Whilst light is essential for photosynthesis and development of plants, both excess photosynthetically active radiation and certain wavelengths (e.g. high energy ultraviolet-B) radiation can be damaging. In mid-summer high levels of photosynthetically active radiation, naturally brings higher levels of UV radiation. However, reduction of stratospheric ozone directly above Antarctica presents another challenge for plants living in the unique Antarctic climate. Depletion of the ozone layer reduces its effectiveness as a UV filter. This subjects bryophytes, the dominant plant life in Antarctica, to elevated and harmful doses of UV-B radiation; levels of which can impair vital cellular contents and processes, such as DNA, chlorophyll and photosynthesis.
Given the high stress environments that many bryophytes inhabit, from hot or frozen deserts to alpine habitats with high incident UV-B radiation, it is unsurprising that they have a suite of photoprotective strategies. Whilst bryophytes share many of these strategies with vascular plants, there are key differences in what is available to bryophytes. Some of these differences pertain to structural features, such as protective epidermal layers, that are available to vascular plants but not generally to bryophytes. Bryophytes thus have to invest more in cellular level photoprotection than vascular plants.
This talk will explore the various mechanisms Antarctic bryophytes (mosses and liverworts) employ to survive under elevated UV-B radiation in an icy desert. This includes the accumulation of specialised compounds called UV-absorbing or -screening compounds that directly or indirectly protect them from UV-induced damage. These often complex sunscreens are highly valuable for many mosses and liverworts surviving the harsh Antarctic environment.