Auxin-mediated regulation and functional adaptation of leaf veins under heat stress

Elevated global temperatures threaten crop yield and quality by impairing plant hydraulic efficiency and photosynthetic stability, hence highlighting the significance of vascular architectural plasticity in heat stress tolerance. Leaf vein architecture, the principal conduit for water, nutrients, and photosynthates, provides structural support and controls gas exchange, which are critical for sustaining growth and productivity under heat stress. Increasing evidence shows that vascular plasticity, including adjustments in vein density and patterning, underpins plant resilience by maintaining physiological homeostasis. This review summarizes the current knowledge of how heat stress influences leaf and vein structure, with an emphasis on the molecular regulatory networks that drive vascular structural adaptation. We highlight the central role of auxin in coordinating vascular differentiation through its regulation of biosynthesis, polar transport, and signalling transduction, and discuss how auxin integrates with other hormonal pathways to fine-tune vascular traits in response to environmental cues. Particularly, we focus on the unique vein patterning strategies and physiological function in the grass family, including species of many major food and cash crops with agricultural and ecological significance. By integrating these insights, we propose a framework that links vascular plasticity with plant development and yield, offering research insights and practical guidance for breeding heat-resilient crop varieties.