Comparative metabolomics of released pollen during dispersal reveals metabolic adaptations to cold and heat stress
Heat and cold stress can severely impair released pollen, reducing pollen viability and ultimately limiting fertilization and crop productivity. Following release, pollen is directly exposed to fluctuating environmental temperatures, necessitating adaptive metabolic mechanisms to sustain viability during dispersal. In response to temperature stress, pollen undergoes metabolic reprogramming that supports biochemical and physiological adaptation. However, the metabolic basis of pollen tolerance to extreme temperatures remains incompletely understood. In this study, biochemical assays combined with LC-MS-based untargeted metabolomic profiling were employed to investigate metabolic changes in released pollen exposed to low (15 {degrees}C) and high (35 {degrees}C) temperature stress. A total of 484 metabolites were detected, of which 147 were significantly altered between cold- and heat-stressed pollen, including 61 upregulated and 86 downregulated metabolites. Differentially regulated metabolites spanned multiple classes, including amino acids, flavonoids, long-chain fatty acids, sugars, and polyamines. Pathway enrichment analysis highlighted biologically relevant perturbations in amino acid and nucleic acid metabolism, including purine metabolism, arginine biosynthesis, and glutathione metabolism. Collectively, these findings demonstrate temperature-dependent metabolic adjustments in released pollen and provide new insights into the biochemical strategies underlying pollen tolerance to heat and cold stress. This work advances our understanding of pollen metabolic adaptation during dispersal and provides a foundation for identifying metabolic indicators relevant to crop fertility under changing climatic conditions. These findings provide a metabolomic framework for understanding pollen thermotolerance during dispersal and offer a resource for future studies on reproductive resilience under climate change.