Award details

Regulation and genetic manipulation of gibberellin biosynthesis

Reference	BBS/E/C/00803290
Principal Investigator / Supervisor	Dr John Lenton
Co-Investigators / Co-Supervisors
Institution	Rothamsted Research
Department	Rothamsted Research Department
Funding type	Research
Value (£)	301,325
Status	Completed
Type	Institute Project
Start date	01/04/1997
End date	31/03/1999
Duration	24 months

Abstract

Gibberellins (GAs) are potent regulators of stem extension and other developmental processes, such as the production of hydrolytic enzymes in germinating cereals and in fruit set and growth. The aim of this project is to determine how GA concentration is regulated within plants. Attention is focused on metabolic regulation of the GA biosynthetic pathway, tissue specificity and developmental regulation, as well as on the effects of environmental factors such as light quality, photoperiod and temperature. Dwarf mutants that are either deficient in GA production or in the ability to respond to GAs are being characterised. On the basis of detailed analyses of the GA status of such mutants, we have proposed that GA action in normal plants results in down- regulation of certain enzymes on the pathway to GA1. This hypothesis will be tested using cDNA clones and antibodies for different GA biosynthesis enzymes. Transgenic plants, in which genes for specific GA- biosynthetic enzymes are either overexpressed or their expression is repressed by 'antisense' technology, will be used to determine the consequences of perturbing flux through the pathway, in order that rate-limiting and regulatory steps can be identified. Objectives 1996 Determine contribution of different tissues to GA content of expanding internodes in pea by examining GA metabolism in, and GA transport from, leaves, stipules and internodes. Isolation of the GA3/7-forming enzyme from seeds of Marah macrocarpus and determination of the endogenous GAs and enzyme activities for GA-biosynthesis in endosperm and embryos using cell-free preparations. Metabolic studies on GA biosynthesis will be continued to investigate the possibility of GA9, dehydroGA9 and GA7 being precursors of GA3 in maize seedlings and to determine the individual steps of GA-biosynthesis in Arabidopsis and rice seedlings. Complete determination of GA- biosynthetic pathway in germinating wheat. Quantify GAs in transgenic Arabidopsis expressing different GA 20-oxidase constructs. 1997 The influence of the Rht3 gene on expression of GA 20-oxidase genes in wheat will be determined using sequence specific probes and RT-PCR. The effect of GA response on 20-oxidase expression in arabidopsis will be studied using the At2301-GUS and At2353-GUS lines. The effects on protein levels will be determined using antibodies. The GA content of arabidopsis plants overexpressing a MYB gene (dwarfed) or the DNA-binding domain (slender) will be determined.

Summary

unavailable

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search