Scientists have identified three regions of the wheat genome responsible for resistance to the grey field slug (Deroceras reticulatum).
The discovery, made by scientists at the John Innes Centre (JIC) as part of the SLIMERS project (Strategies Leading to Improved Management and Enhanced Resilience Against Slugs), a three-year Defra funded project which has brought together scientists, farmers and industry partners to tackle one of arable farming’s most persistent pest problems. Hopefully it paves the way for plant breeders to develop new slug resistant wheat varieties.
Work in this area started back in 2015, when scientists at the JIC screened wheat varieties from the historic Watkins Collection for natural slug resistance. One that stood out was Watkins 788, a landrace originally collected in Turkestan (part of modern-day Kazakhstan).
As part of SLIMERS, BOFIN’s (British On-Farm Innovation Network) ‘Slug Sleuth’ farmers trialled Recombinant Inbred Lines (RILs) developed from crossing Watkins 788 with commercial wheat variety Paragon. This allowed researchers to observe how the lines performed under varying soil types, weather conditions and slug pressure across the country. At the same time, laboratory and insectary experiments at the JIC provided controlled testing conditions to complement the field work.
Dr Victor Soria-Carrasco and his team carried out detailed slug feeding trials using grey field slugs supplied by farmers and citizen scientist ‘Slug Scouts’, who posted slugs collected from farms and gardens across the UK. Some of the slugs were also retained to establish breeding colonies for further research.
“Having slugs from different parts of the country was important,” explained Victor. “We know slug populations can vary, so using a wide range of grey field slugs helped us ensure the results represented real-world conditions.”
In total, researchers tested 77 Recombinant Inbred Lines alongside their parent lines. All the wheat lines had already been genetically sequenced, allowing scientists to identify the genomic regions linked to slug resistance more quickly than would previously have been possible.
The laboratory findings encouraged project partners to move on to on-farm trials in autumn 2025. However, very low slug numbers in the trials precluded clear conclusions on field performance explained Professor Keith Walters of Harper Adams University who analysed the trial results.
“Overall, however, the laboratory work demonstrates obvious potential which makes field trials under conditions with greater slug pressure an urgent requirement,” he said.
The discovery of the genomic regions linked to slug resistance gives plant breeders powerful new tools to develop commercial ‘slug resistant’ wheat varieties.
Dr Simon Griffiths of JIC said: “The thousands of data points collected in the feeding trials helped us identify the specific molecular markers or parts of the chromosome linked to slug resistance. With that understanding, and the screening protocol we have developed, plant breeders can now select for those markers to produce a slug resistant variety.”
