You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Molecular Basis of Auxin-Regulated Extension Growth and Role of Dextranase
Anton N. J. Heyn
Proceedings of the National Academy of Sciences of the United States of America
Vol. 78, No. 11, [Part 2: Biological Sciences] (Nov., 1981), pp. 6608-6612
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/11312
Page Count: 5
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
The first step in the extension growth of the plant cell is a process in which the cell wall becomes ductile or plastic, after which the actual enlargement takes place passively under the influence of turgor. The nature of this process has not been explained, although much research has been carried out concerning it. In the present report, it is shown that a specific enzyme, which is identical or nearly so with dextranase (α -1,6-D-glucan 6-glucanohydrolase, EC 22.214.171.124) and is associated with the cell walls of growing coleoptiles, plays a prominent role in this process. The action of this enzyme is dependent on the level of growth hormone, auxin, in the tissue. Under its action, certain cell wall components are broken down to yield arabinose and glucose. These sugars are also released during autolysis of cell wall material. The molecular linkages broken in the process are probably the arabinogalactan crosslinks of the hemicellulose matrix, which are the main constituents of the wall containing arabinose. This is substantiated by the finding that dextranase can break down arabinan and compounds containing arabinose chains with the release of arabinose, just as in the action of the enzyme on the wall. The breaking of these crosslinks will impart the necessary plasticity to the wall for cell extension to occur.
Proceedings of the National Academy of Sciences of the United States of America © 1981 National Academy of Sciences