Quantification of the mechanisms of light tolerance that determine growth and productivity in plants and algae.

This proposal addresses the rapid adaptation of plants and algae to frequent changes in the light environment: non-photochemical quenching (NPQ). The molecular basis of NPQ and the assessment of NPQ effectiveness and high light tolerance in photosynthetic organisms are the focus of this proposal. The mechanism behind the adaptive reorganisation of the photosynthetic apparatus in response to high light intensities will be reproduced in membranes selectively devoid of its components and studied using electron microscopy, spectroscopy and biochemistry approaches. The role of specific proteins PsbS and Lhcx in the process will be addressed. A recently-developed novel method will be applied to determine effectiveness of NPQ and high light tolerance of plants and algae - a so-called pNPQ technology. This knowledge is important for understanding the patterns of the evolution of photosynthetic organisms in changing environments, allowing for the prediction of the impact of the climate change upon our planet's plant and algal communities. The proposal is timely since the PI has discovered the PsbS protein interaction patterns with the components of the photosynthetic apparatus, the economic nature of NPQ and visualised specific clustering of the light-collecting proteins (LHCII) in the photosynthetic membrane. Further, the recent paper of Niyogi's and Long's laboratories (https://www.ncbi.nlm.nih.gov/pubmed/27856901) benefited from the use of pNPQ-based technology that helped to develop better performing crop plants just by making their NPQ respond more quickly to light fluctuations. In addition, the company Optisciences (USA) has utilised the pNPQ methodology in their revolutionary plant monitoring fluorimeter PSP32 (http://www.optisci.com/psp32.html) that is indispensable for monitoring plant light tolerance in the field. Hence, the further impact of the current proposal on research dealing with crop improvement via enhancement of energy-harvesting or light-endurance properties is expected.

This proposal focuses on the localisation, protective effectiveness and impact on productivity of the photosynthetic organisms of the photoprotective energy dissipation, NPQ. The site of NPQ (major vs minor LHCII antenna) will be established since the PI possesses a mutant that completely lacks the minor LHCII antenna complexes, CP24,26 and 29. This is a unique opportunity to end the long lasting debate about the role of the minor PSII light harvesting antenna in NPQ. The role of specific proteins related to the NPQ process such as PsbS in plants and Lhcsx diatom algae will be addressed. The hypothesis of CONVERGENT EVOLUTION OF NPQ function in these two classes of photosynthetic organisms will be tested. Here we will test if Lhcx is as PsbS not a pigment binding but proton sensing protein that triggers conformational changes in antenna leading to the establishment of the protective state. This part of the proposal is timely since recently the PI has discovered the PsbS protein interaction patterns with the components of the photosynthetic apparatus, the economic nature of NPQ and visualised specific clustering of the light-collecting proteins (LHCII) in the membrane. The pNPQ technology will be used to assess plant and algal capacity to protect themselves in context with the assessment of RCII repair cycle. Hence, the role of NPQ and repair processes in determining overall tolerance of the photosynthetic organisms will be established. High light and drought tolerant plant species will be studied using the new technology in order to establish which protective strategy, NPQ or D1 stability/repair process determine their resilience. Finally, the conditions when photodamage or sustained NPQ undermine growth and productivity of the photosynthetic organisms will be investigated in order to understand what molecular factors promote formation of sustained protective NPQ or strong photodamage and find their detrimental or beneficial role for growth and productivity.

Who will benefit from this research? How will they benefit from this research?
1. The Environment
The project will benefit the environment in several ways. Firstly, any increase in the productivity of UK agriculture will allow the home-grown share of the fruits and vegetables market to increase, thus reducing the amount imported from overseas. A decrease in fruit and vegetable imports will reduce the carbon footprint of the consumer by reducing food miles. The project also promises to reduce the necessary artificial light energy input into UK glasshouses, again reducing the carbon footprint. In addition, in the very near future, there will be a strongly increasing demand for sustainable energy for our society. The sun is the far biggest source of energy, and photosynthetic organisms in both land and aquatic environments are the foundations of a bio-based economy. Increases in photosynthetic productivity can benefit UK society by increasing the amount of biomass available for conversion into biofuels and increasing food security through higher crop yields.
2. The UK Agriculture Sector
The principle end users of this research will be in the commercial sectors associated with crops, including biofuels. The maximum predicted profit from the improvement of NPQ dynamics in the field for all UK crops could potentially reach £300M. The PI together Professor Conrad Mullineaux (QMUL) was a recipient of a grant from the Carbon Trust on Algal Biofuels Challenge (ABC) to explore certain marine algae for the use in the generation of biodiesel. It is possible that identified NPQ mutants will also be useful for increasing algal photosynthetic productivity especially where controlled environmental conditions are used in biorectors etc.
3. The UK Economy
In addition to increased profits from enhanced crop plant productivity the UK economy will also benefit from the project by providing training and experience for UK scientists and technicians in a multidisciplinary array of microscopic, spectroscopic, biochemical and other practical techniques. The skills they acquire will enable them to think of innovative, cross-discipline solutions to the crucial biological and environmental problems of the present and future, and to play a part in developing a successful bio-based economy.
4. Agrobiotech companies such as Syngenta
The project will benefit agrobiotechnology companies at home and abroad, who will be interested in genes identified by the project as targets for increased photosynthetic productivity. Potentially these companies can create mutants currently only available in Arabidopsis for crop plants and sell these under license to the domestic and global agriculture sector.
What will be done to ensure that they benefit from this research?
Dissemination of results: Publications in peer-reviewed international journals; Oral and poster contributions at international scientific meetings and workshops; the project will be described on the PI's website; (http://webspace.qmul.ac.uk/aruban); publicity of important finding via press releases from QMUL. We will also actively engage with a range of agrobiotech companies providing them with presentations of our findings, opening a dialogue on the future application of our research to crop plants.
Training: The training opportunities provided by this project will be greatly augmented by the participation of the PI in the SE2B ('Solar Energy to Biomass') Marie Curie training Network. SE2B brings together 9 top institutes from various disciplines working on the elementary regulation mechanisms in oxygenic photosynthesis, as well as academic groups and commercial enterprises working on new methodologies suitable for industrial and commercial exploitation of biosolar energy.