FUNCPTOXTHELL

The role and functioning of the PTOX in stress tolerance in extremophile Thellungiella halophila

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 Obiettivo del progetto (Objective)

'Climate is the great factor that mankind has not yet managed to control. Drought, flood, high temperature, salinity and air pollution are among the major factors limiting crop productivity. The effects of various environmental stresses in plants are known to be mediated, at least partially, by an enhanced generation of reactive oxygen species (ROS). The main site of ROS production in stressed plant is chloroplast, exposed to excessive energy absorbed. ROS are highly reactive and can cause widespread damage to membranes, proteins and DNA. To prevent such damages there are a number of enzymatic processes in chloroplast to scavenge ROS. Unfortunately they are highly energetically demanding, requiring the synthesis of high concentrations of the low-molecular weight antioxidants and antioxidative enzymes. Therefore, to place less of a metabolic burden on plants, the effective regulation of the photosynthetic electron transport is crucial to avoid enhanced ROS formation under stress conditions. In Researcher recent studies the effects of short-term salt stress on the regulation of photosynthetic electron transport in Arabidopsis thaliana and its salt-tolerant close relative Thellungiella halophila has been examined. Results obtained provide the evidence for the plastid terminal oxidase (PTOX) to act as a significant electron sink from photosystem II (PSII). In salt-stressed Thellungiella, PTOX-dependent electron transport accounts for up to 30% of total linear electron flow, suggesting a major role for this pathway in protecting plants from photodamage. The aim of present project is to investigate the role and functioning of PTOX in Thellungiella halophila with the focus on the regulatory mechanism and factors that allow it to act as a sink for electron transport from PSII. Additionally, we will investigate whether Thellungiella PTOX activity can be transferred into another species and whether this has the potential to increase stress tolerance.'

Introduzione (Teaser)

New research into an enzyme in the stress tolerant Thelungiella halophila plant has provided insights that could help scientists engineer the same resilience in food crops.

Descrizione progetto (Article)

Stresses such as drought, high salt and high temperatures cause cellular damage and death in plants via the increased production of reactive oxygen species (ROS). An enzyme in T. halophila, plastid terminal oxidase (PTOX), has recently been identified as being able to 'mop up' ROS before they can damage the plant. Scientists refer to this kind of enzyme as an electron sink.

An EU-funded research project called 'The role and functioning of the PTOX in stress tolerance in extremophile Thelungiella halophila' (FUNCPTOXTHELL) was established to investigate this enzyme in more detail. In particular, the researchers aimed to use PTOX to confer stress tolerance to other plants.

They investigated the regulation of PTOX in the cell to find out how it works as an electron sink. Project plans included engineering PTOX into a different plant species to investigate whether it would improve the stress tolerance in other plants, such as crops.

On its own, PTOX could not improve stress tolerance in other plants, suggesting that other factors are involved. Further work showed that PTOX interacted with several proteins involved in photosynthesis, and that these were found in the same parts of the cell when the plants were exposed to stress. Another important finding was that the function of PTOX differed in response to different types of stress.

PTOX is known to be a key enzyme in stress tolerance in T. halophila, and this research expanded knowledge of the underlying mechanisms. The research will also form a substantial information base for engineering other stress-tolerant plants.