TRANSLOCATION OF C14-LABELLED AMINO ACIDS AND AMIDES IN THE STEMS OF YOUNG SOYBEAN PLANTS

Abstract

Translocation of each of seven amino acids and three amides was measured for periods of 5 minutes or less after introduction through the cut petiole of a primary leaf. The compounds used were asparagine, urea, glutamic acid, glutamine, glycine, norleucine, arginine, serine, alanine, and aspartic acid. During the short times of these experiments it was found that each compound was translocated downward as such. The amount of carbon-14 in the stem decreased logarithmically from the point of introduction. Each compound was translocated with unchanged velocity past a short section of stem killed with steam. There was no translocation of aspartic acid through a stem that had an entire internode killed with steam. Potassium cyanide (10⁻² M) did not inhibit the velocity of translocation of any of the compounds although the logarithmic pattern of distribution of arginine was altered. The minimum velocity of translocation was different for each compound and varied between 350 cm per hour for asparagine and 1400 cm per hour for aspartic acid.