The Role of Auxin and Abscisic Acid in the Induction of Cell Division in Jerusalem Artichoke Tuber Tissue Cultured in vitro
Abstract
This paper deals with two specific questions with respect to the role of auxin and abscisic acid in the induction and promotion, respectively, of DNA synthesis in tuber tissue of Jerusalem artichoke (Helianthus tuberosus). The first of the question concerns with the need of an auxin during first few hrs of the wound response in the tissue, for induction of DNA synthesis and cell division. The second of the questions relates to the need for the simultaneous presence of NAA and ABA for the promotion of auxin-induced DNA replication. Evidence is presented here to show that a pre-incubation of the explants in the absence of auxin neither affects the duration of the lag period observed when auxin is provided, nor does it affect the number of cells/explant that respond to auxin at the later stage. If the tuber explants are pre-incubated in the absence of a hormone for 12 hrs before transfer to medium containing NAA, the synthesis of DNA does not commence until after the tissue has been in contact with the auxin for a time equal to the total duration of the lag period. The peak of DNA synthesis is also delayed by about 12 hrs in these explants as compared to the controls.
While an auxin is required during the whole length of the lag period for the induction of DNA replication, it does not seem to be true of ABA for the promotion of auxin-induced DNA replication. When the explants are pre-incubated in NAA (1 mg/1) for 12 hrs and then transferred to NAA + ABA, the rates of 3H-thymidine incorporation at different times during the S period are quite comparable with those grown in a mixture of NAA + ABA from the very beginning.
On the basis of the data presented here, it is suggested that auxin acts on about 60–70% of the cells in the explant to initiate a sequence of events that can eventually lead to DNA synthesis in these cells. But only about half of these cells (about 30–35% of the total cell population) actually undergo DNA synthesis, while the other half are somehow inhibited from doing so. Abscisic acid if given from the beginning or just before the initiation of DNA replication, somehow overcomes this inhibition and as a result all of the auxin-activated cells enter the S phase.
Department
Biological Sciences
Publication Date
7-1-1979
Journal Title
Zeitschrift für Pflanzenphysiologie
Publisher
Elsevier BV
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Subhash C. Minocha, The Role of Auxin and Abscisic Acid in the Induction of Cell Division in Jerusalem Artichoke Tuber Tissue Cultured in vitro, Zeitschrift für Pflanzenphysiologie, Volume 92, Issue 5, 1979, Pages 431-441, ISSN 0044-328X, https://doi.org/10.1016/S0044-328X(79)80188-9
Rights
Copyright © 1979 Gustav Fischer Verlag, Stuttgart. Published by Elsevier GmbH All rights reserved.