The Fate of Excitation Energy in Photoinhibited Chloroplasts

Project Information

xFATE

Grant agreement ID: 799083

DOI

10.3030/799083

Project closed

EC signature date 27 February 2018

Start date 1 March 2018

End date 29 February 2020

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 165 598,80

EU contribution

€ 165 598,80

Coordinated by

STICHTING VU
Netherlands

Periodic Reporting for period 1 - xFATE (The Fate of Excitation Energy in Photoinhibited Chloroplasts)

Reporting period: 2018-03-01 to 2020-02-29

Summary of the context and overall objectives of the project

It is common, textbook knowledge that plants use light to grow. The process of photosynthesis relies on capturing light by pigment-binding proteins located in the chloroplast. Then, a series of electron transfer reactions follows, allowing photosynthetic organisms to reduce atmospheric carbon in CO2. However, sunlight is also constantly damaging plants’ photosynthetic apparatus. In particular, Photosystem II (PSII), the multimeric light-driven enzyme capable of water oxidation in the first step of photosynthetic electron transfer, very often becomes damaged and requires disassembly and repair. The impairment of PSII due to light is called photoinhibition. During the course of this Marie Skłodowska-Curie fellowship, we investigated first steps of photodamage process to better understand the Janus-faced relationship between plants and light. Comprehension of the initial stages of photoinhibition is crucial because it is one of the main processes that limits the growth of plants in the natural conditions and as such, possesses a large energetic cost for these organisms.
In particular, presence of light prompts plants to develop or trigger mechanisms allowing them to dissipate some of the excess absorbed energy, termed non-photochemical quenching (NPQ). We aimed at describing the location of this quenching after photoinhibition was triggered in living organisms, and then providing full characteristics of this process.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the span of the fellowship, we combined several physicochemical approaches best suited to studies of the photoinhibition-related quenching. We used primarily biophysical (spectroscopic) methods to study the behaviour of fluorescence in living algae. Because quenching directly competes with fluorescence emission from the photosynthetic pigments, fluorescence spectroscopy is easy mean to probe quenching capacity. We further integrated biophysics with genetic approaches, i.e. mutants of the algae with genes coding for proteins involved in photoinhibition and PSII repair, to disentangle some of the processes we observed. Finally, biochemical methods and isolation of proteins from the plants allowed us to pinpoint the location of the quencher and its molecular nature.
Dissemination of the results of our research occurred through the usual means, including press releases and open-access publications, although we focused on an emerging medium for science communication – the microblogging platform twitter. You can read about the results of research conducted throughout the timespan of the fellowship by following the account @wjnawrocki.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

As a result of the research we conducted, we discovered the location of the quencher within plant chloroplasts. We further stabilised the entity which performs the quenching using genetic-based methods. Finally, we were able to successfully isolate it, and we continue to characterise it by investigating a potential heterogeneity in the preparation. The research conducted during the fellowship allowed a considerable advancement in understanding of the biophysics of photoinhibition and the cycle of PSII degradation and repair.
We would like to highlight that the socio-economic impact of research exists by the sole fact of increasing knowledge about the world that surrounds us, and that possible applications of science only come in long term. Even if our studies of photoinhibition-related quenching will permit in long-term to develop strategies of more efficient photoprotection in crops, or increased rate of PSII repair, a crucial prerogative is the complete understanding of the complex and intricate system we are dealing with in our everyday lives.

graphican summary of the project - photoinhibition of Photosystem II cycle