The chloroplast-mitochondria interaction under water extremes: Insights into metabolic tug-of-war.

Plants respond to water extremes through dynamic, organelle-level reprogramming of resource allocation rather than metabolic shutdown. Recent advances suggest that drought and flooding induce coordinated metabolic reorganization between chloroplasts and mitochondria, shifting energy distribution from growth to stress acclimation via retrograde signaling pathways. These signals are integrated by the trehalose-6-phosphate (Tre6P)-sucrose non-fermenting 1-related protein kinase 1 (SnRK1)-target of rapamycin (TOR) network, a central regulatory hub that interprets carbon and energy status to modulate stress-responsive metabolic and physiological outcomes. This systemic coordination is also modulated by hormone reprogramming and shaping adaptive phenotypic responses. Emerging technologies, spanning from organelle-specific metabolomics to synthetic biology, provide a framework to engineer inter-organellar communication. Here, we review recent advances in chloroplast-mitochondria metabolic coordination, retrograde signaling, and energy-sensing networks under water extremes, and discuss future strategies to engineer metabolic crosstalk for improving crop stress resilience and growth under adverse environments.