Molecular improvement of perennial ryegrass by stable genetic transformation

Perennial ryegrass (Latium perenne 1.) is one of the most important turf- and forage grass in the temperate regions (Watschke and Schmidt, 1992). Genetic engineering of grasses will complement traditional breeding in the development of improved cultivars. The integration and expression of selectable marker genes in forage type perennial rye grass was demonstrated after microprojectile bombardment (Spangenberg et aI., 1995; Dalton et aI., 1999) or silicon carbide fibre-mediated gene transfer into suspension cells (Dalton et aI., 1998) and after direct gene transfer into cell suspension derived protoplast (Wang et aI., 1997). The time required from excision of the explants to transfer of the transgenic plants to soil in the earlier protocols was in excess of 10 months. This long tissue culture procedure increases the risk of generating undesirable somacIonal variation and consequently abnormal plants have been reported in perennial rye grass (CreemersMolenaar and Loeffen, 1991). We recently presented a more rapid biolistic transformation- and selection protocol for the production of large numbers of fertile transgenic perennial ryegrass plants and demonstrated its applicability to commercially interesting turf type cultivars (Altpeter et aI., 2000). Meanwhile an Agrabacterium-mediated perennial ryegrass transformation protocol has been developed in our laboratory and is compared with the biolistic gene transfer protocol. Transgenes were introduced into perennial ryegrass plants with the potential to improve rye grass mosaic virus resistance and to increase tolerance under iron deficiency conditions