Evidence for a gravity-regulated level of endogenous auxin controlling cell elongation and ethylene production during geotropic bending in grass nodes

Wright, M. and Mousdale, D.M.A. and Osborne, D.J. (1978) Evidence for a gravity-regulated level of endogenous auxin controlling cell elongation and ethylene production during geotropic bending in grass nodes. Biochemie und Physiologie der Pflanzen, 172 (6). pp. 581-596.

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Abstract

Experiments are described which indicate that the geotropic bending in the node of the flowering stalk of Echinochloa colonum results from a gravity regulation of endogenous IAA levels within the leaf sheath base. When an intact or longitudinally halved node was placed horizontally, elongation was initiated in cells of the lower sides of the leaf sheath base and was preceded by a rise in the levels of extractable IAA. These events were followed by an increased rate of ethylene production. In stem halves in the upper position IAA content declined and ethylene production remained low. When halved nodes were reorientated from upper to lower or lower to upper positions IAA levels rose or fell, cell elongation was initiated or repressed and ethylene production increased or decreased, resp. Addition or depletion of ambient ethylene or addition of the analogue of rhizobitoxin to repress ethylene production did not modify the geotropic bending response. Over a range of conc., IAA application enhanced elongation of nodal tissue in the vertical or upper position but inhibited or had no effect on elongation of lower sides. The results were discussed in relation to the Cholodny-Went hypothesis of geotropism. It was concluded that particular orientations of the leaf sheath base with respect to the gravity vector evoked rapid and highly localized changes in auxin metabolism, and the ensuing rises and falls in IAA levels control the initiation and repression of cell elongation

Item Type:	Article
Author Affiliation:	ARC Unit of Developmental Bot., Cambridge CB3 0DY, UK
Subjects:	Plant Protection > Pesticides Plant Physiology and Biochemistry > Plant Physiology Plant Physiology and Biochemistry > Biochemistry
Divisions:	Other Crops
Depositing User:	Ms K Syamalamba
Date Deposited:	02 May 2012 10:23
Last Modified:	02 May 2012 10:23
URI:	http://eprints.icrisat.ac.in/id/eprint/5048

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