Gibberellin metabolism in seeds and seedlings of the runner bean, Phaseolus coccineus L

Malcolm, Joan Margaret (1988) Gibberellin metabolism in seeds and seedlings of the runner bean, Phaseolus coccineus L. PhD thesis, University of Glasgow.

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Abstract

An investigation was made of GA metabolism in Phaseolus coccineus L., cv. Prizewinner using an in vitro preparation from immature seeds. GA12-aldehyde underwent non-13-hydroxylated conversion to GA4 via GA12, GA15, GA24, GA36 and GA37 and was metabolised to GA1 via a 13-hydroxylated pathway encompassing GA19, GA20, GA44 and GA53. GAa was not 13-hydroxylated to produce GA1. Key incubations were performed using an in vitro preparation from immature seeds of a dwarf variety, Hammonds Dwarf Scarlet, but no metabolic differences were observed between dwarf and tall cultivars. GA1 was not 2P-hydroxylated to form GA8. The nature of the 3p-hydroxylating enzyme from immature seeds was investigated by fast protein liquid chromatography (FPLC) separation of the crude cell-free preparations from Prizewinner and Hammonds Dwarf Scarlet Following assay of the FPLC fractions, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of zones which converted [3H]GA20 to [3H]GA1 was carried out. Preliminary analysis revealed similarities between the polypeptides of both cultivars. In order to investigate GA metabolism in seedlings, [3H]-labelled GAs were applied to cvs. Prizewinner and Hammonds Dwarf Scarlet. In contrast to metabolism by the cell-free preparations from immature seeds, [3H]GA4 as well as [3H]GA20 was converted to [3H]GA1 which was further converted to [3H]GA8, in seedlings of each variety. It was concluded that the dwarf growth habit exhibited by seedlings of Hammonds Dwarf Scarlet was not simply a consequence of an inability to synthesise GA1. A study of the endogenous GA20 content of the dwarf and tall seedlings showed mean values of 1.14 ng g-1 fresh weight and 0.95 ng g-1 fresh weight, respectively.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Plant sciences, Botany
Date of Award: 1988
Depositing User: Enlighten Team
Unique ID: glathesis:1988-76695
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 13:53
Last Modified: 19 Nov 2019 13:53
URI: http://theses.gla.ac.uk/id/eprint/76695

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