ABSTRACT

Plants experience many stresses, including extreme temperatures, drought, and ultraviolet (UV) light. UV light is a harmful to DNA and proteins. In flowering plants, pollen is particularly susceptible to UV damage, but dark pigments in flower petals may protect the pollen by absorbing UV light. The intensity of UV light reaching Earth has increased greatly during the 20th century and may continue to increase, especially in some regions. This project explores whether protective pigmentation in flowers has increased in response to increasing amounts of UV light. Because flower color is important for attracting pollinators, understanding how it may have changed is necessary to understand how effectiveness of pollination may also have changed. Pollination effectiveness, in turn, is important for the economic success of many agricultural crops and for the ecological well-being of all flowering plants. This project will also provide research experiences and mentoring for students from underrepresented groups, and will engage the general public through outreach activities at multiple events.

Researchers will test the prediction that temporal increases in UV-B radiation have driven increases in UV-absorbing pigmentation in the petals of flowers. Because UV-B has increased most in polar and temperate regions during the last century, they predict that species with polar and temperate distributions will display larger increases in UV-absorbing pigmentation than sub-tropical species. Additionally, the researchers will test the prediction that species with pollen-bearing structures exposed to sunlight will respond to changes in UV-B, while those with pollen structures recessed within the flower (protected) will not. Researchers will use herbarium specimens and bioclimatic databases to gather data on flower pigmentation and abiotic conditions for 75 diverse taxa with different geographic distributions. They will also sample color across a 55-year time span and will use comparative models to assess whether rapid changes in UV-B have elicited rapid change in flower coloration.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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