Photosynthetic Attributes of Antarctic Plants

Metadata record for data from ASAC Project 244 See thelink below for public details on this project.From the abstracts of the referenced papers:Photoinhibition of Grimmia antarctici (Grimmia is now known as Schistidium) during the summer at Casey, East Antarctica, was indicated by a reduction in photosynthetic capacity (light saturated photosynthetic rate), photosynthetic efficiency (photon yield of O2 evolution), photochemical quantum yield (ratio of variable to maximum fluorescence) and rate of fluorescence quenching when plants were exposed to moderate light at low temperature. We suggest that photoinhibition is a major factor limiting bryophyte productivity in Antarctic ecosystems.Variation in leaf pigmentation from green to ginger is observed for Ceratodon purpureus (Hedw.) Brid. in Antarctica. Electron microscopy of ginger and green leaves reveals less thylakoid stacking, a response to greater light exposure, in the ginger leaves. In extremely exposed sites C. purpureus has low chlorophyll a/b ratios which correlate with decreased 77K chlorophyll fluorescence, indicating damage to chlorophyll a. Pigment analysis of ginger moss shows that even when the chlorophyll a/b ratio has not decreased the pigment composition differs from green moss. The increase in anthocyanin and decrease in chlorophyll concentrations largely account for the visual change from green to ginger. The ratio of total carotenoid to chlorophyll varies from 0.35 in green moss to 0.55 in the ginger moss, with violaxanthin increased preferentially. Since these changes in pigmentation are consistent with photoprotection and they are linked to light depended variations in chloroplast structure, it appears that photoprotective pigments are a useful adaptation for the bright Antarctic environment.