Outdoor Studies on the Effects of Solar UV-B on bryophytes: Overview and Methodology

Abstract

In this review all recent field studies on the effects of UV-B radiation on bryophytes are discussed. In most of the studies fluorescent UV-B tubes are used to expose the vegetation to enhanced levels of UV-B radiation to simulate stratospheric ozone depletion. Other studies use screens to filter the UV-B part of the solar spectrum, thereby comparing ambient levels of UV-B with reduced UV-B levels, or analyse effects of natural variations in UV-B arising from stratospheric ozone depletion. Nearly all studies show that mosses are well adapted to ambient levels of UV-B radiation since UV-B hardly affects growth parameters. In contrast with outdoor studies on higher plants, soluble UV-B absorbing compounds in bryophytes are typically not induced by enhanced levels of UV-B radiation. A few studies have demonstrated that UV-B radiation can influence plant morphology, photosynthetic capacity, photosynthetic pigments or levels of DNA damage. However, there is only a limited number of outdoor studies presented in the literature. More additional, especially long-term, experiments are needed to provide better data for statistical meta-analyses. A mini UV-B supplementation system is described, especially designed to study effects of UV-B radiation at remote field locations under harsh conditions, and which is therefore suited to perform long-term studies in the Arctic or Antarctic. The first results are presented from a long-term UV-B supplementation experiment at Signy Island in the Maritime Antarctic.

Accumulation of DNA damage in Antarctic mosses: correlations with ultraviolet‐B radiation, temperature and turf water content vary among species

“…While UV‐B‐screening compounds and structures are a feature of the epidermal layers of many higher plants, the simple structure of bryophytes, particularly the lack of epidermal layers, was assumed to render them particularly vulnerable to UV‐B damage (Gwynn‐Jones et al , 1999). However, recent work suggests that some bryophyte species have high resilience to UV‐B radiation (Lud et al , 2002; Newsham et al , 2002; Newsham, 2003; Boelen et al , 2006; Dunn & Robinson, 2006; Clarke & Robinson, 2008).…”

Cell compartmentation of ultraviolet‐absorbing compounds: An underexplored tool related to bryophyte ecology, phylogeny and evolution

“…This lack of influence was expected for attributes a priori neutral for UVACs, such as size, life‐form, sex, reaction‐pH (R) or nitrogen (N), but not for attributes presumably influencing the light levels (and thus, the UV levels) received by the bryophytes, such as orientation, light (L), exposure index or biogeographic origin. Nevertheless, it must be taken into account that a UV increase has sometimes resulted in a concomitant UVACs increase in bryophytes under field conditions (Newsham, ; Newsham, Geissler, Nicolson, Peat, & Lewis‐Smith, ; Newsham & Robinson, ; Núñez‐Olivera, Otero, Tomás, Fabón, & Martínez‐Abaigar, ; Núñez‐Olivera, Otero, Tomás, & Martínez‐Abaigar, ), though this is not always the case (Arróniz‐Crespo et al., ; Boelen, De Boer, De Bakker, & Rozema, ; Núñez‐Olivera et al., ; Robinson, Turnbull, & Lovelock, ; Snell, Convey, & Newsham, ). The non‐influence of light‐related attributes on UVACs that was revealed in our study, together with the contrasting responses of UVACs to UV radiation found in the literature, suggest that UVACs may be notably constitutive for each bryophyte species or lineage, and not especially inducible by the environment (Martínez‐Abaigar & Núñez‐Olivera, ; Robinson & Waterman, ).…”

Evolutionary conservation of structure and function of the UVR8 photoreceptor from the liverwort Marchantia polymorpha and the moss Physcomitrella patens

“…Thus, our aim was to study the structure and function of UVR8 from the moss P. patens and the liverwort Marchantia polymorpha . The rationale for studying UVR8 in these two species is that: they represent two early diverging evolutionary lineages of land plants that were important for land colonisation, a process in which UV‐B radiation could play a role as an evolutionary pressure; liverworts and mosses may represent two different modalities of bryophytes in their responses to UV‐B radiation (Fabón et al ., ); responses of bryophytes to UV‐B radiation depend on the species used (Boelen et al ., ; Martínez‐Abaigar & Núñez‐Olivera, ), so that using two different species can allow, to a certain extent, assessment of the variability of UVR8 behaviour in bryophytes; and the two species studied are increasingly important as model species in plant biology.…”