The metabolism of Dhurrin in Sorghum seedlings 1: Distribution, biosynthetic site and function

Abstract

The variation of dhurrin in various parts of sorghum seedlings was monitored over a period of 28 days. The results showed that a peak of 2.8 umol was reached in the shoot on the 8th day while in the root, it was only 0.24 umol on the 7th day. Dhurrin concentration reduced with age and size of seedlings.

Labelling studies with ¹⁴ C-shikimic acid showed that all the tissues synthesized and stored dhurrin; above 90% of the radioactivity was found in the dhurrin of the root. Different parts of sorghum seedlings showed ability to synthesize dhurrin from ¹⁴ C-tvrosine. In vitro synthesis of dhurrin by microsomal fractions of the different parts also confirmed this.

Analysis of the dhurrin content of the first, second and third leaves showed a fair distribution in the first leaf. The second and third leaves however showed a gradient from the apex to the stalk.

The results are discussed on the basis of dhurrin distribution, biosynthetic capability of the parts and function.