Applications of plant pathology: from field to clinic- preview

In conjunction with the British Society for Plant Pathology, this meeting will cover rapid responses to emerging pathogens, both plant and clinical.

It will also focus on the plant microbiome and its importance for plant and human health, detection of viral pathogens and the soil resistome. Here’s a peek of some of the speakers and their abstracts.

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Adrian_FoxAdrian Fox- Fera Science Ltd, York, UK

Adrian is the Senior Plant Virologist at Fera Science Ltd. As lead virologist, he delivers the virus diagnostic service in support of the UK plant health service as well as to a range of UK and overseas government and commercial customers.

The team utilises a range of both cutting edge and traditional techniques to provide diagnostics, supporting research, and advice on viruses, viroids, and phytoplasmas.

Adrian has authored or co-authored over 30 peer-reviewed papers, New Disease Reports and book chapters. He is a member of the International Committee on Plant Virus Epidemiology and is the chairperson of the European Association of Potato Research Virology Section.

Making the unknown known: The application of diagnostic technologies in plant health virology

Due to the obligate nature of viruses, plant virology has always been an early adopter of new diagnostic technologies. Until recently, the main diagnostic technologies applied in plant health laboratories were targeted and specific requiring a priori knowledge of the pathogens likely to be associated with a given host and symptom.

With the advent of Next-Generation Sequencing (NGS), the ability to detect the pathogens associated with plant diseases of unknown aetiology is becoming routine. The application of such approaches has resulted in an almost exponential increase in the number of previously uncharacterized viruses now being reported.

Whilst these discoveries have led to a deeper understanding of the diversity of the plant virome, the greatest challenge for plant health authorities in applying NGS now lies in differentiating between the pathogenic, commensal, or even mutualistic viruses. Pathogen characterisation in support of plant health risk assessment is a laborious process requiring demonstration of causation, host range studies, vector transmission studies and baseline surveillance. Some of these considerations can be addressed through experimental set up, or through follow-up volume testing, whilst others may take months or years of additional research.

An overview of the development of NGS for frontline plant virus diagnostics will be illustrated with case studies highlighting the opportunities and challenges of deploying NGS in a plant health/biosecurity setting.

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Carrie BradyCarrie Brady- University of the West of England, UK

I obtained my PhD in microbiology from the University of Pretoria, South Africa in 2008 working on a project to evaluate the taxonomy of the genus Pantoea using a multigene approach with specific focus on plant-pathogenic strains from Eucalyptus.

The results from this project prompted the restructuring of Pantoea with several novel species described and the reclassification of several more. I then completed a post doc at the Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria where I further expanded the multigene approach designed during my PhD to include more plant-pathogenic and -associated Enterobacteriaceae.

This project was continued at the BCCM/LMG Bacteria Collection, Gent University, Belgium in 2010 where I was a post doctoral research fellow. This project resulted in several taxonomic rearrangements and novel genus, species and subspecies descriptions in the genera Pantoea, Enterobacter, Brenneria and Dickeya.

In 2011 I joined the University of the West of England as a research fellow to work on taxonomy, pathogenicity and identification of the bacteria associated with Acute Oak Decline (AOD) in collaboration with Forest Research on a project funded by the charity Woodland Heritage.

 Impact of taxonomy on identification and detection of plant pathogens in the Enterobacteriaceae

The aim of taxonomy is to circumscribe taxa into monophyletic groups which are reflective of their genotypic, genomic and phenotypic characteristics. This can be difficult to put into practice especially for members of the family Enterobacteriaceae, where many species are phenotypically and phylogenetically closely-related despite representing genera from both clinical and plant hosts.

Over the years, numerous enterobacterial strains have been wrongly identified and species erroneously assigned at the genus level creating many taxonomic issues. There is also a blurred distinction between plant-pathogenic and clinical bacteria as several enterobacterial species are polypathogenic, meaning their taxonomy should not be studied separately. It is often necessary to clarify the taxonomy of causal agents of novel plant diseases before attempting to design a rapid identification or detection technique.

Multilocus sequence analysis (MLSA) scheme, based on short sequences of four protein-encoding genes, has provided a robust and reliable alternative to 16S rRNA gene sequencing for taxonomic and phylogenetic studies of plant-pathogenic and –associated enterobacteria. Concatenated analyses of gyrB, rpoB, infB and atpD gene sequences have resolved taxonomic issues within the genera Pantoea, Tatumella, Brenneria and Dickeya; supported the classification of many novel species and reassigned numerous strains to the correct species and genus.

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DR sandra denmanSandra Denman- Forest Research, UK

Sandra studied Plant Pathology at the University of Stellenbosch, South Africa. She has extensive experience in soil borne and stem canker diseases of native woody plants. Her main interests centre on tree disease aetiology, biology, epidemiology and management. Over the past decade her research has focused on diseases of oak, particularly oak declines.  She uses holistic, multidisciplinary research approaches to address tree health problems.

Proving pathogenicity in polymicrobial pathosystems

Causality of tree diseases attributed to primary pathogens is proven experimentally through successful completion of Koch’s Postulates. In complex disease syndromes, cause and effect is more difficult to prove experimentally because the 1 pathogen = I disease model is not suitable for multifaceted, polymicrobial diseases. Oak declines are well documented, complex disease syndromes.

Acute oak decline, which is characterised by weeping stem patches with underlying innerbark necrosis and the presence of larval galleries of the native buprestid Agrilus biguttatus, serves as a good model to develop an appropriate suite of tests that would provide compelling, empirical evidence of causal roles for key organisms consistently associated with the disease.

We propose a novel template for acquiring proof of a causal role where classical methods combined with molecular technologies are used to link microbes and gene function.

Applications of plant pathology: from field to clinic is on 18 April 2018 at Charles Darwin House, 12 Roger Street London WC1N 2JU.



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