An association between past levels of ozone column depletion and the pollen morphology of the model angiosperm Arabidopsis thaliana L

Abstract

The currently reduced stratospheric ozone layer remains sensitive to destructive anthropogenic and natural inputs. We hypothesised that a sudden increase in surface ultraviolet-B (UV-B) irradiation, as may have occurred in a past mass extinction event, would have a significant effect on the pollen grain morphology of the model angiosperm Arabidopsis thaliana L. Plants of Arabidopsis thaliana in controlled-environment chambers were exposed to an increase in UV-B irradiation associated with an ozone column reduction of 70%. Pollen grains were examined with light and electron microscopy for morphological abnormalities. In this study, we found that a wild-type Arabidopsis thaliana accession showed a significant increase in the proportion of pollen grain morphological abnormalities in response to the increase in UV-B irradiation. Plants exposed to ambient conditions in early growth had less pollen morphological abnormalities when exposed to a subsequent increase in UV-B. Results here suggest that any future decrease in stratospheric ozone similar to that implicated in the end-Permian mass extinction event may increase angiosperm pollen morphological abnormalities, with uncertain and potentially negative consequences for plant reproductive success.