Abstract
Upward and lateral movements of 14C-amino compounds in intact trees and excised shoots, and upward translocation of major amino compounds in intact shoots were examined in the early stage of new shoot development. The results were summarized as follows.
1. Uniformly 14C-labelled arginine, asparagine, aspartic acid and proline were steadily taken up by roots of intact trees, translocated to old leaves and new shoots, and appeared in the fed compound and its metabolized products in these organs.
2. 14C-arginine, asparagine and proline were translocated upward not only via the xylem but also via the phloem. Lateral movements, from the xylem to the phloem and from the phloem to the xylem, also occurred. These compounds showed different patterns in their movements. 14C-arginine and its metabolic products tended to accumulate in the xylem and translocate upward in the xylem. This was in contrast to 14C-proline and its metabolic products, which tended to accumulate in the phloem and translocate upward in the phloem. These findings were supported by the results obtained in intact shoots.
3. The 14C-amino compounds were metabolized to soluble and insoluble compounds during the translocation and in the new shoots. However, they differed significantly in the extent of metabolic conversion during translocation; proline was hardly metabolized, arginine and asparagine were moderately metabolized, and aspartic acid was almost completely metabolized.
