Characterisation of a genetic region that conditions resistance to viral fungal and plasmodiophorid plant pathogens

Plant resistance (R) genes form an important component of integrated pest management strategies, decreasing reliance on fungicide and insecticide treatments. Recent work within our consortium has resulted in the identification of an R gene region that conditions resistance to viral, fungal and plasmodiophorid pathogens of sugar beet. This broad-spectrum resistance could be conferred by a number of tightly-linked R genes or by a single, novel gene. Subsequent scans of the genome revealed a number of loci that interacted with the broad-spectrum R gene locus to reduce disease levels. The aim of the project is to characterise the region of Beta vulgaris chromosome IV involved in resistance to diverse pathogens, in terms of its structure, its interaction with secondary genetic loci and its ability to control disease in the field. It is anticipated that the information and materials generated within the project will be used for marker assisted selection by sugar beet breeders and potentially for map-based cloning of the resistance gene(s) in subsequent work. A further aim of the project therefore is to facilitate further exploitation of this resistance locus. In year 1, large plant populations which segregate for resistance to diverse pathogens will be evaluated for disease resistance in controlled environment tests. Industry partners will conduct molecular marker analysis on these populations so that QTL maps can be generated. These maps will be used to identify secondary, interacting loci and to define a region of chromosome IV that contains the resistance alleles. Individual plants that show recombination in this region will be used to generate testcross families for fine mapping. In year 2, a set of polymorphic SNP markers will be generated and mapped within the region of interest. In year 3, the testcross families will be evaluated for disease resistance over a growing season in the field, allowing the efficacy of chromosome IV resistance through time to be determined. This phenotypic information will be combined with the SNP marker data to generate Mendelised, fine maps of the broad-spectrum resistance locus. The results and interpretation of this work will be submitted to peer review journals.

The identification of a broad-spectrum resistance locus represents an opportunity for the industry to develop resistance to multiple sugar beet pathogens based on a single genetic region. The project seeks to address this opportunity by defining the genetic region with markers and characterising its phenotypic effects, thus creating tools for commercial exploitation. Resistance loci to P. betae and BYV were reported for the first time recently by our group so the project addresses the opportunity to develop these novel forms of resistance. Resistance genes, particularly when they confer broad-spectrum resistance or occur as tandem arrays of homologues, are of interest to the wider scientific community. One of the aims of the project is to provide the opportunity for subsequent map-based cloning of the chromosome IV resistance gene(s).

The ability to introduce recently identified, novel forms of resistance into elite sugar beet lines is of benefit to the industry. To achieve this, molecular marker technology is required to screen for resistance alleles during crossing programmes. The project will develop a set of tightly linked, co-dominant SNP markers for novel chromosome IV resistance alleles which will be available for commercial use. The objective of the BBRO is to commission and implement research and technology transfer designed to promote a profitable, sustainable and environmentally sound beet sugar industry in which the competitiveness and profitability of UK growers and the processor may increase. Co-ordinated by British Sugar plc and Broom's Barn Research Centre, and guided by an industry survey of grower's technical needs, the BBRO technology transfer programme includes technical meetings alongside decision-maker training, field demonstration days, attendance at the Cereals and other major agricultural events, operator training courses, the British Sugar Beet Review, a weekly advisory bulletin, other technical bulletins in a variety of hard and electronic formats, telephone helplines and a plant clinic. Individual advice is given to growers by British Sugar's team of area managers. Some or all of these methods are selected according to the knowledge transfer needs of the topics to be communicated to decision makers. New knowledge will be actively transferred by platform presentations at scientific conferences and submission of papers to peer review journals. Likely journals are Theoretical and Applied Genetics, Plant Breeding and Plant Pathology