Unravelling the roles of desiccation-induced xanthophyll cycle activity in darkness: a case study in Lobaria pulmonaria

Abstract

Desiccation-tolerance ability in photosynthetic organisms is largely based on a battery of photoprotective mechanisms. Xanthophyll cycle operation induced by desiccation in the absence of light has been previously proven in the desiccation-tolerant fern Ceterach officinarum. To understand the physiological function of xanthophyll cycle induction in darkness and its implication in the desiccation tolerance in more detail, we studied its triggering factors and its photochemical effects in the lichen Lobaria pulmonaria. We found that both the drying rate and the degree of desiccation play a crucial role in the violaxanthin de-epoxidase activation. De-epoxidation of violaxanthin to zeaxanthin (Z) occurs when the tissue has lost most of its water and only after slow dehydration, suggesting that a minimum period of time is required for the enzyme activity induction. Fluorescence analysis showed that Z, synthesised during tissue dehydration in the absence of light, prevents photoinhibition when rewatered tissues are illuminated. This is probably due to Z implication in both non-photochemical quenching and/or antioxidative responses.

Dehydration-mediated activation of the xanthophyll cycle in darkness: is it related to desiccation tolerance?

“…This idea is supported by the fact that it is a common response to dehydration in all desiccation-tolerant species belonging to different lineages analysed so far (Fig. 1b, d, f, h, j, l) (see also Fernandez-Marin et al 2010).…”

“…(Fernandez-Marin et al 2010). Although Z formation has also been reported in dehydrating leaf discs of several vascular plants (Fernández-Marín et al 2009), the extent of this trait across the plant kingdom and its relationship to desiccation tolerance are unclear.…”

Effects of controlled oxidative stress and uncouplers on primary photosynthetic processes in vegetative cells of Antarctic alga Zygnema sp.

“…Such increase relates to J and I chlorophyll fluorescence levels that are attributed to energy transfer from LHCs to RCs and a primary acceptor. Similar results were obtained for DTTtreated algal lichen Lobaria pulmonaria by Fernández-Marín et al (2010) who reported DTT-induced increase in I and J chlorophyll fluorescence level in dried and subsequently hydrated thalli. Their explanation of the chlorophyll fluorescence increase relates to an integrity and function of the photosynthetic apparatus during desiccation and a potential role of lack zeaxanthin in this process.…”

Warming reduces the growth and diversity of biological soil crusts in a semi-arid environment: implications for ecosystem structure and functioning

“…This mechanism has already been demonstrated in the lichen Lobaria pulmonaria (L.) Hoffm. [86], and could explain declines in lichen cover with warming, as desiccation should occur much faster because of the temperature increase in this treatment (see the electronic supplementary material, appendix S5). Mosses usually show more structural complexity than lichens [83,87], and this may allow mosses to have quicker responses to desiccation [88].…”

“…In this context, recent studies [85,86] suggest that if desiccation occurs faster than in normal conditions, photoprotective mechanisms do not work properly, and, as a consequence, structural damages are likely to occur. This mechanism has already been demonstrated in the lichen Lobaria pulmonaria (L.) Hoffm.…”