Project 6 - Coordination of Gene Expression and Enzyme Activity during Differentiation in Developing Cereal Grains

1.Planned Outcome/Aims

The aim of this project is to apply the knowledge and technologies generated in Projects 1 and 2 to address more complex areas in cereal development, namely the differentiating endosperm in developing grain.  In cereals, the starchy endosperm of the grain is the major site for the deposition of storage polymers that will support seedling growth following germination.  Cellularization of the starchy endosperm early in grain development involves ‘atypical’ growth of cell walls around individual nuclei in a multinucleate syncytium.  In this project the genes and enzymes responsible for the coordination of wall synthesis will be defined, together with the changes that occur during aleurone differentiation and during programmed cell death of the starchy endosperm in mature grain.

2. Contracted Outputs

This Project will be commenced in the first year, but activities will increase as results and techniques generated in Projects 6 and 7 become available.  The specific outputs anticipated are:

• Development of expression profiles for genes and proteins responsible for wall synthesis in developing barley endosperm
• Demonstration of how genes and enzymes are coordinated in complex differentiating systems
• Identification of key regulatory genes involved in wall synthesis.

3. Research Methodology

Identification of genes expressed during differentiation:  The techniques will be essentially as described for the other Projects.  Proteomics and microarrays will be used to identify mRNA and protein populations present in whole, and dissected tissues.  Differentially expressed genes and proteins, together with those expressed in response to phytohormone treatment or environmental factors, will be analysed through in situ hybridization and various transgenic procedures.  Mutant lines will be screened for lesions in these genes.  In the proposal ‘Gene Discovery in Wheat and Barley’, Professor Langridge will develop EST libraries and microarrays from endosperm in the early stages of development.  Here, we plan to focus our attention on the later stages of grain maturation.  Again, the Programs are seen to be complementary and synergistic with respect to the greatly enhanced level of understanding of grain development that might be achieved.

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