Abstract
Desiccation tolerance and longevity of plant propagules in the dry state have significant implications for biotechnological applications. In this study fern spores were used as a unicellular model to characterize some of the mechanisms of ageing during dry storage of plant propagules (at relative humidity ca. 15%). More specifically, we compared the potential relationships among indicators of photo-oxidative stress and spore viability during dry storage between green (chlorophyllous) spores of Todea barbara and non-green spores of Christella dentata. Green spores stored under the light aged faster than those stored in the dark, and faster than light- and dark-stored non-green spores of C. dentata. This rapid ageing in light-stored green spores was associated with significantly lower antioxidant activity (relative to time zero and dark-stored spores) during storage, and a burst of hydrogen peroxide during the latter stages of storage, which was not a feature of dark-stored spores. We attribute these signs of enhanced oxidative-stress mediated ageing in light-stored spores to photo-oxidative processes, similar to those described in other homoiochlorophyllous organisms. Additionally, high antioxidant activity and low levels of reactive oxygen species in green spores compared with non-green spores suggests differing mechanisms of coping with life in the dry state.
Highlights
The study of desiccation tolerance and longevity in the dry state in plant propagules is important to understand the success of plants on terrestrial Earth and the laws governing life on it, and has implications on biotechnological applications in diverse fields such as medicine, crop improvement, and genetic diversity preservation (Leprince and Buitink 2010)
Longevity in the glassy state is life form and species dependent (e.g. Walters et al 2005; Hoekstra 2005; Ballesteros et al 2017), and mechanisms of ageing in the glassy state are often associated with oxidative stress (Walters et al 2010) little is known about how these mechanisms may differ with life form and propagule post-harvest physiology
While mechanisms of desiccation tolerance and life in the dry state have received much attention in lichens, bryophytes, resurrection plants and seeds, little is known for fern spores
Summary
The study of desiccation tolerance and longevity in the dry state in plant propagules is important to understand the success of plants on terrestrial Earth and the laws governing life on it, and has implications on biotechnological applications in diverse fields such as medicine, crop improvement, and genetic diversity preservation (Leprince and Buitink 2010). It resembles a solid (Leprince and Buitink 2015; Walters 2015). This change from fluid to solid is known as vitrification glass transition from solid to fluid and the resulting (amorphous) solid is often referred to as a glass. Desiccation tolerant organisms survive the compressive forces and cell volume reduction before glasses are formed (Leprince and Buitink 2015; Walters 2015; Ballesteros et al 2017), and after vitrification they ideally should survive a relatively long time in the glassy state (e.g. Walters et al 2005; Ballesteros et al 2017). Longevity in the glassy state is life form and species dependent (e.g. Walters et al 2005; Hoekstra 2005; Ballesteros et al 2017), and mechanisms of ageing in the glassy state are often associated with oxidative stress (Walters et al 2010) little is known about how these mechanisms may differ with life form and propagule post-harvest physiology
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