Functional acclimation to solar UV-B radiation in Gunnera magellanica, a native plant species of southernmost Patagonia

GIORDANO C. V.; MORI T.; SALA O. E.; SCOPEL A. L.; CALDWELL M. M.; BALLARÉ C. L.

PLANT, CELL AND ENVIRONMENT (PRINT)

Blackwell Publishing

Año: 2003 vol. 26 p. 2027 - 2036

0140-7791

The ecosystems of Tierra del Fuego (in southern Patagonia, Argentina) are seasonally exposed to elevated levels of ultraviolet-B radiation (UV-B: 280-315 nm), due to the passage of the “ozone hole” over this region. In the  present work we tested the effects of solar UV-B and UV-A (315-400 nm) on two UV-B defense related processes: the accumulation of protective UV-absorbing compounds and DNA repair. We found that the accumulation of UV-absorbing sunscreens in G. magellanica leaves was not affected by plant exposure to ambient UV radiation. Photorepair was the predominant mechanism of cyclobutane-pyrimidine dimer (CPD) removal in G. magellanica. Plants exposed to solar UV had higher CPD repair capacity under optimal conditions of temperature (25º C) than plants grown under attenuated UV. There was no measurable repair at 8º C. The rates of CPD repair in G. magellanica plants were modest compared to other species and, under equivalent conditions, were about 50 % lower than the repair rates of Arabidopsis thaliana (Ler ecotype). Collectively our results suggest that the susceptibility of G. magellanica plants to the current ambient levels of solar UV-B in southern Patagonia may be related to a low DNA repair capacity.