Desiccation protects two Antarctic mosses from ultraviolet-B induced DNA damage

Abstract

Antarctic mosses live in a frozen desert, and are characterised by the ability to survive desiccation. They can tolerate multiple desiccation-rehydration events over the summer growing season. As a result of recent ozone depletion, such mosses may also be exposed to ultraviolet-B radiation while desiccated. The ultraviolet-B susceptibility of Antarctic moss species was examined in a laboratory experiment that tested whether desiccated or hydrated mosses accumulated more DNA damage under enhanced ultraviolet-B radiation. Accumulation of cyclobutane pyrimidine dimers and pyrimidine (6–4) pyrimidone dimers was measured in moss samples collected from the field and then exposed to ultraviolet-B radiation in either a desiccated or hydrated state. Two cosmopolitan species, Ceratodon purpureus (Hedw.) Brid. and Bryum pseudotriquetrum (Hedw.) Gaertn., B.Mey. & Scherb, were protected from DNA damage when desiccated, with accumulation of cyclobutane pyrimidine dimers reduced by at least 60% relative to hydrated moss. The endemic Schistidium antarctici (Cardot) L.I. Savicz & Smirnova accumulated more DNA damage than the other species and desiccation was not protective in this species. The cosmopolitan species remarkable ability to tolerate high ultraviolet-B exposure, especially in the desiccated state, suggests they may be better able to tolerate continued elevated ultraviolet-B radiation than the endemic species.

Effects of enhanced UV-B radiation on hydroxycinnamic acid derivatives extracted from different cell compartments in the aquatic liverwort Jungermannia exsertifolia subsp. cordifolia

“…This is consistent with the target character of DNA with respect to UV‐B (Jansen et al 1998) so that this response seems to be largely UV‐B‐specific. Our finding is also in agreement with previous studies conducted on bryophytes, because DNA damage increased in samples exposed to enhanced UV‐B under laboratory (Lud et al 2002, Otero et al 2006, Turnbull et al 2009) and field (Lud et al 2002, 2003) conditions. However, DNA damage was not detected when bryophytes were exposed to ambient UV‐B levels (Núñez‐Olivera et al 2009), unless the environmental conditions were so harsh that prevented DNA repair, as occurs in the Antarctic (Turnbull and Robinson 2009).…”

Physiological ecology of photosynthesis in Prasiola stipitata (Trebouxiophyceae) from the Bay of Fundy, Canada

“…While Davison and Pearson (1996) suggested that Huppertz et al (1990) did not have sufficient data to demonstrate this, it has subsequently been confirmed in a fern (Muslin & Homann 1992). Furthermore, Turnbull et al (2009) suggested that desiccation protected Antarctic mosses from UV-B induced DNA damage. Given the extreme exposure to both high PAR and high UV radiation experienced by P. stipitata, desiccation tolerance would appear to be a key component of its adaptation to the open, supralittoral environment.…”

“…Furthermore, Turnbull et al . () suggested that desiccation protected Antarctic mosses from UV‐B induced DNA damage. Given the extreme exposure to both high PAR and high UV radiation experienced by P. stipitata , desiccation tolerance would appear to be a key component of its adaptation to the open, supralittoral environment.…”

What affects the probability of biological invasions in Antarctica? Using an expanded conceptual framework to anticipate the risk of alien species expansion

“…However some Antarctic mosses have been found to quickly deploy sufficient UV protection (Newsham et al 2002;Green et al 2005). Negative effects of UV-B can be reduced by various 1 3 defense mechanisms (Robinson et al 2003;Turnbull et al 2009). However, their launch is associated with the additional costs, which may prove to be too large, especially for organisms living at the physiological limits of survival.…”