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PhD Student Projects based at Wellesbourne

Student

Project Title

Funder

Project summary

  Lawrence
Bramham
Exploiting new sources of broad-spectrum resistance to Turnip mosaic virus in brassicas BBSRC
& Sakata
 

Turnip mosaic virus (TuMV) detrimentally affects a number of cultivated plant species of high socioeconomic importance. This is due to its broad host range, ability to be spread by over 89 aphid vector species in the non-persistent stylet-borne manner and the consequential inefficacy of pesticides and other, more conventional, disease management strategies.
It was ranked as the second most important virus infecting field vegetables worldwide and causes economic losses through diminished harvest yields and quality of produce.
TuMV is particularly damaging to members of the Brassica genus (cabbage, cauliflower, oilseed rape etc.), within which a large variety of morphotypes exist that provide the highest diversity of products derived from any single plant genus. A source of resistance to a range of TuMV strains has been identified within Brassica rapa (the most important brassica crop worldwide) however, due to the selection pressure that will result from deployment of this single resistance source, further sources of broad-spectrum resistance are required. This project aims to exploit previously found sources of broad-spectrum TuMV resistance by developing molecular markers for resistance-associated genes before, in collaboration with Sakata Seeds Ltd, assessing their use for the introgression of resistance into commercial varieties of TuMV-susceptible B. rapa.

  lawrence_bramham.jpg
               
  Scott Dwyer Biologically-based control of Varroa destructor

Elizabeth Creak Trust & University of Warwick

 

The ectoparasitic mite, Varroa destructor and the viral diseases that it transmits, are a key cause of European honeybee, Apis mellifera (EHB), overwintering colony losses. Varroa has developed resistance to many synthetic pesticides. Few remain that do not kill bees and current alternative measures are only partially effective. There is an urgent need for new control methods underpinned by fundamental knowledge to ensure their sustainable use.
Previous research shows Varroa are susceptible to lethal infections by entomopathogenic fungi (EPF), which have potential to be used as biocontrol agents. A number of EPF species are available commercially for arthropod pest control. EPF are considered to be low risk to people, and we have identified strains of fungi that infect varroa but do not kill EHB. However, there are knowledge gaps about how EPF interact with varroa and bees and this is an impediment to commercialisation and use.
This project focuses upon characterising virulence of strains and species of EPF against Varroa and bees through laboratory bioassays. As well as understanding the effects of temperature upon the activity of EPF as within the hive EHB maintain relatively warm temperatures which can inhibit fungal activity. And finally, investigating the effects of fungal treatment on transmission and activation of bee viruses through quantitative PCR and if fungal treatment has immune priming effects on immune pathways associated with antiviral responses.

   Scott Dwyer
               
  Andy Gladman Investigating the interactions between biopesticides and partial crop resistance for management of aphid pests of Brassica crops MIBTP  

Aphid infestations in Brassica crops bear a huge economic burden upon growers, leaving produce unmarketable due to distortion of foliage, contamination of the crop and potential transmission of damaging viruses. Current field control measures rely heavily upon conventional chemical products, however with the emergence and dissemination of insecticide resistance in aphid populations alongside neonicotinoid withdrawal, growers have access to ever fewer control options.
This research aims to explore a novel IPM strategy utilising partial varietal resistance to retard aphid development and fecundity, thus enhancing the performance of entomopathogenic fungi (EPF) biocontrol agents. Currently EPF are inviable for aphid control due to the multiple phases of cuticle shedding during aphid development allowing for EPF spores to be shed prior to germination - rendering the EPF ineffective.
Candidate Brassica accessions, identified through the scientific literature and RNASeq analysis of a brassica diversity set for accessions with upregulated JA signalling pathway genes, will be screened in an infestation study to determine aphid survival and rate of development between accessions. Bioassays will then be undertaken with numerous EPF strains to determine their virulence and speed of kill against aphids in identified partially resistant Brassica accessions relative to known susceptible plants to quantify the viability and efficacy of this IPM approach.

  Andy Gladman
             
  Shannon Greer

Broadening
and improving the Turnip yellows virus resistance base in oilseed rape (BITYR)

BBSRC
and Limagrain

 

Turnip yellows virus (TuYV) virus is transmitted by aphids and costs the UK oilseed rape (OSR) industry up to £180million p.a. in lost yield. The current method for controlling TuYV is by insecticide treatments that kill the aphid vectors. However strict regulations on insecticide application and growing insecticide resistances within the aphids have prevented the successful control of TuYV. Research has now been directed into introducing TuYV resistance into the OSR genome by utilising genetic diversity from its relatives. An example of this is Amalie an OSR variety with integrated TuYV resistance originating from B. rapa. The gene(s) responsible for TuYV resistance in Amalie have not been characterised and so it is hard to determine its effectiveness in controlling TuYV and its durability against resistance breaking. The project has three main objectives that will help broaden and improve the TuYV resistance base in OSR for the control of the virus. The first is to characterise the Amalie resistance gene(s), the second is to characterise novel sources of TuYV resistances from OSR relatives and the third is to integrate these novel sources of resistance into OSR.

