© 2001 Heron Publishing—Victoria, Canada
Free amino acids in walnut kernels and young seedlings
S. Mapelli (1), I. Brambilla (1) and A. Bertani (1, 2)
1. Istituto Biosintesi Vegetali, CNR, Via Bassini 15, 20133 Milano, Italy / 2. Author to whom correspondence should be addressed (alcide@ibv.mi.cnr.it) / Received April 20, 2001
Summary
We investigated the composition of free amino acids in walnut (Juglans regia L.) seeds (embryo and cotyledons). We also examined xylem transport of free amino acids in young seedlings grown in the absence
of external nutrients. A relatively high concentration of free alanine was found in seed tissue, whereas a relatively high
concentration of citrulline was detected in young seedlings. Citrulline was the main free amino acid transported in the xylem
to stem and leaves. The negligible presence of citrulline, a non-protein amino acid, in the kernel and its presence in high
concentrations in all of the tissues of young seedlings, including cotyledons, embryonic axis, taproot and stem, suggest that
citrulline is synthesized during walnut germination. We conclude that citrulline plays an important role in nitrogen translocation
during walnut germination.
Keywords:
alanine, citrulline, Juglans regia, xylematic transport.
