Allelopathic effects of exogenous phenylalanine: a comparison of four monocot species.

Exogenous phenylalanine stunted annual ryegrass but not switchgrass or winter grain rye, with deuterium incorporation up to 3% from phenyalanine-d . Toxicity to duckweed varied with illumination intensity and glucose uptake. Isotopic labeling of biomolecules through biosynthesis from deuterated precursors has successfully been employed for both structural studies and metabolic analysis.