Protection of the photosynthetic apparatus against dehydration stress in the resurrection plant Craterostigma pumilum

Abstract

The group of homoiochlorophyllous resurrection plants evolved the unique capability to survive severe drought stress without dismantling the photosynthetic machinery. This implies that they developed efficient strategies to protect the leaves from reactive oxygen species (ROS) generated by photosynthetic side reactions. These strategies, however, are poorly understood. Here, we performed a detailed study of the photosynthetic machinery in the homoiochlorophyllous resurrection plant Craterostigma pumilum during dehydration and upon recovery from desiccation. During dehydration and rehydration, C. pumilum deactivates and activates partial components of the photosynthetic machinery in a specific order, allowing for coordinated shutdown and subsequent reinstatement of photosynthesis. Early responses to dehydration are the closure of stomata and activation of electron transfer to oxygen accompanied by inactivation of the cytochrome b6 f complex leading to attenuation of the photosynthetic linear electron flux (LEF). The decline in LEF is paralleled by a gradual increase in cyclic electron transport to maintain ATP production. At low water contents, inactivation and supramolecular reorganization of photosystem II becomes apparent, accompanied by functional detachment of light-harvesting complexes and interrupted access to plastoquinone. This well-ordered sequence of alterations in the photosynthetic thylakoid membranes helps prepare the plant for the desiccated state and minimize ROS production.

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

“…Resurrection species decrease carbon assimilation rate to undetectable levels when WC drops below 0.2 g H 2 O g −1 DW (Georgieva et al , 2007; Gashi et al , 2013; Tan et al , 2017) and carbon fixation stops earlier than photochemistry upon drying (Schwab et al , 1989; Georgieva et al , 2007; Zia et al , 2016). Accordingly, naturally dry R. myconi plants showed WC below 0.1 g H 2 O g −1 DW, corresponding to F v / F m values also below 0.1 and with remarkably high AZ : VAZ values (Table 1; Figs 2, S2, S3).…”

Plant Desiccation Tolerance and its Regulation in the Foliage of Resurrection “Flowering-Plant” Species

“…Protection against the damaging effects of desiccation is essential to enable the vegetative parts of resurrection species to remain viable and intact in their typically dry, high light and otherwise hostile environments, often for extended periods of time [11,140]. Most of the initial reports dealing with the molecular genetics of desiccation tolerance involved the use of a range of differential cDNA screening procedures to identify genes with altered (mainly increasing, though some decreasing) transcript abundance in RNA extracted from leaf tissues at various stages in the dehydration process.…”

Orthodox Seeds and Resurrection Plants: Two of a Kind?

“…1), such as B. hygrometrica, Craterostigma spp., H. rhodopensis, Myrothamnus flabellifolius, S. stapfianus, and Tripogon loliiformis, degrade only a small amount of Chl during dehydration (Farrant, 2000;Georgieva et al, 2007;Blomstedt et al, 2010;Mitra et al, 2013;Sárvári et al, 2014;Williams et al, 2015). These plants retain macro-level thylakoid structure, deactivating and activating partial components of the photosynthetic machinery in a specific order, which allows for coordinated shutdown and subsequent reinstatement of photosynthesis during drying and rehydration, respectively (Charuvi et al, 2015;Zia et al, 2016). In HDT, the leaf area exposed to light (for example) is reduced via leaf curling, the presence of reflective hairs, and anthocyanin accumulation ( Fig.…”