Translocation of ¹⁴C-L-Proline to Stems and Roots in Citrus Trees (Citrus unshiu Marc.) in Late Fall

Abstract

Proline was continuously fed in uniformly labelled ¹⁴C-form to the leaf of 4-year-old trees for 30hrs in late fall, and the ¹⁴C was analyzed in the petiole of ¹⁴C-fed leaf, other leaves, stems and roots. In the petiole, the recovered ¹⁴C as proline was accounted for 90% of the soluble ¹⁴C at the end of feeding. This demonstrates that proline exported from leaves to woody tissues in mostly unmetabolized form. The ¹⁴C was translocated partially into other leaves, but more into the stem bark and wood, and further a little into the roots. In the stem and root tissues, a part of the ¹⁴C was found in the anionic and neutral components and insoluble components. However, large parts of it remained in proline.