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Feasibility of using diagnostic techniques for the evaluation of varietal resistance to stem canker in oilseed rape - VS0120

Stem canker (Leptosphaeria maculans) is the most damaging disease of oilseed rape in the major growing areas of the UK. Disease control through the exploitation of inherent resistance factors is now increasingly required in order to realise both the economic and environmental benefits desired by government, the industry and the public. Information on resistance is generated in Value for Cultivation and Use trials using an established technique in which stems are destructively sampled and the degree of symptom development assessed visually before harvest. The tests are labour intensive and thus costly. In addition, though operators are experienced and skilled in the technique, accuracy can be reduced by the presence of other diseaes, pest damage and other intrinsic technical limitations. Molecular diagnostic approaches for the detection of plant pathogens are well established in many cases. DNA primer sequences specific for the virulent and avirulent pathotypes of L maculans have been published and are available for use. The disease cycle of stem canker involves a long period of symptomless sytemic growth in the autumn and winter, and the rate of systemic growth is likely to be highly correlated with the final expression of symptom severity. A molecular diagnostic method of measuring systemic growth would thus provide a highly specific and sensitive means of measuring cultivar resistance. Since the labour intensive stem harvesting and assessement would be avoided, the costs of assessing resistance for VCU are likely to be significantly reduced, while accuracy would be improved. The objective of this proposal is to develop a method of detecting the systemic growth of L maculans in oilseed rape using DMA prin)ccs and the PCR, and to determine the feasibility of using the method to replace the current field procedures for resistance.
1. Confirmation of the specificity of primer sequences for UK group isolates - the primers will be tested against DNA extracted from a range of fungal isolates, differentiated on the basis of cultural characteristics, used in National List and plant breeders nurseries.

2. Optimisation of extraction procedures and the PCR reaction for pathogen detection in petioles. The extraction of fungal DNA from infected plant material using published procedures will be reviewed and modifications investigated. In particular, the use of more recent extraction procedures applied to extraction of fungal material from seed well be examined since these may offer an efficient means of removing substances inhibitory to the PCR reaction. PCR conditions for the primer sequences will be optimised for the LightCycler to allow detection of fungal material in small sections of leaf petiole.

3. Carry our field and laboratory studies to establish the relation between systemic infection of petioles and canker development, and obtain indication of whether glasshouse inoculated material could replace field grown plots in the future.
Project Documents
• Final Report : Feasibility of using diagnostic techniques for the evaluation of varietal resistance to stem canker in oilseed rape.   (2304k)
Time-Scale and Cost
From: 2000

To: 2003

Cost: £37,164
Contractor / Funded Organisations
National Institute of Agricultural Botany
Plant Varieties and Seeds              
Plants and Animals              
Variety Testing              
Fields of Study
Plant Varieties and Seeds