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Plant Health Fellowship (4) The taxonomy of phytoplasmas: a molecular approach - PH0403

Description
Phytoplasmas are bacteria-like pathogens that infect plants. Spread by insects, these pathogens have a number of biological properties that make them extremely hard to detect and identify; in particular they cannot be cultured in the laboratory (unlike bacteria) and they are found at very low concentrations in plants. As a result traditional diagnostic methods cannot be used, scientists are forced to turn towards molecular methods
i.e. ones based on the specific detection of phytoplasma DNA. At present the range of tests available is limited; often lacking sensitivity and/or the ability to distinguish between phytoplasmas and non-disease causing bacteria that can also be found on plants. Work is required to better understand the genetic make-up of phytoplasmas and to identify different genes within these pathogens which can be used as targets for accurately identifying different phytoplasma species. Once this has been acheived, better (i.e. more accurate and rapid) diagnostic tests can be developed.

Recently a number of non-indigenous EU-listed phytoplasmas have been identified in the UK, including European stone fruit yellows and most recently X-disease. In both these cases, improved diagnostics would have significantly aided the eradication process. Also while phytoplasmas represent a greater risk in tropical regions of the world, the increase in horticultural trade from such areas means that the risk of importing phytoplasma-infected material into the UK is now much greater than ever before. As a result improvements in the tools required to deal with phytoplasma diseases are urgently required.

With these facts in mind, this new project is being funded by Defra Plant Health Division (PHD) to develop a better understanding of phytoplasma taxonomy and biology. It is also important in providing an opportunity to train a new expert in this field. One of the recommendations made by the 2003 National Audit Office report (Protecting England and wales from Pests and Diseases), was that Defra Plant Health Division ensured a supply of young scientists in all the different plant health disciplines, in order to ensure expertise was available in future years and especially in areas where taxonomy which underpins diagnostic capabilities. This Fellowship achieves this; providing training in a field area where the UK currently lacks sufficient expertise.
Objective
To carry out R&D in the field of phytoplasma taxonomy and to supervise a suitable candidate with the aim of obtaining a PhD in this field to ensure continuation of taxonomic expertise underpinning UK Plant Health diagnostic capabilities.

Key aims:

1. To build a verified collection of type isolates.
2. To carry out in-depth molecular characterisation of the established collection.
3. Development of micro sequencing system for the accurate identification of phytoplasmas.
4. Development of accurate generic detection screen based on real-time PCR.
5. Using a model system, to carry out studies on host range and transmissibility
Project Documents
• Final Report : PLANT HEALTH FINAL REPORT: The taxonomy of phytoplasmas - a molecular approach   (200k)
Time-Scale and Cost
From: 2006

To: 2009

Cost: £74,025
Contractor / Funded Organisations
Central Science Laboratory
Keywords
Plant diseases              
Plant health              
Plants and Animals              
Fields of Study
Plant Health