Seasonal Dynamics of Nitrogenous Compounds in a Nitrophilic Weed II. The Role of Free Amino Acids and Proteins as Nitrogen Store inUrtica dioica

摘要

The free amino acid fraction, representing the most important nitrogen store in the overwintering below ground plant parts ofUrtica dioica, consisted mainly (up to 80) of asparagine and arginine. While asparagine was dominant in rhizomes, up to one year old, argrnine was specifically accumulated in the older rhizomes and roots. In spring first the nitrogen stored in asparagine and with a delay of about three weeks that in arginine was mobilized and translocated to the rapidly growing shoots. Proteins may function as nitrogen store too, in particular in the case of the seeds. In the below ground organs, however, a special storage protein, rich in amides and/or arginine, which would correspond to the large quantities of these amino acids in the overwintering organs, could not be detected.