[Host-parasite metabolic relationship between puccinia graminis var. tritici and triticum vulgare (wheat) : I. Uptake of amino acids from the host].

Rust infected wheat plants were incubated with different (14C)-labelled amino acids. Uredospores that were formed during the incubation contained (14)C-activity. By analysis of these spores it was investigated whether the parasitic mycelium of Puccinia graminis takes amino acids from the host. It could be demonstrated that the applicated amino acids were taken up directly from the wheat leaf. The carbon sceletons of applicated lysine and arginine showed only little randomization of (14)C-activity. Glutamic acid, alanine and glycine isolated from uredospore protein showed a very strong alteration of the original label. The pools of free amino acids in the host and the parasite are in isotope equilibrium. This demonstrates, that synthesis of amino acids in the mycelium is quantitatively not important. By following the kinetics of incorporation of an amino acid it could be demonstrated that the amino acids enter the parasite as free amino acids and not in the form of proteins.