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Reference CTP-SAI-067

‘Living with the Enemy’; The crucial role of varietal tolerance in potato cyst nematode management

Reference CTP-SAI-067

‘Living with the Enemy’; The crucial role of varietal tolerance in potato cyst nematode management

Dr Matthew Back (Harper Adams University),
Dr Katarzyna Dybal (Harper Adams University),
Dr James Price (James Hutton Institute),
Dr Misghina Teklu (Wageningen University)


Potatoes are globally important food crops (ranked 4th in the world), providing an important source of carbohydrate, dietary fiber and vitamin C. In 2022, 126,584 ha of potatoes was grown in the UK (Defra, 2022), fulfilling 73% of the country’s requirement. Crop yields are threatened, however, by a prevalent and highly persistent pest; the potato cyst nematode (PCN) (Globodera pallida and G. rostochiensis). Nematicides have provided growers with an important tool for protecting yields where modest populations of PCN are found (2-15 eggs g-1 soil), but only one ‘robust’ nematicide remains in the armoury, fosthiazate, and this could be revoked under current legislation. Varieties with resistance to G. pallida (the dominant species – found in 89% of potato growing land in England and Wales) are becoming more widely available in some potato markets e.g. processing. While varietal resistance reduces nematode population growth, under heavy infections, it does not protect the yield of the plants. Tolerance, on the other hand, is the ability of the potato to tolerate parasitism by PCN and continue to produce an acceptable yield. Used without resistance, there is a risk that a tolerant variety would lead to further multiplication of PCN, causing problems in future potato crops. However, there are varieties, such as Camel, that possess both resistance and tolerance to PCN. Such varieties, could provide a sustainable (pesticide free) and a long-term solution to controlling PCN population growth while also providing yields to match increased demands.

There is currently no simple way of measuring whether a variety is PCN-tolerant or not which significantly impacts our ability to develop and deploy varieties with increased tolerance. Tolerance is a complex trait that has been attributed to a combination of root responses, root growth characteristics and general plant stress response (Blok et al., 2018). Moreover, it can be challenging to assess under field conditions due to variations in environmental conditions (Gartner et al., 2021). On the other hand, glasshouse studies with pre-determined population ranges enable tolerance to be assessed using the Seinhorst Yield Loss Model (Seinhorst, 1965 and 1998). This approach is used in work on other nematode genera such as root knot nematodes (Meloidogyne spp.) (Teklu et al., 2022) but less commonly for PCN. However, the above method is tedious, time consuming and requires large quantities of inoculum. Potato breeders need, a rapid, simple and robust method of measuring tolerance. This could be achieved through measuring biochemical factors that might be associated with tolerance, such as variations in phytohormones, e.g. abscisic acid, which accumulates in response to plant stress. Cytokinin concentration may also vary between tolerant and intolerant plants due to production in meristematic tissue, coinciding with the invasion points of PCN (Grove, 1999). Evans and Haydock (1990) indicate that tolerance may partly be influenced by differences in the hatching factors produced by different varieties, but this has not received a great deal of attention. Finally, with changes in global climate, it is important to understand how varietal tolerance is impacted by external abiotic factors such as water stress and different soil types and whether the stability of tolerance is altered by different conditions. In 2022, extreme weather conditions affected potato yields in European countries such as Belgium, Holland, France, Germany; The North-Western European Potato Group indicated a yield decline of 6% as compared to the previous year (NEPG, 2022).


1. Evaluate and compare the performance of varieties with resistance and tolerance under glasshouse and validate the results in field conditions, using ranges of densities to estimate damage threshold parameters using the Seinhorst model. Following this we will down scale in terms of nematode densities and pot size towards developing a simple method of tolerance testing. We will also assess correlation between plant growth i.e. canopy development, foliar abscisic acid accumulation, PCN root invasion and tolerance.

2. Explore differences between nematode hatching, attraction and root invasion in response to tolerant and intolerant potato plants. Studies may investigate qualitative difference between root leachates in relation to hatching and trackable, physical, changes near the feeding site (syncytia) using confocal microscopy and plant responses to the pest

3. Investigate the stability of varietal tolerance under varying water stress regimes and in contrasting soil types. Glasshouse and controlled environment studies will be used to determine PCN damage thresholds under contrasting conditions. Studies will consider differences between species and pathotypes of G. pallida


The student will be registered with Harper Adams University.


The student undertaking the project will benefit from complimentary training and guidance provided by Harper Adams University, James Hutton Institute, The Morley Agricultural Foundation and Wageningen University. The project will include a mixture of field, glasshouse and laboratory-based work, providing practical skills in agronomy, nematology, molecular biology, microscopy and data analysis

Students will have access to training in key bioscience areas (bioinformatics, statistics and mathematics) to enhance employability and research capability.

The CTP – SAI ( is a groundbreaking partnership between leading businesses, charities and research providers offering outstanding training for the agri-food sector

All CTP-SAI students will receive the Leadership and Management training provided by MDS ( and will create their Personal Development Plan (PDP) to identify their development needs and areas of strength. Each student will receive individual coaching and mentoring with regards to their career plans and skills development (in addition to the scientific project supervision).


Placements are a key feature of CTP and UKRI-BBSRC expects all doctoral candidates on a CTP programme to undertake a placement. Placements can be in the form of research placements (3-18 months duration) or used more flexibly for experiential learning of professional skills for business and/or entrepreneurship. All placements are developed in collaboration between the partners with input from the doctoral candidate.


Contact Dr Matthew Back ( for an informal discussion on the research content of this PhD.

This studentship will begin in October 2024. The successful candidate should have (or expect to have) an Honours Degree (or equivalent) with a minimum of 2.1 in Plant Science, Applied Statistics, or other related science subjects. Students with an appropriate Masters degree are particularly encouraged to apply.

We welcome UK, EU, and international applicants. Candidates whose first language is not English must provide evidence that their English language is sufficient to meet the specific demands of their study. Candidates should check the requirements for each host organization they are applying to, but IELTS 6.5 (with no component below 6.0) or equivalent is usually the minimum standard.

This studentship is for four years and is fully funded in line with UKRI-BBSRC standard rates. These were for 2023/24, an annual maintenance stipend of £18,622, fee support of £4,596, a research training support grant of £5,000 and conference and UK fieldwork expenses of £300.

To be classed as a home student, candidates must meet the following criteria:

  • Be a UK National (meeting residency requirements), or

  • Have settled status, or

  • Have pre-settled status (meeting residency requirements), or

  • Have indefinite leave to remain or enter

If a candidate does not meet the criteria above, they would be classed as an international student and must demonstrate the ability to meet the supplement in fees required for an international student.

Anyone interested should complete the online application form before the deadline of 7th January 2024. interviews will be held during January 2024.

Please contact for further application details.

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