  Shannon Easterlow
               
  Lisa King Understanding and Mitigating the Causes of
Yield Decline in Pea
MIBTP and PGRO  

The field pea (Pisum sativum) is an important legume grown for both human and animal consumption in over 110 countries worldwide. In the UK, growth is limited to areas within close proximity of processing facilities, which are situated across eastern England and Scotland. This has led to intensive production and yield declines of up to 40% in recent years, mostly attributed to a build-up of fungal and oomycete pathogens involved in the pea foot rot complex (PFRC). Important pathogens of the PFRC include Fusarium solani f. sp. pisi, Fusarium oxysporum, Aphanomyces euteiches and Didymella pinodella. Whilst initial research into the PFRC has consisted of field surveys, particularly in North America and Europe, to examine the prevalence, severity and identity of the pathogens involved, very little research has been conducted into the abundance, dynamics and interaction of these species within the complex, and crop rotation is currently the only disease management practice. Therefore, the aims of this project are to:

  1. Understand the components and dynamics of the PFRC as well as associated microbiota in the pea rhizosphere using both conventional and, in collaboration with the Processors and Growers Research Organisation (PGRO), amplicon sequencing approaches.
  2. Identify green manure and biofumigant crops that can suppress the PFRC.
  Lisa King
               
 

Nicholas Kuht

Enhancing salad onion quality and yield through understanding in-field variation

Waitrose CTP and G’s Growers

 

Salad onions are a high value UK vegetable crop consumed for their immature bulbs, green fleshy leaves and distinct flavour. Production is highly sensitive to a number of environmental, cultural and biotic factors that can affect the crop from seed germination to harvest maturity. Production of a uniform crop with little variation is key to attaining maximal marketable yields and economic returns for growers. In addition to the aforementioned factors, seemingly random patches of stunted salad onions have begun to be observed. The cause of this stunting though has yet to be identified and continues to be an issue for growers. This project aims to examine underlying variation in-field to elucidate different factors that influence salad onion variation and also to investigate the causative agents of stunting. The first year of this project was dedicated to mapping the variation that existed within commercial cropping, with the aim in the following three years being to investigate the causes of variation. The outcome from this research should be a greater understanding of the causes of variation, and it is hoped that recommendations can be provided to growers that will minimise their inputs and maximise returns.

  Nicholas Kuht
               
  Rosanne Maguire Phaseolus vulgaris:
adapting the missing link for sustainable production and consumption in the UK
MIBTP  

Dietary choices can reflect how the food system affects our health personally and as a society, our environment and ultimately contributes to climate change. Pulse crops can play an important role in sustainable food systems as they (1) are an excellent source of plant protein with numerous additional health benefits; (2) have the well-known environmental return of biological nitrogen fixation – reducing the need for synthetic fertilisers and as such indirectly reduce GHG emissions; and (3) are excellent crops to include in crop rotations to break cycles of pest and diseases.
This project will apply a transdisciplinary approach to the current common bean (Phaseolus vulgaris) molecular breeding programme at Warwick Crop Centre. The project aims to enhance understanding of users' and society's needs for delivering a full range of UK pulse breeding impacts. Specifically, impact is aimed at adapting common bean to the UK food system by providing UK consumers with a healthy source of home-grown plant protein and UK farmers with a profitable short-season legume break crop. In other words, home-grown haricot beans are a missing crop and ingredient that links sustainable food production and sustainable food consumption in the UK.

  Rosanne Maguire
               
  Tracey
Moreton
Integrated control of Sclerotinia disease in celery and lettuce G's and Waitrose CTP  

Sclerotinia sclerotiorum is a soilborne fungal pathogen that causes stem and crown rots in a wide range of crop plants resulting in extensive economic losses worldwide. The fungus can survive for several years in the soil as sclerotia which when close to the soil surface germinate carpogenically to produce mushroom-like apothecia. Subsequent release of air-borne ascospores then initiate the infection process. Control of S. sclerotiorum focuses on the prevention of ascospore infection with the use of fungicides, but generally there are no attempts to eradicate sclerotia. This project aims to explore practices that reduce sclerotial survival in order to improve Sclerotinia control in celery and lettuce in Spain. The main objectives are to:

1. Collect S. sclerotiorumisolates from UK and Spanish lettuce and celery crops and characterise using molecular genetics to identify any differences in population structure.

2. Determine the temperatures required to kill S. sclerotiorum sclerotia or prevent carpogenic germination for UK and Spanish isolates to evaluate the feasibility of solarisation.

3. Investigate other means of killing sclerotia such as bio-solarisation, bio-fumigation and anaerobic disinfestation.

  Tracey Moreton
               
  Daniel Wilson

Opportunities for IPM in annual crops grown outdoors.

Waitrose Agronomy Group and University of Warwick  

There is increasing pressure on farmers to reduce their reliance on synthetic chemical pesticides. This is for a range of reasons; including consumer concerns, environmental impact, decreasing availability of chemical pesticides and increasing incidences of pesticide resistance. Integrated Pest Management (IPM) is often promoted as a way forward. IPM in outdoor crops, however, presents many challenges. For example, in contrast to greenhouse crops, there is no environmental control and the retention of released biological control agents proves difficult. Annual crops such as field vegetables and salads are particularly challenging, as apart for field boundaries, there is little opportunity to establish stable ecosystems that support beneficial organisms.This project focuses on aphids, which are important pests of a range of crops and account for a large proportion of the insecticide applications made to vegetable and salad crops in the UK. It will consider generalist and specialist species and explore the effects of the injudicious use of insecticides on aphids and their natural enemies, methods of predicting periods of high aphid abundance and identify new approaches that can be incorporated into whole-crop IPM programmes.

  Daniel Wilson