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 gener ated that express foreign genes encoding a rumen-stable protein rich in sul phur-containing amino acids. The aim was to improve the protein quality of a forage grass for ruminant nutrition. Chimeric sulphur-rich sunflower albu min (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 g enome as demonstrated by Southern hybridization analysis. The transgenic ta ll fescue plants produced the expected transcript, and the corresponding su lphur-rich SFA8 protein accumulated up to 0.2% of the total soluble protein in individual transgenic plants.