Abstract 1219 Optimizing UV-B-induced changes in flavonoids in cucumber and Arabidopsis seedlings

Brief (1–100 min) irradiations with two different ultraviolet-B (UV-B) wave bands induced increases in the UV-absorbing pigments extracted from cucumber (Cucumis sativus L.) and Arabidopsis Thaliana seedlings. Multiple genetic strains of cucumber and Arabidopsis seedlings were tested to determine the optimum time between irradiation and pigment extraction, and the optimum UV-B exposure. Seedlings were grown under dim red light (0.2 μmol m-2 sec-1) and irradiated with 5kJ m−2 of either full spectrum UVB (FS UV-B, 280- 340 nm with a peak at 313 nm)d long-wavelength UVB (LW UV-B, 300-340 nm with a peak at 313 nm). Pigments were extracted from cucumber and Arabidopsis hypocotyls and placed in methanol/1% HCl extracts. Spectra were taken from 250–400 nm. Preliminary results confirm that tissue extracts taken 24 h after irradiation showed an overall increase in absorption and peaks at ∼260nm and ∼320nm for both types of irradiation, in contrast to previous findings where only FS UV-B induced a peak at ∼260 nm. We were able to replicate the earlier findings with 3 cucumber cultivars, and one cultivar, BoothbyBlonde, exhibited the largest difference between the FS UV-B and LW UV-B at 260 nm, indicating that there is a unique pigment worth researching further. Indirect evidence indicates that the pigment is a flavonoid. Replication of Arabidopsis results are in progress. This research was funded by Trinity University's Biological Sciences Undergraduate Research Fellowship Program (BSURF).