A STUDY OF THE DISTRIBUTION OF CARBON-14 LABELLED COMPOUNDS IN STEM RUST INFECTED WHEAT LEAVES

Abstract

Glucose-U-C¹⁴, glycine-2-C¹⁴, benzimidazole-2-C¹⁴, as well as C¹⁴O₂, were fed to rusted leaves of Little Club wheat. Radioautographs of whole leaves gave similar results to those of previous investigators, indicating greater radioactivity in rust ed tissue sections. However, when quantitative measurements were made the results indicated that rusted tissue sections do not contain more radioactivity than the healthy tissue sections despite the apparent accumulation of labelled com pounds at infection sites indicated by radioautographs of the treated leaves. The apparent accumulation of radioactivity at the infection sites of rusted leaves may not, therefore, represent the actual concentration of the labelled compounds throughout the infected leaf. The phenomenon of radioactivity accumulation indicated by radioautographs may be attributed to two factors: (a) the geometric factor in respect to radioactive sources to the X-ray film and (b) the specific distribution in respect to the higher radioactivity in the rapidly growing regions of the fungus.