Molecular regulation of pollen responses to abiotic stress in flowering plants: Mechanisms, models and future directions

Pollen development and function are highly sensitive to abiotic stresses such as heat, drought, salinity, and cold, making pollen one of the most vulnerable stages in the life cycle of a plant. These stress factors affect pollen viability and disrupt pollen tube growth and germination, directly impacting fertilization success and thereby reducing crop yield. Advances in plant molecular biology have helped identify several stress-responsive genes and regulatory mechanisms that govern pollen responses to stress, including transcription factors, hormonal signalling components, ion transporters, and epigenetic regulators. Studies across different model plants and crop species have utilized techniques like RNA sequencing, qRT-PCR, multi-omics, and in vitro assays to unravel gene expression changes and molecular pathways associated with pollen responses to abiotic stress. However, molecular insights into pollen responses to salinity, cold, and oxidative stress remain comparatively limited in contrast to heat and drought stress. This mini-review provides a gene-centred synthesis of the molecular mechanisms underlying pollen responses to abiotic stress and highlights shared regulatory nodes that integrate multiple stress-response pathways. By comparing mechanisms reported across different plant species and stress types, this review also emphasizes understudied areas such as pollen responses to cold, salinity, and oxidative stress, and outlines key knowledge gaps that must be addressed to improve pollen adaptability and reproductive stability under changing climatic conditions.