PHOTOSYNTHETICA

Photosynthetica 2010, 48(2):287-293 | DOI: 10.1007/s11099-010-0035-2

The short- and long-term response of Scrippsiella trochoidea (Pyrrophyta) to solar ultraviolet radiation

W. C. Guan^1,2, S. H. Lu^1,*

¹ College of Life Science South China Normal University, Guangzhou, Guangdong, China

² School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang, China

To assess the short- and long-term impacts of UV radiation (UVR, 280-400 nm) on the microalga Scrippsiella trochoidea, we exposed cells to three different radiation treatments (PAB: 280-700 nm, PA: 320-700 nm, and P: 400-700 nm). A significant decrease in the photochemical efficiency (Φ_PSII) at high irradiance (100% of incident solar radiation, 216.0 W m^-2) was observed. Photoinhibition was reduced from 62.7 to 10.9% when the cells were placed in 12% solar radiation (26.1 W m^-2). In long-term experiments (11 days) using batch cultures, cell densities during the first 5 days were decreased under treaments P, PA, and PAB, reflecting a change in the irradiance experienced in the laboratory to that of incident solar irradiance. Thereafter, specific growth rates increased and UV-induced photoinhibition decreased, indicating acclimation to solar UV. Cells were found to exhibit both higher ratios of repair to UV-related damage, shorter period for recovery and increased concentrations of UV-absorbing compounds (UV_abc), whose maximum absorption was found to be at 336 nm. Our data indicate that S. trochoidea is sensitive to ultraviolet radiation, but was able to acclimate relatively rapidly (ca. 6 days) by synthesizing UV_abc and by increasing the rates of repair processes of D1 protein in PSII.

Keywords: growth; photochemical efficiency; Scrippsiella trochoidea; UVR; Φ_PSII

Received: January 7, 2010; Accepted: May 9, 2010; Published: June 1, 2010Show citation