Studies on the Streptomycin for Plants

V. The Absorption and Translocation of S³⁵ labelled Streptomycin Sulphate in the Tobacco Plant

Abstract

The absorption and translocation of streptomycin in the tobacco plant was investigated by radioautographs of S³⁵ labelled streptomycin sulphate absorbed by the plant.
(1) It was found that there was little movement of streptomycin in the leaves when absorbed through the leaf surface. Some movement was observed towards the leaf tips when the streptomycin was applied to the mid-rib or large vein.
(2) Movement into the xylem, followed by translocation to the upper leaves, was exhibited when the streptomycin was absorbed in cotton-wool and banded around bottom of the plant stem. When the streptomycin was absorbed in large amounts, translocation to the lower leaves was slow and the higher leaves contained a larger proportion of the streptomycin, though dependent on the total amount of streptomycin absorbed in the stem, the lower leaves often contained more than the middle leaves.
(3) The results obtained from these radioautograph experiments were similar to those from the bio-assay of the leaf sap using the cup method and inoculation test with Pseudomonas tabaci.
(4) Within twenty-four hours of applying streptomycin to the lower stem, it was translocated to the upper leaves.