Phospholipid Networks as Metabolic Hubs and Signaling Integrators in Plant Development and Stress Adaptation.

Phospholipids function as dynamic regulators of plant growth and environmental adaptation, extending well beyond their structural roles in biological membranes. This review synthesizes the phospholipid metabolic network and its regulatory functions in plant physiology. We first describe enzymatic reactions and acyl-chain remodeling in phospholipid biosynthesis, and then examine the interaction between phospholipid metabolism and auxin signaling, focusing on phosphatidic acid (PA) and phosphoinositide phosphate (PIP). These lipid molecules regulate the polarization and vesicular trafficking of PIN-FORMED proteins via endocytosis and phosphorylation-dependent mechanisms, thereby controlling auxin distribution during development and stress adaptation. Particular emphasis is placed on PA, a multifunctional signaling lipid that serves as a central molecular hub. PA coordinates hormonal, stress, and circadian signals by engaging and modulating a broad spectrum of protein targets, including kinases, phosphatases, and transcription factors. We also discuss the emerging and evolutionarily conserved functions of phospholipid signaling in cell fate determination, drawing parallels from mammalian cell reprogramming to the regulation of plant cell totipotency and root patterning. Collectively, these findings underscore the critical role of phospholipid-mediated signaling in converting metabolic and environmental cues into developmental reprogramming, providing novel theoretical and functional frameworks for future research in plant lipid biology.