Effects of UV-B Radiation on Pollen Germination and Tube Growth: A Global Meta-Analysis.

Despite widespread recognition of pollen's potential sensitivity to ultraviolet -B (UV -B) radiation (280-315 nm), there remains ongoing debate surrounding the extent and mechanisms of this effect. In this study, using published data on pollen germination and tube growth including 377 pair -wise comparisons from 77 species in 30 families, we present the first global quantification of the effects of UV -B radiation on pollen germination and tube growth, along with its underlying mechanisms. Our results showed a substantial reduction in both pollen germination and tube growth in response to UV -B radiation, affecting 90.9 % and 84.2 % of species, respectively. Notably, these reductions exhibited phylogenetic constraints, highlighting the role of evolutionary history in shaping the sensitivity of pollen germination and tube growth to UV -B radiation. A negative correlation between elevation and the sensitivity of pollen tube growth was detected, suggesting that pollens from plants at higher elevations exhibit greater resistance to UV -B radiation. Our investigation also revealed that the effects of UV -B radiation on pollen germination and tube growth were influenced by a range of abiotic and biotic factors. Nevertheless, the intensity and duration of UV -B radiation exposure exhibited the highest explanatory power for the effects on both pollen germination and tube growth. This suggests that the responses of pollens to UV -B radiation are profoundly influenced by its dose, a critical consideration within the context of global change. In conclusion, our study provides valuable insights into the diverse responses of pollen germination and tube growth to UV -B radiation, highlighting the environment and species -dependent nature of pollen's susceptibility to UV -B radiation, with substantial implications for our understanding of the ecological and agricultural consequences of ongoing changes in UV -B radiation.