Diversity of winter photoinhibitory responses: a case study in co‐occurring lichens, mosses, herbs and woody plants from subalpine environments

Abstract

Winter evergreens living in mountainous areas have to withstand a harsh combination of high light levels and low temperatures in wintertime. In response, evergreens can activate a photoprotective process that consists of the downregulation of photosynthetic efficiency, referred to as winter photoinhibition (WPI). WPI has been studied mainly in woody evergreens and crops even when, in many instances, other functional groups such as lichens or bryophytes dominate in alpine and boreal habitats. Thus, we aimed to (1) assess the occurrence of WPI within overwintering evergreens comprising woody species, herbs, mosses and lichens, (2) compare the recovery kinetics among those groups and (3) clarify the role of thylakoid proteins and pigments in both processes: WPI and recovery. With this aim, WPI was analyzed in 50 species in the field and recovery kineticcs were studied in one model species from each functional group. Results showed that high levels of WPI are much more frequent among woody plants than in any other group, but are also present in some herbs, lichens and mosses. Winter conditions almost always led to the de-epoxidation of the xanthophyll cycle. Nevertheless, changes in the de-epoxidation level were not associated with the activation/deactivation of WPI in the field and did not match changes in photochemical efficiency during recovery treatments. Seasonal changes in thylakoid proteins [mainly D1 (photosystem II core complex protein) and PsbS (essential protein for thermal dissipation)] were dependent on the functional group. The results highlight the diversity of physiological solutions and suggest a physical-mechanical reason for the more conservative strategy of woody species compared with other groups.

Born to revive: molecular and physiological mechanisms of double tolerance in a paleotropical and resurrection plant

“…S2). This is also in agreement with the general behaviour observed in perennial herbs in comparison with conifers (Míguez et al , 2015, 2017). Interestingly, this downregulation of F v / F m was apparently related to an acclimation process inside the chloroplast mediated by changes in the thylakoid lipid composition and in the carotenoid content of the xanthophyll cycle (Fig.…”

“…This energy dissipation is typically segregated into two components distinguished by the speed of their reversibility upon exposure to optimal conditions (high temperature and darkness). Thus, the dynamic component is reversible within the duration of minutes to hours, while the sustained (sometimes referred to in the literature as ‘chronic’) component reverses much more slowly (Verhoeven, 2014; Míguez et al , 2017). In agreement with data obtained with garden plants of R. myconi acclimated to winter (subzero temperatures) in the Alps (Fernández‐Marín et al , 2018b), our results show a larger dynamic component and a small sustained WPI component under natural field conditions (Fig.…”

“…S2). Following Míguez et al (2017) with slight modifications, we estimated the sustained WPI as the downregulation in maximum F v / F m that was maintained even after 12 h of incubation at 20°C in the dark.…”

Photoprotective Strategies of Mediterranean Plants in Relation to Morphological Traits and Natural Environmental Pressure: A Meta-Analytical Approach

“…This process has been characterized in detail in boreal conifers and alpine evergreens (Verhoeven, 2014; Míguez et al, 2017) involving profound change in the organization of photosynthetic apparatus. The overnight retention of AZ/VAZ is usually concurrent with a proportional decrease of photochemical efficiency (measured as Fv/Fm) (Demmig-Adams et al, 2006), also known as “winter photoinhibition.” In Mediterranean evergreens, the existence of an inverse relationship between AZ/VAZ and Fv/Fm, notably in winter (Figure 5B), suggests that Mediterranean evergreens employ the same mechanism of down-regulation of photochemical efficiency as boreal and alpine evergreens.…”

Defective photosynthetic adaptation mechanism in winter restricts the introduction of overwintering plant to high latitudes

“…These changes were accompanied by significant alterations in chloroplast ultrastructure resulting in a substantial loss of thylakoid grana during winter (Yokono et al ., 2008; Maslova et al ., 2009; Silva-Cancino et al ., 2012). Both PSI and PSI photochemical activities decreased (Ottander et al ., 1995; Ivanov et al ., 2001; 2002; Ensminger et al ., 2004; Robakowski et al ., 2005) and this was attributed to degradation of a number of PSII and PSI related proteins during winter (Ottander et al ., 1995; Ebbert et al ., 2005; Verhoeven et al ., 2009; Míguez et al ., 2017). However, the PSII photoinhibition was more pronounced than that of PSI during winter (Ivanov et al ., 2001; 2006).…”