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Functional significance of clustering of genes for the tissue-specific synthesis of defence-related secondary metabolites in cereals

Reference	BB/C504435/1
Principal Investigator / Supervisor	Professor Anne Osbourn
Co-Investigators / Co-Supervisors	Professor Peter Shaw, Ms Eva Wegel
Institution	University of East Anglia
Department	Sainsbury Laboratory
Funding type	Research
Value (£)	224,248
Status	Completed
Type	Research Grant
Start date	15/01/2005
End date	14/01/2008
Duration	36 months

Abstract

Avenacins are antimicrobial triterpenoid saponins that are produced in oat roots. Our evidence indicates that genes for biochemically distinct steps in avenacin biosynthesis are clustered in the oat genome. This is one of only two known gene clusters for secondary metabolism in plants so far, although several such clusters are known in fungi. This finding raises important questions concerning the corregulation of the clustered genes and whether clustering is a widespread feature of genomic organisation in plants. We have cloned the gene encoding oat beta-amyrin synthase (Sad1), the enzyme that catalyses the first committed step in avenacin synthesis and are sequencing up to 1Mb of the region encompassing this gene as part of a complementary project. We have also cloned a Sad2 candidate (AsCypA), which is about 100Kb from Sad1 and is predicted to encode a novel cytochrome P450. In this project we will investigate the epigenetic regulation of genes within this region in avenacin producing and non-producing tissues. We will use a combination of biochemical and structural methods to characterise histone and DNA modifications that accompany transcriptional regulation, including chromatin immunoprecipitation and a novel fluorescence in situ hybridisation method applied to chromatin fibres. We will also determine whether transcriptional activation is accompanied by 3-dimensional changes in the nuclear localisation of the genes under investigation using confocal microscopy. Initial experiments will focus on Sad1 and AsCypA along with reference genes outside the region. Further Sad gene candidates within the cluster will be identified from the BAC sequence output and subjected to expression analysis. We will then extend the investigation of epigenetic regulation and organisational changes to genes emerging from this analysis. This is a multidisciplinary project that brings together chromosome and nuclear biology and bioimaging with the integrated approaches used by the Osbourn to address an important question 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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