Novel strategies for genetic improvement of disease resistance in perennial ryegrass

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Perennial ryegrass (PRG) provides the majority of forage for livestock in the UK, and delivers commercial returns to Germinal Holdings (GHL) through seed sales. Drechslera andersonii or net blotch is a serious fungal disease of PRG, and the UK is at high or medium risk. Biomass yield decreases can be more than 1t DM per hectare in the first cut. Few current varieties have good resistance, and the UK bred high sugar grass (HSG) varieties show poor resistance. Fungicide use is not a viable option. Reduction in the use of HSG varieties will lead to decreasing sales and increased imported varieties with higher resistance, but without the high sugar content, which improves ruminant nutrition efficiency and reduce GHG emissions from them. A 20% reduction in HSG seed sales for example would have serious commercial implications for GHL. IBERS, Aberystwyth University will collaborate with GHL to breed net blotch resistant HSG varieties using a novel backcross strategy aided by genomic selection. This will increase the speed and reliability with which disease resistant hybrids recover previous values of agronomic and HSG traits, and thus help GHL maintain or increase market share.