Award details

Starch granule and polymer initiation

Reference	BB/C517309/1
Principal Investigator / Supervisor	Dr Kay Trafford
Co-Investigators / Co-Supervisors
Institution	John Innes Centre
Department	Metabolic Biology
Funding type	Research
Value (£)	268,265
Status	Completed
Type	Research Grant
Start date	19/09/2005
End date	18/09/2008
Duration	36 months

Abstract

The aim of this work is to discover how starch granules and amylopectin molecules are initiated. A range of approaches and plant material will be used: 1) We will use an open-ended approach to characterise the nature of the hilum of starch granules and identify any associated initiation factors. This will involve MUDPIT analysis of the associated proteins and characterisation of the glucans within the hilum. We will use a transgenic line of potato that makes extremely small starch granules for this work. Very small granules will be enriched in glucans and proteins composing the hilum relative to larger granules. 2) We will investigate the roles of the genes in Arabidopsis and rice encoding proteins similar to glycogenin using a reverse genetics approach. Insertional mutant lines for each of the five arabidopsis genes have already been obtained and homozygous mutant lines selected. Double and triple mutant lines are being selected. RNAi has been used to decrease the expression of glycogenin-like proteins in arabidopsis and wheat. Transgenic lines of Arabidopsis, barley and wheat over-expressing this glycogenin-like gene will also be analysed. The starch content, composition and morphology in the leaves of these mutant and transgenic plants will be determined. Rice insertional mutants will be obtained and analysed in a similar manner. 3) In an independent biochemical approach, we have identified two proteins with glycogenin-like activity and shown these to be located within the starch granules of many plant organs. These proteins are glucosylated in the presence of ADPglucose. To identify the genes encoding these proteins, we will purify the proteins from rice endosperm and obtain protein sequence. The genes encoding these proteins will be compared to the glycogenin-like genes described in (2). If the glucosylated proteins in starch are encoded by the glycogenin-like genes, we will use the glucosylation assay to study the transgenic and mutant lines described above. We will also investigate the mechanism of action of these potential primers to determine whether they are involved in the initiation of starch polymers or starch granules or both of these. If novel proteins are identified, we will investigate their roles using a reverse genetic approach.

Summary

unavailable

Committee	Closed Committee - Agri-food (AF)
Research Topics	Crop Science, Plant Science
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

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