Piriformospora indica colonization reprograms plants to improved P-uptake, enhanced crop performance, and biotic/abiotic stress tolerance

Piriformospora indica is an endophytic fungus that promotes plant growth by establishing mutually beneficial alliances with plant roots reminiscent of arbuscular mycorrhizal fungi. It solubilizes soil inaccessible organic P to readily available Pi, thus, constitutes an indirect source of phosphate for plant growth under P limitation. In exchange, P. indica derives photosynthates (carbon) from host plant cell that is necessary for its metabolic processes and survival. This fungus modifies both biosynthetic and signaling pathways of phytohormones to regulate plant growth and local/systemic immune responses. However, detailed mechanisms describing how P. indica adjusts phytohormones homeostasis to promote mutual benefits during its association with plants remain to be clarified. In addition, P. indica amends tolerance to biotic and abiotic stress factors in a wide spectrum of plant species. Although several research output has been reported to elicit the agronomic importance of P. indica, the molecular mechanisms underlying P. indica growth promoting potential remain complex and poorly defined. Thus, this review focuses on recent advances trying to unravel the molecular mechanisms responsible for the ability of P. indica to significantly promote growth, and confer stress acclimation capacity to plants grown in natural ecosystems. Finally, the review highlights the potential avenues of further research to strengthen this symbiotic association between P. indica and plants.