Award details

A novel microinduction system in Arabidopsis to test the function of the cell wall protein expansin in leaf growth and development

Reference	BB/C513485/1
Principal Investigator / Supervisor	Professor Andrew James Fleming
Co-Investigators / Co-Supervisors
Institution	University of Sheffield
Department	Animal and Plant Sciences
Funding type	Research
Value (£)	125,585
Status	Completed
Type	Research Grant
Start date	01/04/2005
End date	31/03/2007
Duration	24 months

Abstract

The targeted misexpression of genes in selected groups of cells within an organism is a key approach in the investigation of gene function. However, the tools available to do this are still limited. This problem is compounded in the common situation where a protein of interest is encoded by a family of genes which show disparate yet overlapping patterns of gene expression. A case in point is the expansin family of cell wall proteins in plants. Various lines of evidence indicate that expansins play a key role in regulating cell wall architecture and that, as a consequence, they play a major role in the control of plant growth. However, decisive evidence linking ablation of expansin gene expression to specific altered growth phenotype is lacking. This lack of evidence is linked to the fact that expansins are encoded by a large gene family, with the problems of functional redundancy that this entails. In the proposed research, we will develop a novel technique to suppress gene expression in local regions of Arabidopsis using a microinduction approach developed in our laboratory. This approach allows the generation of visualisable genetic chimeras in very young developing leaf primordial. Linking this approach to RNAi-based suppression of gene expression will allow us to target the down-regulation of expression of specific genes within defined sectors of an otherwise genetically identical organ. Our data (based on expression analysis of expansin genes in dissected, staged leaf primordia) indicate that at the earliest stages of leaf development only three expansin genes are expressed. Two of these genes are highly similar at the nucleotide sequence and expression of both these genes should be suppressed by a single RNAi construct. We will express this construct in a genetic background in which the third young leaf- expressed expansin gene contains a transposon-insertion, thus abrogating gene expression. Thus, microinduction of the RNAi construct in the context of the young leaves in this genetic background should prevent expression of all three expansin genes normally associated with this phase of development. We will examine whether suppression of expansin gene expression leads to altered growth in young leaf primordial, thus testing the hypothesis that expansins are required for normal leaf growth. A molecular comparison of induced and non-induced sectors will also be performed to investigate whether suppression of specific expansin genes influences the expression of other members of this gene family, ie. whether the family acts as a gene network. In addition to providing key data on a cell wall protein implicated in many aspects of plant growth, our experiments will develop a new tool for the analysis of gene function in Arabidopsis. In particular, the ability to generate sectors of tissue expressing (or suppressing) particular genes will offer novel ways of investigating intercellular signalling pathways over both long and short distances in plants. The investigation of such pathways is a major challenge in plant biology.

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

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