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SoCoBio (Universities of Southampton, Kent, Sussex, Portsmouth and NIAB EMR)

Safeguarding UK hop production from Verticillium nonalfalfae: Using genomics to develop race-specific diagnostics and generate Verticillium resistant hop through Host Induced Gene Silencing (CASE project)

Supervisors

Dr Helen Cockerton (Project Leader) (NIAB EMR)  Expertise: Plant Pathology and Quantitative Genetics

Dr Alessia Busciano (School of Biosciences, University of Kent)

Dr Sue Crosthwaite (NIAB EMR)

 

Summary

Rational: Highly virulent races of the soil borne fungus Verticillium nonalfalfae has led to the decline of the UK hop industry. Once this lethal disease has established within a field it can only be combatted through this use of resistant varieties as there are no effective chemical means for control. Four V. nonalfalfae UK races have been characterised (mild, PV1, PV2, PV3), with two understood to have evolved exclusively in the UK. Published work has focused on identifying pathogenicity factors causing lethal wilt on the susceptible cultivar ‘Fuggle’ (PV1), a significant problem in continental Europe. By contrast, this PhD will investigate the resistance breaking UK races causing lethal wilt on the resistant cultivars ‘Wye Challenger’ (PV2) and ‘Wye Target’ (PV3).

Approaches: WP1 Confirming race types of the V. nonalfalfae culture collection through pathogenicity testing on standard cultivars. WP2 Genome sequencing of isolates taken from four UK race types. WP3 Identification of race specific pathogenicity factors through comparative genomics for use in the development of diagnostics. WP4 Validation of pathogenicity factors through knockouts of candidate genes in V. nonalfalfae and Host Induced Gene Silencing (HIGS)

Impact: Identifying regions of the genome unique to each V. nonalfalfae race structure will allow the generation of soil diagnostic tools to inform planting and management decisions in hop production. Whereas the use of HIGS will validate pathogenicity factors and potentially allow the generation of Verticillium resistant hop varieties. Existing funding has been secured to characterise novel sources of Verticillium resistance in hop through QTL mapping. However, understanding the race structure of UK V. nonalfalfae is an essential component of developing robust disease resistant hop varieties. This project will complement current work in the host and support hop breeders in the arms race against Verticillium.