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.

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: https://theses.gla.ac.uk/id/eprint/76695