Knowledge for a sustainable world

BSc, PhD
Professor Susan E Seal
Principal Scientist; Professor of Molecular Biology; Molecular Plant Pathologist

Agriculture, Health and Environment Department

Natural Resources Institute, Faculty of Engineering & Science

+44 (0)1634 88 3602

After obtaining a BSc Honours Microbiology degree in 1984 from Imperial College (London, UK), Professor Susan Seal gained a preliminary training in molecular biology at Genentech Inc. (San Francisco, USA) carrying out research on an auto-immune disease. Further research experience in molecular biology was acquired through PhD studies at the University of Bath on identifying pathogenicity genes in the plant pathogen Xanthomonas campestris pv. vesicatoria. During this time she decided on a career in research to benefit agriculture in developing countries and obtained scholarship funding to do fieldwork in Indonesia.  Thereafter she worked as a postdoctoral scientist at The Sainsbury Laboratory, John Innes Centre developing DNA-based diagnostic tests for Ralstonia solanacearum, one of the most important tropical plant pathogens. Several tests were developed and Sue was employed by NRI in 1992 to transfer these tests to a range of overseas countries and develop new molecular diagnostic projects.

Since joining NRI, Sue has overseen the molecular diagnostic laboratories at NRI, as well as establishing molecular-diagnostics laboratories in developing countries, and teaching MSc courses ('Molecular diagnostics', 'Plant pathology', 'Organisms and Systematics' and 'GM Crops'). In 2009, she became Leader of the Molecular Virology and Entomology Research Group at NRI, which focuses on applied as well as strategic research for controlling pests and diseases of tropical food crops especially those caused by viruses and insect vectors on cassava, sweet potato, yams and vegetables. These root and tuber crops play key roles in food security, poverty reduction, and income generation in Sub-Saharan Africa.

Sue has led ~60 research projects at NRI, the larger of which are outlined below in chronological order with their funding source given in brackets.

  • Set up of molecular diagnostic laboratories in Asia and Africa (ODA)
  • Cyprus national quarantine diagnostic services consultancy (EC, Govt. Cyprus)
  • Yam potyvirus research (Worldbank, Gatsby Charitable Foundation, ODA)
  • Identification of a banana bacterial wilt pathogenicity locus (ODA)
  • Development of diagnostics for bacterial pathogens of vegetables (ODA)
  • Molecular characterisation of aflatoxin producing fungi (ODA)
  • Diagnostic tools for corn stunt complex (funding ODA)
  • Diagnostics for a fungal pathogen (Mycospharella fijiensis) of banana (ODA)
  • Diagnostics for Cassava brown streak virus, and sweet potato virus disease (DFID)
  • Detection and characterisation of yam viruses (EC, CIRAD, Kebbi State, Nigeria)
  • Genetic linkage map and molecular markers in groundnut (DFID)
  • Review of suitability of transgenic crops for developing countries (DFID)
  • Development of diagnostic tools for fish trematodes (INCO-DEV, EC)
  • Identification of existing biosafety capacities and initiatives available in the CORAF sub-region and needs for research and training (FARA)
  • 'Green, white, blue and red' biotechnologies in developing countries (EC)
  • Molecular typing of begomoviruses (DFID)
  • Transcriptomics/genomics of whiteflies (UoG and BMGF)
  • Development of On-Farm Robust Diagnostic Toolkits for Yam Viruses (BMGF)
  • Enabling research tools for cassava virologists and breeders (BMGF)

Research on the above projects has led to the publication of >100 refereed journal papers, reviews and book chapters, as well as several 'Briefing Papers'. The projects above have also incorporated supervising the research of a range of MSc and PhD (>25) students.

Current research interests focus on using molecular biology tools to generate an improved understanding of the factors contributing to the spread of cassava and yam disease epidemics in Africa and developing novel technologies for their control. The research ranges from using the latest next generation sequencing technologies to determine genome and transcriptome data for the vectors (members of the Bemisia tabaci species complex) of the cassava viruses, to developing robust, low-cost diagnostic technologies for such plant viruses and specific populations of their vectors which appear to be driving the spread of epidemics.  The aim is to deliver research outputs that reduce the impact of root and tuber crop virus diseases in sub-Saharan Africa, and hence improve food security for smallholder farmers for whom cassava and yam are their major staple crop.

