Activation of violaxanthin cycle in darkness is a common response to different abiotic stresses: a case study in Pelvetia canaliculata

Abstract

BackgroundIn the violaxanthin (V) cycle, V is de-epoxidized to zeaxanthin (Z) when strong light or light combined with other stressors lead to an overexcitation of photosystems. However, plants can also suffer stress in darkness and recent reports have shown that dehydration triggers V-de-epoxidation in the absence of light. In this study, we used the highly stress-tolerant brown alga Pelvetia canaliculata as a model organism, due to its lack of lutein and its non-photochemical quenching independent of the transthylakoidal-ΔpH, to study the triggering of the V-cycle in darkness induced by abiotic stressors.ResultsWe have shown that besides desiccation, other factors such as immersion, anoxia and high temperature also induced V-de-epoxidation in darkness. This process was reversible once the treatments had ceased (with the exception of heat, which caused lethal damage). Irrespective of the stressor applied, the resulting de-epoxidised xanthophylls correlated with a decrease in Fv/Fm, suggesting a common function in the down-regulation of photosynthetical efficiency. The implication of the redox-state of the plastoquinone-pool and of the differential activity of V-cycle enzymes on V-de-epoxidation in darkness was also examined. Current results suggest that both violaxanthin de-epoxidase (VDE) and zeaxanthin-epoxidase (ZE) have a basal constitutive activity even in darkness, being ZE inhibited under stress. This inhibition leads to Z accumulation.ConclusionThis study demonstrates that V-cycle activity is triggered by several abiotic stressors even when they occur in an absolute absence of light, leading to a decrease in Fv/Fm. This finding provides new insights into an understanding of the regulation mechanism of the V-cycle and of its ecophysiological roles.

Application of heat stress in situ demonstrates a protective role of irradiation on photosynthetic performance in alpine plants

“…However, it is interesting to note that Fernández‐Marín et al . (, ) also found that the enzyme violaxanthin de‐epoxidase was activated in the lichen, Lobularia pulmonaria , and in the brown seaweed, Pelvetia canaliculata , in the dark in response to desiccation or high temperature. Furthermore, violaxanthin de‐epoxidation was also induced in response to heat stress at very low irradiation (12 μ mol photons m −1 ·s −1 ) in wheat seedlings (Ilik et al .…”

First evidence of freezing tolerance in a resurrection plant: insights into molecular mobility and zeaxanthin synthesis in the dark

“…These possible alterations in the chloroplast may include changes in the lipid composition of the thylakoids, in the luminal pH (i.e. by chlororespiration) and/or in the redox state of luminal proteins (Fernández‐Marín et al , , Gasulla et al , Kang and Wang ). Our results demonstrated that significant reductions in F v / F m consistently occurred in response to freezing R. myconi leaves in darkness, although the extent of the reduction of F v / F m was highly variable (Fig.…”

Diadinoxanthin de‐epoxidation as important factor in the short‐term stabilization of diatom photosynthetic membranes exposed to different temperatures

“…It is commonly known that Ddx, as well as Vx, de‐epoxidation depends on high light illumination. However, Fernández‐Marín, Míguez, Becerril, and García‐Plazaola () have shown that Vx de‐epoxidation also occurs in darkness. In Pelvetia canaliculata , a highly stress‐tolerant brown alga, de‐epoxidation was induced by high temperature and other factors such as immersion, anoxia, and dehydration.…”