TRANSGENIC PERENNIAL RYEGRASS (LOLIUM-PERENNE) PLANTS FROM MICROPROJECTILE BOMBARDMENT OF EMBRYOGENIC SUSPENSION CELLS

Transgenic forage-type perennial ryegrass (Lolium perenne L.) plants h ave been obtained by microprojectile bombardment of embryogenic suspen sion cells using a chimeric hygromycin phosphotransferase (hph)gene co nstruct driven by rice Act1 5' regulatory sequences. Parameters for th e bombardment of embryogenic suspension cultures with the particle inf low gun were partially optimized using transient expression assays of a chimeric beta-glucuronidase (gusA) gene driven by the CaMV 35S promo ter. For the recovery of stably transformed clones, hygromycin selecti on using liquid and solidified media was tested. Initial selection in liquid culture medium allowed for a higher, compared with continuous p late selection using solid medium, recovery efficiency of transformed hygromycin resistant clones. Plants were regenerated from 23% of the h ygromycin resistant calli obtained. The transgenic nature of the regen erated plants was demonstrated by Southern hybridization analysis. Exp ression of the transgene in transformed adult perennial ryegrass plant s was confirmed by Northern analysis and a hygromycin phosphotransfera se enzyme assay.