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Seed development in Phaseolus vulgaris L. cv. Seminole. 3. NMR imaging of embryos during ethylene-induced precocious germination

Published online by Cambridge University Press:  19 September 2008

David W. Fountain ,
Lucy C. Forde ,
Edwin E. Smith ,
Karen R. Owens ,
Donald G. Bailey  and
Paul T. Callaghan
David W. Fountain*
Affiliation:
Department of Plant Biology and Biotechnology, Massey University, Palmerston North, New Zealand
Lucy C. Forde
Affiliation:
Department of Physics, Massey University, Palmerston North, New Zealand
Edwin E. Smith
Affiliation:
Department of Plant Biology and Biotechnology, Massey University, Palmerston North, New Zealand
Karen R. Owens
Affiliation:
Department of Physics, Massey University, Palmerston North, New Zealand
Donald G. Bailey
Affiliation:
Department of Physics, Massey University, Palmerston North, New Zealand
Paul T. Callaghan
Affiliation:
Department of Physics, Massey University, Palmerston North, New Zealand
*
*: Fax: 64 06 3505694 E-mail [email protected]
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Abstract

Embryos taken from late maturation phase seeds of Phaseolus vulgaris cv. Seminole prior to seed desiccation (35–45 DAA) can be induced to germinate in the absence of water by exogenous ethylene. NMR imaging of proton relaxation within the embryo shows changes in water status in putative (and not fully differentiated) vascular tissues of the hypocotyl within 3 h of ethylene administration. Difference imaging revealed that the change was progressive in the hypocotyl towards the radicle tip and was accompanied by changes in water status in the cotyledons. Water within plumular leaves was also affected. Increase in diameter of the hypocotyl–radicle axis (as estimated by pixel counts) was detectable from 3 h. Longitudinal radicle growth was detectable by NMR imaging at 18 h. Visible germination under the conditions used was apparent after 20 h. Changes in water status detected by this technique are an indication of changes in activity (concentration) or motion of water molecules or both. The data are consistent with a mode of action of ethylene in stimulating a redistribution of water within embryo structures from cotyledons to axis via the cotyledonary node and allowing the axis access to water sufficient to support germination. This supports the hypothesis that in vivo, quiescence at this developmental stage is induced and maintained by sequestration of water within the cotyledons.

Keywords

ethylenenuclear magnetic resonance imagingPhaseolusprecocious germinationwater imagingwater redistribution
Type
Physiology & Biochemistry
Information
Seed Science Research , Volume 8 , Issue 3 , September 1998 , pp. 357 - 365
Copyright
Copyright © Cambridge University Press 1998

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