Molecular mechanisms underlying negative effects of transient heatwaves on crop fertility

Transient heatwaves occur more frequently with climate warming, yet their impacts on crop yield are severely underestimated and even overlooked. Heatwaves spanning mere days or even hours during sensitive stages (e.g., microgametogenesis and flowering) can significantly reduce crop yield by disrupting plant reproduction. Recently, advancements in multi-omics and GWAS analysis have shed light on specific organs (e.g., pollen, lodicule, and style), key metabolic pathways (sugar and reactive oxygen species (ROS) metabolisms, Ca2+ homeostasis), and essential genes for transient heatwaves responses during the most sensitive stages in many crops. Based on this, this review places particular emphasis on the crop's heat-sensitive stages, using pollen development, floret opening, pollination, and fertilization as the central narrative thread. Complementing by key parts such as lodicule and tapetum, the multifaceted effects of transient heatwaves and their molecular basis are systematically demonstrated. A number of heat-tolerant genes for these processes have been identified in major crops such as maize and rice. The mechanisms and key heat-tolerant genes shared over different stages potentially facilitate the improvement of heat-tolerant crops more precisely.