Inhibition of Growth in Maize Embryos by Canavanine and Its Reversal

Abstract

Growth of maize embryos excised 15-40 days after fertilization and cultured in vitro is strongly inhibited by addition of canavanine to the culture medium at the rate of 20 mg./l. This inhibition is counteracted by addition of arginine; citrulline, ornithine, glutamic acid, and lysine also are partially effective in relieving the inhibition. It is suggested that canavanine acts as a metabolite antagonist of arginine, and that citrulline, ornithine, and glutamic acid are precursors in the biosynthesis of arginine in maize. The lysine effect is obscure. Different genetic strains of maize show variation in their sensitivity to canavanine and to reversal of this inhibition by other amino acids.