Desiccation tolerant plants as model systems to study redox regulation of protein thiols

Abstract

While the majority of plants and animals succumb to water loss, desiccation tolerant organisms can lose almost all of their intracellular water and revive upon rehydration. Only about 300 'resurrection' angiosperms and very few animals are desiccation tolerant. By contrast, many bryophytes and most lichens are desiccation tolerant and so are the seeds and pollen grains of most flowering plants. The current literature reveals that the extreme fluctuations in water content experienced by desiccation tolerant organisms are accompanied by equally extreme changes in cellular redox state. Strongly oxidizing conditions upon desiccation can cause irreversible oxidation of free cysteine residues of proteins, which can change protein structure and function, and contribute to protein denaturation. It appears likely that reversible formation of disulphide bonds, in particular through protein glutathionylation, contributes to the set of protection mechanisms that confer desiccation tolerance. Upon rehydration, de-glutathionylation can be catalyzed by glutaredoxins (GRXs) and protein disulphide bonds can be reduced through NADPH-dependent thioredoxins (TRXs). Due to their ability to survive severe oxidative stress, desiccation tolerant plants and seeds are excellent models to study protein redox regulation, which may provide tools for enhancing tolerance to drought and more generally, to oxidative stress, in crops.

Changes in the reduction state of ascorbate and glutathione, protein oxidation and hydrolysis leading to the development of dehydration intolerance in Triticum aestivum L. seedlings

“…A high GSH/GSSG ratio was maintained both in dehydration sensitive and tolerant seedlings because of the increased concentration of GSH and the activity of glutathione reductase. The maintenance of a high GSH/GSSG ratio and activity of glutathione reductase under drought conditions was previously observed in wheat, tomato and rice (Colville and Kranner 2010). The ratio of AsA/DHA increased in sensitive seedlings.…”

“…A plant's ability to withstand severe dehydration is limited to mature seeds and pollen of higher plants and to groups of vascular angiosperm plants (Colville and Kranner 2010). Wheat (Triticum aestivum L.) seedlings tolerate a high water deficit up to the 5th day of germination, but the appearance of the first leaf from the coleoptile coincided with a susceptibility to dehydration (Miazek et al 2001).…”

Editorial: special issue GROW “plant desiccation stress”

“…Gaff , 1977 and that the seeds of some species are desiccation sensitive (DS), these termed ''recalcitrant'' (see e.g. Chin and Roberts 1980). Since those early reports, research on vegetative DT and seed DS has steadily grown, undoubtedly driven in part by the potential applied benefits.…”

“…Typically such studies pose specific research questions and are conducted using discipline specific approaches on a single species, but often reflect some common questions and strategies associated with research into desiccation tolerance. Papers within this issue report on stresses associated with water deficit, such as the mechanical stress of plasmolysis (Koster et al 2010), oxidative stresses, including those associated with light (Aidar et al 2010;Proctor 2010;Kamies et al 2010;Colville and Kranner 2010) and the protective responses generated in response to those stresses, or take a more global approach of searching for genes and gene products up regulated in response to stress (Abdalla et al 2010). In addition to furthering our understanding of stresses and associated protection these works add important information to the field.…”

“…This novel approach is likely to open the door for many future studies on root tissues of such plants. Colville and Kranner (2010) provide an excellent review of responses of desiccation tolerant plants and seeds to oxidative stress, showing that such organisms are robust models for the study of protein redox regulation. Abdalla et al (2010) have identified nuclear proteins significantly up-regulated during drying of the resurrection plant Xerophyta viscosa, these data confirming that DT is indeed characterised and controlled by a multiple gene response.…”