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Increasing plant stress tolerance by unravelling and exploiting the mechanism of the photosynthetic NDH complex

Project description

One of the greatest challenges facing the developing world is increasing population, with no corresponding increase in available agricultural land for food and biofuel crops. It is therefore becoming paramount to find ways of growing crops and other useful plants on marginal land, and in stressful conditions (high salinity, drought, etc.). Primary productivity and crop yield are dependent on efficient photosynthesis. Modern cyanobacteria contain several stress resistance mechanisms that have been lost during the evolution of higher plant chloroplasts, and using synthetic biology to reintroduce these genes to improve stress tolerance is therefore timely. One example is the small electron transfer protein flavodoxin (Fld), which confers tolerance to a broad range of stresses when expressed in plants. The mechanism by which Fld confers stress tolerance remains unknown, and one possibility that has not been addressed so far is through electron donation to the chloroplast NAD(P)H dehydrogenase-like complex (NDH). Loss-of-function NDH mutants display altered leaf levels of reactive oxygen species and delayed senescence. Although many NDH subunits have been identified in genetic studies and increase in NDH abundance dramatically influences electron transport, very little is understood about the function of NDH, and no biophysical studies are reported.

Our goal is to define the function of genes that enhance plant stress tolerance by combining expertise in biophysics, biochemistry and genetics. A key milestone in achieving this goal lies in understanding the function and mechanism of the NDH complex in both cyanobacteria and higher plants. In this project, we will: (1) identify the specific electron donors to the NDH-like complex and characterize these interactions, establishing the correct partner proteins for optimal NDH function (2) characterize the energy landscape within the NDH, using native NDH and custom made mutant complexes, (3) introduce genes that promise to enhance stress tolerance, first to the model plant tobacco, and then to commercially important crops (in collaboration with Prof. Nestor Carrillo, Rosario, Argentina).

Research environment

The PhD student will join two vibrant and well-funded growing research groups that are located on the same campus and work in a collaborative, international and multi-disciplinary research environment. The student will receive training in a number of biochemical and biophysical techniques as well as genetics, and will be given the opportunity to attend international conferences. Moreover, the Roessler laboratory will host a major international EPR conference in 2018 that the candidate would have the opportunity to be involved in. Find out more about the work of the Roessler group and Hanke group.

Queen Mary University of London (QMUL)

As a member of the prestigious Russell group, QMUL is one of UK’s leading research-focused higher education institutions, where multidisciplinary research is carried out at the highest level. The university is unique in London by providing a completely integrated residential campus. All researchers are part of the QMUL Doctoral College, which provides high quality training in transferable key skills and free English language courses are also available through the Queen Mary Language Centre.

The School of Biological and Chemical Sciences at QMUL is a highly interdisciplinary environment and home to state-of-the-art facilities, including EPR spectrometers at multiple microwave frequencies, high field NMR and mass spectrometers. The School holds an Athena SWAN Silver Award and is committed to supporting equality and diversity for all staff and students.

Eligibility

Outstanding students with, or expecting to receive, at least an upper-second class honours degree (or equivalent) and preferably as Masters degree in chemistry, biochemistry or a related subject. International students are required to provide evidence of their proficiency in English language skills.

How to apply

Candidates should e-mail Dr Roessler or Dr Hanke with cover letter and CV, explaining how they intend to fund their project. Informal enquiries about the project are welcome.

Funding notes

Applicants wishing to apply for PhD funding through Ciência sem Fronteiras, CONACT, the China Scholarship Council, the Pakistani Higher Education Commission or the Islamic Development Bank are welcomed. The project is also open to applicants who can self-fund, however, these applicants should be able to demonstrate that they can cover the cost of living expenses and tuition fees for a minimum of 3.5 years.

References

1 Peltier P, Aro E-M, Shikanai T (2016) NDH-1 and NDH-2 Plastoquinone Reductases in Oxygenic Photosynthesis Annu Rev Plant Biol. 67, 55-80, doi: 10.1146/annurev-arplant-043014-114752
2 Liua L-M, Bryana SJ, Huanga F, Yub J, Nixon PJ, Rich PR, Mullineaux CW (2012) Control of electron transport routes through redox-regulated redistribution of respiratory complexes
PNAS 109, 11431–11436, doi: 10.1073/pnas.1120960109
3 Roessler MM, King MS, Robinson AJ, Armstrong FA, Harmer J, Hirst J (2010) Direct assignment of EPR spectra to structurally defined iron-sulfur clusters in complex I by double electron–electron resonance PNAS 107, 1930-1935, doi: 10.1073/pnas.0908050107
4 Kimata Ariga Y, Matsmura T, Kada S, Fujimoto H, Fujita Y, Endo T, Mano J, Sat F, Hase T (2000) Differential electron flow around photosystem I by two C4-photosynthetic-cell-specific ferredoxins. EMBO J 19, 5041-50, doi: 10.1038/sj.emboj.7593319
5 Blanco NE, Ceccoli RD, Dalla Vía MV, Voss I, Segretin ME, Bravo-Almonacid FF, Melzer M, Hajirezaei M-R, Scheibe S, Hanke GT (2013) Expression of the Minor Isoform Pea Ferredoxin in Tobacco Alters Photosynthetic Electron Partitioning and Enhances Cyclic Electron Flow Plant Physiol 161, 866–879, doi: 10.1104/pp.112.211078

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