrhiza, root nodule symbiosis, and microbiome composition in response to nutrient availability.

Results

The PHR transcription factor serves as a central integrator linking phosphate sensing with biotic interactions, activating symbiotic programs under phosphate deficiency while suppressing immunity to favor beneficial microbe recruitment. The PHR–SPX module is evolutionarily conserved and regulates AM colonization, root nodule symbiosis, and root microbiome composition through context-dependent mechanisms.

Conclusion

The PHR–SPX signaling module represents an ancient regulatory toolkit co-opted during plant evolution to fine-tune biotic interactions in response to environmental nutrient cues. Further mechanistic understanding of how phosphate availability regulates both beneficial and detrimental plant–microbe interactions is essential for future research and agricultural applications.
  • Published in:PLoS Pathogens,
  • Study Type:Review,
  • Source: PMID: 41118346, DOI: 10.1371/journal.ppat.1013601
Scroll to Top