Lolium perenne L. (perennial ryegrass) is the most widely used turf and forage grass grown in temperate climates throughout the world, commonly found on sports grounds, and in cattle and sheep farming systems. The introduction of new cultivars of L. perenne with improved agricultural performance has relied on traditional breeding methods. Nuclear and plastid transformation provides an alternative approach to obtain plants with desired phenotypes, some of which would be difficult to achieve by classical breeding.