Abstract
Pollen, a pivotal stage in the plant reproductive cycle, is highly
sensitive to temperature fluctuations, impacting seed quality and
quantity. While the importance of understanding pollen temperature
limtits (Tmin, Topt, Tmax – collectively PTLs) is recognized, a
comprehensive synthesis of underlying drivers is lacking. Here, we
examined PTLs, correlating them with vegetative tissue thermotolerance
and assessing variability at the intra- and interspecific levels across
198 species with contrasting phylogeny, cultivation history, biology and
ecology. At the species level, the PTLs range from 6.1 to 39.5
0C, with considerable differences among growth forms
and cultivation histories. Positive correlations were found between PTLs
and leaf/stem temperature tolerances. Notably, pollen cold tolerances
varied significantly across species populations, while Topt and Tmax
values remained stable. Phylogenetic analysis revealed family-level
conservation in pollen cold tolerance, contrasting with heat tolerance’s
independence from evolutionary history. Climate emerged as a significant
PTL driver, with species at higher elevations and latitudes exhibiting
enhanced cold and heat tolerance. Cultivated species displayed narrower
temperature tolerances (10.3-39.9 °C) than their wild counterparts
(5.2-42.3 °C), highlighting potential crop vulnerabilities to global
warming. Herbaceous plants exhibited superior tolerance to both low and
high temperatures compared to shrubs and trees, reflecting divergent
thermal conditions during anthesis. This study illuminates complex
relationships between pollen temperature limits, plant characteristics,
and environmental factors, providing crucial insights into climate
change impacts on plant reproduction.