TRANSGENIC CANOLA AND SOYBEAN SEEDS WITH INCREASED LYSINE

We have increased the lysine content in the seeds of canola and soybea n plants by circumventing the normal feedback regulation of two enzyme s of the biosynthetic pathway, aspartokinase (AK) and dihydrodipicolin ic acid synthase (DHDPS). Lysine-feedback-insensitive bacterial DHDPS and AK enzymes encoded by the Corynebacterium dapA gene and a mutant E . coli lysC gene, respectively, were linked to a chloroplast transit p eptide and expressed from a seed-specific promoter in transgenic canol a and soybean seeds. Expression of Corynebacterium DHDPS resulted in m ore than a 100-fold increase in the accumulation of free lysine in the seeds of canola; total seed lysine content approximately doubled. Exp ression of Corynebacterium DHDPS plus lysine-insensitive E. coli AK in soybean transformants similarly caused several hundred-fold increases in free lysine and increased total seed lysine content by as much as 5-fold, Accumulation of alpha-amino adipic acid (AA) in canola and sac charopine in soybean, which are intermediates in lysine catabolism, wa s also observed.