Genomics Assisted Approaches for Improving Abiotic Stress Tolerance in Forage Grasses

Abstract

Ryegrasses, such as Perennial, ItalianRyegrassItalianand Hybrid ryegrassRyegrasshybridare globally important forage crops in cool season livestock agriculture, and make up most of the acreage used in grassland agriculture. These forages are grown chiefly in Northwest Europe, New Zealand and temperate regions of Japan, Australia, South Africa and South America. Regions dominated by permanent grassland tend to have reasonably high annual rainfall, while lower rainfall regions are dominated by arable crops. However, extreme and unpredictable weather events are likely to occur more often as a result of climate change. This may include dryer hotter summers, and wetter winters. Ryegrass forage crops would thus be exposed to a wide range of abiotic stresses, including drought, cold, flooding and even heat. Generating varieties which can perform well in response to all these diverse stresses is thus an important and difficult challenge for grass breeders. The advent of low cost, high throughput next generation sequencing and genotyping technologies provide new opportunities to increase the speed with which genetic improvement can happen. The availability of high density genotyping platforms makes genomic selection in forages a realistic prospect. They can also be used with great effect in marker-assisted backcrossing strategies to introgress desirable traits from ecotypes or other donor material. The ability of ryegrass and fescue to hybridize, opens up further opportunities for generating new genetic combinations with beneficial characteristics in terms of abiotic stress tolerance from fescue background with the traditional ryegrass properties in terms of forage quality and biomass yield.