Plant phosphate status influences root biotic interactions.

Phosphorus (P) deficiency stress in combination with biotic stress(s) severely impacts crop yield. Plant responses to P deficiency overlapping with that of other stresses exhibit a high degree of complexity involving different signaling pathways. On one hand, plants engage with rhizosphere microbiome/ arbuscular mycorrhizal fungi for improved phosphate (Pi) acquisition and plant stress response upon Pi deficiency, on the other, this association is inhibited under Pi sufficiency. This nutrient-dependent response is highly regulated by phosphate starvation response (PSR) mediated by the master regulator, PHR1 and its homolog, PHL. It is interesting to note that Pi status (deficiency/sufficiency) has a varying response (positive/negative) to different biotic encounters (beneficial microbes/opportunistic pathogens/insect herbivory), through a coupled PSR-PHR1-immune response. This also involves crosstalk among multiple players including transcription factors, defense hormones, microRNAs, and phosphate transporters, among others influencing the plant-biotic-phosphate interactions. We provide a comprehensive view of these key players involved in maintaining a delicate balance between Pi homeostasis and plant immunity. Finally, we propose strategies to utilize this information to improve crop resilience to P deficiency in combination with biotic stresses.