Expression of a sulphur-rich sunflower albumin gene in transgenic tall fescue (Festuca arundinacea Schreb.) plants

Transgenic tall fescue (Festuca arundinacea Schreb.) plants have been generated that express foreign genes encoding a rumen-stable protein rich in sulphur-containing amino acids. The aim was to improve the protein quality of a forage grass for ruminant nutrition. Chimeric sulphur-rich sunflower albumin (SFA8) genes, including an endoplasmic reticulum retention signal (KDEL), were constructed under the control of constitutive (CaMV 35S) and light-regulated (wheat Cab) promoters. These constructs were introduced into the tall fescue genome by microprojectile bombardment of embryogenic suspension cells. The sunflower albumin transgenes stably integrated into the plant genome as demonstrated by Southern hybridization analysis. The transgenic tall fescue plants produced the expected transcript, and the corresponding sulphur-rich SFA8 protein accumulated up to 0.2% of the total soluble protein in individual transgenic plants.