The potato cyst nematodes (PCN) – Globodera pallida and G. rostochiensis cause damage valued at over £50 million in the UK each year. They are present in two thirds of potato growing fields in the UK and the withdrawal of effective nematicides used by farmers to control PCN means that the future of the crop is threatened for many growers. On a worldwide basis plant parasitic nematodes are thought to cause damage valued at over 100 billion US Dollars each year.
Many plant parasitic nematodes, including PCN, are biotrophic and induce complex feeding structures (syncytia – see picture) in their hosts. The syncytium is a large, multinucleate metabolically active structure and its formation requires massive reprogramming of plant gene expression. Understanding how nematodes induce these structures in plants is an important goal of our work.
Effector biology
Like other biotrophic pathogens, PCN secretes effectors into its host in order to establish infection and to suppress host immunity. We work with other groups in the Dundee Effector Consortium to understand how nematode effectors function in plants.We have used genomics to identify the full effector complement of PCN and undertake a range of functional studies on these proteins. Cell biology tools are also increasingly important for our work.
Genomics
Much of our work uses genomics tools. We have been partners is a wide range of sequencing projects including those for Globodera pallida and G. rostochiensis as well as the root-knot nematode Meloidogyne incognita and the pine wilt nematode Bursaphelenchus xylophilus. We have also undertaken transcriptome analysis for other nematodes.
Nematode diversity and avirulence
Resistance genes against biotrophic pathogens operate by detecting pathogen effectors or their activity. Effectors that are recognised in this way are termed Avirulence (Avr) genes. A virulent pathogen does not contain the recognised avirulence gene and is therefore able to overcome a particular resistance source.
Nematode populations display a wide range of virulence against resistance sources. We have a long track record of investigating variation in PCN for diagnostic purposes and in relation to virulence. We have undertaken work that has identiied regions of the G. pallida genome that are under selection when the nematodes are selected for virulence against two commonly used resistance genes Gpa5 and H3. A better understanding of nematode avirulence genes offers the prospect of improved resistance breeding tools.
Scottish Governement PCN project
The threat posed by PCN to the future of the Scottish seed potato industry led to a large working group with a range of potato industry, government and academic backgrounds being set up to identify a strategy and key recommendations for dealing with PCN. As a result of the work done by this group, the Scottish Government awarded funding for a fully integrated 5-year project of scientific research and knowledge exchange with an aim to deliver a sustainable potato and bulb industry for Scotland through the management of Potato Cyst Nematode (PCN). The project is led by the Plant Health Centre. Our scientists play a key role in many areas of this project. Details of this project and project outcomes can be found on the PCN Action Scotland website.
