Award details

Molecular genetic tools for manipulating pathogenicity/avirulence genes in cereal fungal pathogens: Stagonospora nodorum & Mycosphaerella graminicola

Reference	BBS/E/C/00823335
Principal Investigator / Supervisor	Dr John Hargreaves
Co-Investigators / Co-Supervisors
Institution	Rothamsted Research
Department	Rothamsted Research Department
Funding type	Research
Value (£)	327,031
Status	Completed
Type	Institute Project
Start date	01/04/1997
End date	31/03/1999
Duration	24 months

Abstract

The aim is to develop molecular genetic technology for isolating and manipulating pathogenicity and avirulence genes from the economically important Septoria diseases of cereals; Septoria tritici (Mycosphaerella graminicola) and Stagonospora (Septoria) nodorum (Phaeosphaeria (Leptosphaeria) nodorum). Efficient gene transformation procedures will be developed for both these fungi employing plasmids containing dominant drug (hygromycin B and phleomycin) or fungicide (carboxin) resistance genes as selectable markers. The use of autonomously replicating sequence to enhance transformation frequencies will also be investigated. Methods for screening large numbers of non- pathogenic Septoria mutants will be developed. Mutants will be generated using either conventional mutagenesis techniques (UV light or chemical mutagens) or by transformation-mediated gene disruption, in conjunction with restriction enzyme- mediated integration (REMI). Genes necessary for pathogenicity will be recovered by gene complementation of the non-pathogenic mutants. The relevance of identified genes to pathogenicity and virulence will be confirmed using gene disruption by transformation with defined DNA sequences in order to construct null mutations within the cloned gene. In this way, it should be possible to identify key fungal products required for pathogenicity and to study their interaction with host cells. Furthermore, identified key processes that determine pathogenicity in the Septoria complex may be targeted in the search for effective, long- lasting and environmentally-friendly crop protection agents. Objectives 1996 In the coming year we intend to concentrate our efforts on developing molecular genetic tools necessary for manipulating Septoria tritici genes. Attempts to improve transformation frequencies will be made through vector improvement and by identifying fungicide resistance genes that can be used as selectable markers for gene transfer. The use of restriction enzyme mediated integration to generate mutants carrying tagged mutations will be investigated and pathogenicity screens for identifying non- pathogenic mutants will be developed. 1997 In the comming year we intend to focus our effort on S. tritici. Two lines of research will be persued. First, we will continue to apply and develop molecular genetics for this disease with the view to applying these techniques to validate potential fungicide targets and to identify new modes of action. Work on validating HPPD as a fungicide target and on developing carboxin-resistance as a selection marker for transformation will continue. Second, we will concentrate on defining the factors that determine the pathogenic habit of S. tritici so that key events in the disease cycle can be used to develop rapid high through- put methods for screening for non- pathogenic mutants. This approach is necessary because of the relatively long latent period before symptoms appear with this disease. Emphasis will initially be placed on events that occur on the leaf surface prior to invasion of the leaf tissue. During the next year we also expect to initiate work the molecular genetics of cell wall biogenesis in S. tritici in order to help understand mechanisms underlying interactions with the host plant. Understanding cell wall biosynthesis in this pathogen could also identify new modes of action for chemical or genetic intervention.

Summary

unavailable

Committee	Closed Committee - Agri-food (AF)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
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