Trehalose–abscisic acid pathway feedback loops in wheat – Piriformospora indica symbiosis: Mechanisms and drought resilience

Drought stress poses a significant threat to global cereal productivity, particularly in water-sensitive crops such as wheat ( Triticum aestivum ). Recent advances highlight the symbiotic interplay between cereal crops and the endophytic fungus Piriformospora indica (syn. Serendipita indica ) in enhancing drought resilience through intricate biochemical and hormonal signaling networks. Central to this interaction is trehalose, a disaccharide metabolite produced and secreted by P. indica at the root-fungal interface. Trehalose accumulation at this mycorrhizal junction as well as symbiotic association-driven trehalose not merely a metabolic artifact but this symbiosis actively engages with host plant physiology by modulating abscisic acid (ABA) signaling, inducing stomatal closure, and stabilizing membranes and proteins under osmotic stress. In cereals crops, studies now reveal that P. indica -wheat-trehalose driven metabolic regulations (TPPs, TPSs, and trehalase) can influence drought-responsive transcription factors (DREBs, AREBs), ROS signaling, and ABA biosynthetic genes (e.g., NCED , ABA2 ). This facilitates enhanced root growth, deeper soil water extraction, and efficient stomatal conductance control in drought stress management and overall yield enhancement in wheat crop. This review consolidates mechanistic insights into how P. indica –wheat induced trehalose metabolism converges with ABA signaling to fortify cereal crops such as wheat against drought, offering a promising avenue for sustainable agriculture. • Piriformospora indica colonization with wheat elevates ABA biosynthesis (NCED) and primes the PYR/PYL–SnRK2–ABF signaling cascade. • ABA signaling drives transcription of TPP genes, resulting in significant trehalose accumulation in wheat. • The trehalose–ABA network improves root water uptake, osmotic adjustment, and antioxidant capacity under drought. • Wheat colonization by P. indica improves tillering, grain yield, and pathogen resistance, highlighting its utility as a bioinoculant. • This symbiosis highlights P. indica as a promising biopriming tool for climate-smart wheat production.