Assessing the risk of herbicide resistance transfer via hybridisation between rye-grass species

Some cultivated rye-grass species, Lolium spp., such as perennial, L. perenne, and Italian, L. multiflorum, rye-grass, are economically important forage crops.

However, rye-grass species can become problematic weeds in arable rotations, especially with increasing cases of resistance to several important herbicides, including glyphosate.

Hybridisation between cultivated rye-grass forms and weed populations may spread resistance, although the risk of this occurring is not currently known.

This project will use a set of microsatellite markers to genotype cultivated rye-grass varieties on the AHDB Recommended Grass and Clover Lists and weed rye-grass samples from UK arable farms.

This molecular marker set is known to perform reliably across species and ploidy levels, diploid and tetraploid. This is despite the high heterozygosity typically seen in rye-grass populations, which requires pollen from other plants to set seeds, as it is an obligate outcrosser.

The molecular screening will be used to determine the genetic relationships.

The project will also conduct ploidy assessments of weedy types and observations of population ecology to determine species groupings, admixture and the occurrence of hybrids.

Collectively, the project results will generate a preliminary assessment of hybridisation, both in terms of current occurrence and continued hybridisation risk between commercial rye-grass varieties and weedy rye-grass populations in the UK.

This is a collaborative project between weed management experts, including the Weed Resistance Action Group (WRAG) and the BCPC Weeds Working Group, plant breeders and herbage seed growers.

BASE-UK is also providing access to its farmer-led knowledge exchange network dedicated to regenerative agriculture.

Ultimately, the project will develop guidance on practical management interventions to reduce the hybridisation risks identified, such as to achieve seed hygiene and purity.

The total project value includes in-kind contributions of £1,000 from each of the following companies: Germinal Horizon, Gowan Crop Protection Ltd, DLF, DSV, NFU Herbage Seed Levy Group and RAGT.

Stephen Moss Consulting is a sub-contractor in this project.

Providing answers to your questions

This research project was funded via a levy-payer-led commissioning process.