Document: CYN-3-46-13

Responses to ambient UV radiation and R:FR vary between sun and shade populations of Impatiens capensis.

WEINIG, C.* and J.SCHMITT

Brown University, Providence, RI 02912, USA ¹

Abstract:
Exposure to ultra-violet radiation (UV) affects many aspects of plant development, including plant architecture and the production of leaf secondary compounds (anthocyanins and flavonoids). We examined 1) the phenotypic and fitness effects of UV, 2) the combined effects of UV and the ratio of red:far-red light (R:FR), and 3) the relative responses of Impatiens capensis populations derived from woodland and clearing sites to UV. Seedlings from each population were exposed to either high R:FR typical of sunlight or low R:FR characteristic of foliar shade, after which plants were moved into ambient UV or UV-removal treatments. Preliminary analyses indicate that the negative effects of UV exposure on reproductive output were greater in plants initially experiencing low relative to high R:FR. These results suggest a cost to stem elongation in terms of subsequent susceptibility to UV damage. UV stimulated the production of both anthocyanins and flavonoids. However, higher anthocyanin concentrations were correlated with lower fitness in clearing population. Relative to the clearing population, the fitness of the woodland population was more detrimentally affected by exposure to UV, despite its greater increases in anthocyanin production under UV conditions. Increased anthocyanin production under UV may therefore be a stress response rather than an adaptive one. The greater tolerance of the clearing population to UV suggests that populations with an evolutionary history of UV exposure evolve mechanisms to limit damage.

Keywords: anthocyanins, flavonoids, R:FR, UV, local adaptation, phenotypic plasticity

This abstract is being presented at: 8:30 AM in session:
Oral Session #69: UV-B.