The metabolism of fumarate by peach, apple and privet roots

Abstract

Excised roots of peach, apple and privet respired the bulk (40–73%) of absorbed fumarate-1,4- 14C to CO 2 by 320 min. On the other hand, only 12% of the absorbed fumarate-2,3- 14C was respired to CO 2 by peach roots, while privet roots converted less than 1%. The fate of fumarate-2,3- 14C was greatly dissimilar among the three species; peach roots incorporated 50% of the absorbed label into protein, apple 33% and privet 10%. Privet roots contained the most, and peach roots the least, 14C in organic acids. The rapid metabolism of fumarate-2,3- 14C to glutamate and aspartate and the large incorporation of these amino acids into protein by the three species indicates the presence of enzyme systems important in amino acid synthesis in the roots of woody plants, and the labelling pattern suggests that aspartase is not physiologically important in these tissues.