Impact of climate change on plant phenology: Molecular and ecophysiological perspectives

Plant phenology, defined as the timing of recurring biological events such as leaf emergence, flowering, fruiting, and senescence, is one of the most sensitive indicators of climate change. Over recent decades, rising temperatures, altered precipitation regimes, elevated atmospheric CO₂ concentrations, and increased climatic extremes have substantially modified phenological patterns across terrestrial ecosystems. This review synthesizes current knowledge on the impact of climate change on plant phenology by integrating molecular, physiological, and ecological perspectives. The primary objective is to examine how climate-driven environmental cues are perceived and transduced at the molecular level, how these signals interact with ecophysiological processes, and how such interactions ultimately shape phenological outcomes across biomes. We summarize global and regional phenological trends, highlight advances in understanding flowering-time gene networks, temperature and photoperiod sensing pathways, and epigenetic mechanisms, and link these molecular processes with plant water relations, carbon allocation, and hormonal regulation. Evidence indicates that although phenological plasticity can buffer plants against moderate climatic variation, mismatches between phenological events and interacting species, combined with constraints imposed by photoperiod and chilling requirements, may limit adaptive capacity under future warming scenarios. We conclude that mechanistic integration of molecular biology, ecophysiology, and long-term ecological observations is essential for improving phenological predictions and informing climate adaptation strategies in agriculture, forestry, and biodiversity conservation.