Improving sustainability of quantitative disease resistance against plant disease: a project to understand and counter host adaptation by downy mildew
Lead supervisor: Professor Jurriaan Ton, Animal and Plant Sciences
Co-supervisor(s): Professor Michael Brockhurst, Animal and Plant Sciences; Dr Joost Stassen, Animal and Plant Sciences
Deadline: Friday 24 February 2017
Please note: in the online application process please select ‘standard PhD’ not DTC option, and ‘Department of Animal and Plant Sciences’. Your application for this studentship should be accompanied by a CV and a 200-word supporting statement. Your statement should outline your aspirations and motivation for studying in the Grantham Centre, outlining any relevant experience.
About the Grantham Centre
Oomycete plant diseases, such as late blight and downy mildew, threaten food crops worldwide. At present, these diseases are controlled either by frequent fungicide applications, or single host resistance (R) genes. Alarmingly, both strategies are regularly failing, due to the ability of Oomycetes to develop fungicide resistance and break R genes. Therefore, crop breeders are increasingly focusing on ‘quantitative disease resistance’ (QDR), which is determined by multiple defence genes. It is generally assumed that QDR provides durable crop protection, even though empirical evidence for this assumption is lacking. Preliminary results from the Ton lab provided compelling evidence that downy mildew can adapt to QDR, suggesting that QDR is not as durable as is often assumed. This PhD project will study the (epi)genetic mechanisms by which downy mildew breaks QDR, design sustainable strategies to minimize this adaptation, and translate these strategies to protect lettuce against downy mildew disease.
Recent results from the Ton lab have shown that the downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa) can adapt to salicylic acid (SA)-controlled QDR in Arabidopsis. Three Hpa lineages from a common ancestor were propagated asexually on SA-treated wild-type plants (high QDR), untreated wild-type plants (medium QDR) and transgenic SA-deprived Arabidopsis plants (NahG; low QDR). After 15 generations, the Hpa strain from SA-treated plants had developed increased virulence via an improved ability to repress SA-inducible defence genes. By contrast, the strain from hyper-susceptible NahG plants showed reduced virulence with diminished ability to repress SA-inducible defence genes. Since the strains were propagated asexually, genetic recombination was excluded as a source of genetic variation. Although selection from genetic mutations cannot be excluded, the relatively fast adaptation to SA-dependent QDR suggests an epigenetic mechanism.
The successful applicant will:
- Employ next-gen DNA sequencing to assess global impacts of QDR selection on genetic and epi-genetic changes in Hpa.
- Determine the effectiveness of rotational immune priming treatments to counter QDR adaptation by Hpa.
- Test effectiveness of rotational immune priming treatments in lettuce to control downy mildew disease. This part of the project will be done in close collaboration with the industrial partner.
The student will benefit from expertise in plant pathology, epigenetics and bio-informatics (Prof. Ton & Dr. Stassen), expertise in microbial evolution (Prof. Brockhurst). The student will take part in an on-going BBSRC-funded collaboration between the P3 institute at Sheffield (p3.sheffield.ac.uk) and with a large international seed company. The collaboration will expose the student to a translational pipeline where results from basic research are translated into sustainable crop protection products, thereby providing the student with a valuable and diverse training experience.
Keywords: crop protection, phytopathology, evolution, adaptation, sustainable agriculture
Subject areas: Agricultural Sciences, Bioinformatics, Biotechnology, Plant Science, Genetics, Microbiology, Molecular Biology
This four-year studentship will be fully funded at Home/EU or international rates. Support for travel and consumables (RTSG) will also be made available at standard rate of £2,627 per annum, with an additional one-off allowance of £1,000 for a computer in the first year. Students will receive an annual stipend of £17,336.