Genetic improvement of fibre traits in perennial ryegrass

Genetic changes in fibre characteristics of perennial ryegrass (Lolium perenne) may enhance degradability and thereby improve voluntary feed intake and energy availability from ingested grass. Plant breeding and genetic modification (GM) approaches to altering fibre composition have been initiated, with the ultimate objective of developing cultivars with improved fibre degradability. Ryegrass was modified with gene constructs designed to reduce the activity of key genes in lignin biosynthesis, a major component of fibre that impedes digestion. Concurrently, a grass fungal endophyte was manipulated to express enzymes that digest the structural components of grass fibre. Development of new analytical tools have enabled mining of a diverse collection of ryegrass germplasm, and natural variants were identified for both lignin concentration and levels of specific cell wall compounds that were shown to correlate with forage digestion rate. Both conventional breeding and GM strategies may be exploited to improve degradability traits in perennial ryegrass but further development will be required.