Award details

Genetic modulation of surface coat variation in Caenorhabditis elegans and its applicability to bacterial pathogenesis of plant parasitic nematodes

Reference	BB/F02388X/1
Principal Investigator / Supervisor	Dr Keith Davies
Co-Investigators / Co-Supervisors
Institution	Rothamsted Research
Department	Plant Pathology and Microbiology
Funding type	Research
Value (£)	85,183
Status	Completed
Type	Fellowships
Start date	01/01/2009
End date	31/12/2009
Duration	12 months

Abstract

The surface coat of the cuticle of animal parasitic nematodes can change significantly within hours in response to changes in the environment such as entering a host and this includes the migration of plant parasitic nematodes from soil to within plant roots. The ability to modulate the nematode surface coat affects the attachment of Pasteuria endospores. The proposed fellowship will initially investigate the genetic basis for changes to the surface coat that putatively provides resistance to bacterial pathogens in C. elegans. Mutagenesis experiments have identified genes that alter the surface coat of C. elegans and are responsible for the adhesion of the bacterium Microbacterium nematophilum. Screening for such genes has not reached saturation and further mutagenesis experiments will be undertaken and the nematodes assayed for alterations in susceptibility to bacterial adhesion by growing mutant nematodes in the presence of bacterial pathogens and selecting individuals with altered susceptibility. Selected lines will be assigned to one of six linkage groups (autosomes 1-V and X chromosome) by outcrossing experiments and the mutations mapped and then cloned and sequenced. The surface coat of the nematodes showing altered susceptability to bacterial attachment will be characterised by lectin staining and cuticle fragility tests. Genes associated with the ability to alter surface coat properties of the cuticle which are completely correlated with bacterial adhesion will be used to identify homologous genes in plant parasitic nematodes (Meloidogyne spp.) by BLAST searches of the plant parasitic nematode non-redundant databases. These genes with then be cloned and used in complementation experiments to establish whether or not the surface coat genes from Meloidogyne spp can be used to re-establish changed surface coat phenotypes in C. elegans.

Summary

Food security is already a serious problem in many parts of the world. This problem is likely to increase over the next several decades due to anticipated increases to human population , competition for land to grow bioenergy crops together with climate change brought about by global warming. Therefore, large increases in crop production are essential. Water availability is a huge constraint on crop production and plant parasitic nematodes are major pests that detrimentally affect plant roots and compromise their ability to take up water and minerals. It is estimated that crop losses due to nematodes are in the region of $100 billion annually. Since the mid-20th Century plant parasitic nematodes have been controlled by the application of nematicides but these chemicals are some of the most toxic agents used in agriculture. Therefore, over the last 20 years, due to environmental and human safety concerns several products have been removed from the market and alternative control methods sought. The Pasteuria group of bacteria are parasites of water fleas (Cladocerans) and plant parasitic nematodes (Nematoda). Pasteuria spp. have been associated with plant parasitic nematode suppressive soils and been shown to have potential to be developed into a biological control agent. One of the major constraints to their development as a biological control agent is their host specificity, which limits their utility; spores of the bacterium can adhere to, infect and prevent egg production by females from one population of plant parasitic nematode but not necessarily another. The attachment of the infective spore appears to be the key stage in determining parasitism by the bacterium. My research has been focused on understanding the pathology of this nematode parasite and recently, in collaboration with Prof. Valerie Williamson at University of California, I have developed several inbred lines of plant parasitic nematode that exhibit differential susceptibilities to this bacterium, the parental strain of which is currently being sequenced by Prof. Charles Opperman at University of North Carolina.. Recent research by Prof. Jonathan Hodgkin in Oxford has shown that multiple genes affect the ability of bacterial pathogens such as Microbacterium nematophilum to cause disease and some of these genes are associated with changes to the surface properties of the nematode cuticle. During this project I aim to learn how to identify and positionally clone selected genes that lead to changes in the cuticle of Caenorhabditis elegans that affect the ability of the bacteria to cause disease and see if similar genes are present in plant parasitic nematodes that relate to the sensitivity of plant parasitic nematodes to Pasteuria penetrans. In the short term this research will establish whether or not the genes responsible for the modulation of the surface coat in the model nematode in C. elegans is applicable to plant parasitic nematodes. In the longer term, understanding the genetics of cuticle variation in relationship to Pasteuria pathogenesis will help in the deployment of strains of Pasteuria that can suppress a range of nematode pests and act as a biological control agent, as an alternative to using chemical pesticides.

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	Crop Science, Microbiology, Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	Fellowship - Institute Development Fellowship (IDF) [2006-2010]
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search