This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (108) Citing Articles via Google Scholar Google Scholar Articles by Kojima, M. Articles by Conn, E. E. Search for Related Content PubMed PubMed Citation Articles by Kojima, M. Articles by Conn, E. E. Agricola Articles by Kojima, M. Articles by Conn, E. E.

Articles

Tissue Distributions of Dhurrin and of Enzymes Involved in Its Metabolism in Leaves of Sorghum bicolor¹

^a Department of Biochemistry and Biophysics, University of California, Davis, California 95616

The tissue distributions of dhurrin [p-hydroxy-(S)-mandelonitrile--D-glucoside] and of enzymes involved in its metabolism have been investigated in leaf blades of light-grown Sorghum bicolor seedlings. Enzymic digestion of these leaves using cellulase has enabled preparations of epidermal and mesophyll protoplasts and bundle sheath strands to be isolated with only minor cross-contamination. Dhurrin was located entirely in the epidermal layers of the leaf blade, whereas the two enzymes responsible for its catabolism, namely dhurrin -glucosidase and hydroxynitrile lyase, resided almost exclusively in the mesophyll tissue. The final enzyme of dhurrin biosynthesis, uridine diphosphate glucose:p-hydroxymandelonitrile glucosyltransferase, was found in both mesophyll (32% of the total activity of the leaf blade) and epidermal (68%) tissues. The bundle sheath strands did not contain significant amounts of dhurrin or of these enzymes. It was concluded that the separation of dhurrin and its catabolic enzymes in different tissues prevents its large scale hydrolysis under normal physiological conditions. The well documented production of HCN (cyanogenesis), which occurs rapidly on crushing Sorghum leaves, would be expected to proceed when the contents of the ruptured epidermal and mesophyll cells are allowed to mix.

¹ This work was supported in part by National Science Foundation Grant PCM 77-25769 and National Institutes of Health Grant GM-05301-21.

This article has been cited by other articles:

				R. Shroff, F. Vergara, A. Muck, A. Svatos, and J. Gershenzon Nonuniform distribution of glucosinolates in Arabidopsis thaliana leaves has important consequences for plant defense PNAS, April 22, 2008; 105(16): 6196 - 6201. [Abstract] [Full Text] [PDF]

				Y. O. Ahn, H. Saino, M. Mizutani, B.-i. Shimizu, and K. Sakata Vicianin Hydrolase is a Novel Cyanogenic {beta}-Glycosidase Specific to {beta}-Vicianoside (6-O-{alpha}-L-Arabinopyranosyl-{beta}-D-Glucopyranoside) in Seeds of Vicia angustifolia Plant Cell Physiol., July 1, 2007; 48(7): 938 - 947. [Abstract] [Full Text] [PDF]

				R. E. MILLER, R. JENSEN, and I. E. WOODROW Frequency of Cyanogenesis in Tropical Rainforests of Far North Queensland, Australia Ann. Bot., June 1, 2006; 97(6): 1017 - 1044. [Abstract] [Full Text] [PDF]

				M. Cicek and A. Esen Structure and Expression of a Dhurrinase (beta -Glucosidase) from Sorghum Plant Physiology, April 1, 1998; 116(4): 1469 - 1478. [Abstract] [Full Text]