Project Leader for project entitled 'Enabling research tools for cassava virologists and breeders' (2013-2017, £0.5 million funded by The Bill and Melinda Gates Foundation )

Cassava is an essential food security crop, but its production is greatly limited by cassava virus diseases driven by super-abundant populations of the whitefly vector, B. tabaci, which appear to be an invasive form. In order to develop novel whitefly-management technologies and to ensure their successful adoption by resource-poor farmers, an improved understanding of the mechanisms generating the super-abundance cassava whitefly populations is required. A key step in this process is the development of accurate, robust and easy-to-use diagnostic tools that differentiate the different African cassava whitefly species. At present, population identification is based on the partial sequence of the mitochondrial cytochrome-oxidase 1 gene (mtCO1). This diagnostic has several drawbacks, the most serious being that it is a mitochondrial marker and hence is inherited maternally. The proposed project will address the need for improved whitefly diagnostics by studying biological properties and nuclear gene sequences for the different cassava 'mt-CO1' populations, focusing on identifying diagnostic targets (i.e. gene sequence differences) present in the super-abundant whitefly populations infesting cassava in sub-Saharan Africa. The knowledge and new diagnostic tools will improve our understanding of the mechanisms driving plant-virus epidemics and for identifying key intervention points. As such they have the potential to create significant impact both in the scientific community and through improved African cassava whitefly, and hence virus disease control.

This project will also assess the suitability of a novel method to develop infectious clones (ICs) of cassava brown streak viruses (CBSV, UCBSV) and NRI is coordinating an international team to share resources and draw up standard operating procedures (SOPs) for the use of ICs in SSA. This will link directly with the 'Disease diagnostics for sustainable cassava productivity in Africa' proposal at the Mikocheni Agricultural Research Institute (MARI) Tanzania, which aims to minimize both the occurrence as well as impact of cassava virus diseases and their associated insect (whitefly) vectors.

Project Leader for project entitled 'Development of On-farm Robust Diagnostic Toolkits for Yam Virus Diseases' (2012-2016, ~US$1.5 million funded by The Bill and Melinda Gates Foundation)

Yams are propagated vegetatively through their tubers, which leads to an accumulation of tuber-borne diseases in farmers' planting material and subsequent serious crop yield losses. The economically-important tuber-borne diseases are caused by viruses, and the only effective method of controlling these virus diseases is to use virus-free planting material. The scarcity and associated high expense of such material has been identified as one of the most important critical constraints to increasing yam production and productivity in W.Africa. A separate Bill and Melinda Gates Foundation funded project 'Yam Improvement for Incomes and Food Security in W.Africa (YIIFSWA)' (of which NRI/Professor Seal is also a partner) will address this by supporting the supply of high quality breeder and foundation seeds, and promoting a seed yam certification system to support the production and sustainable supply of high quality seed yams through farmer seed growers and commercial seed entrepreneurs. There is a resulting urgent need to develop on-farm diagnostic kits for yam viral diseases to enable this certification in the field.

The 26 virus species that have been reported to infect yams worldwide fall into nine taxonomic genera, but only three of these genera (badnaviruses, potyviruses and cucumoviruses) have been shown to cause important diseases and be widespread in recent surveys (2004-2009) across 100 yam growing locations in W.Africa. In addition to the normal virus infection process, some of the 12 yam badnavirus species appear to be integrated into the host genome of some of the widely cultivated Dioscorea species. Integrated badnavirus sequences are termed 'endogenous pararetroviruses' (EPRVs). Of particular concern is that EPRVs can be 'activatable', i.e. able to replicate and initiate virus infections de novo from their sequences integrated in the host genome. This poses serious problems for virus-indexing facilities as material free from virus particles and symptoms can, when stressed, become infected. Therefore it is essential to improve existing diagnostic tools for broad-specific detection of viruses and EPRVs, particularly in germplasm selected for wide dissemination in YIIFSWA. The yam lines containing 'activatable' EPRVs will need to be removed from the multiplication process as they cannot be 'cleaned' of badnaviruses and will pose a serious long term threat to the genuinely virus-free yam lines.

Leader of the Molecular Virology and Entomology Research Group (NRI) Vice Chair Faculty of Engineering and Science Research Degrees Committee Representative on Faculty Research and Enterprise Committee ‘Impact Director’ and Board Member for CONNECTED (GCRF-network for African Vector-Borne Plant Viruses, led by University of Bristol)
  • Developing Country and Societal Impact Award, received from Lord David Sainsbury at the 25 year anniversary of The Sainsbury Laboratory (2013),
  • Invited to award ceremony for major contribution to the winning of the Queen's Anniversary Prize for ground-breaking work on cassava (2016).
  • Editorial Board Member of Frontiers in Phylogenetics, Phylogenomics, and Systematics, and Pathogens (Plant Pathogens subsection, MDPI)
  • Membership of the Royal College of Science, Imperial College, London UK; CONNECTED (GCRF-network for African Vector-Borne Plant Viruses), Biochemical Society, International Society for Tropical Root Crops
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