IGF Maize

Maize Functional Genomics

The Maize genome is relatively complex due both to its ancient allotetraploid origins and the presence of large numbers of transposable elements. However, these features actually enhance its suitability for functional studies. The number and variety of transposable elements facilitate insertional mutagenesis programs, while its allotetraploid based gene redundancy allows the characterisation of mutants which may be lethal in a diploid species. Transposons were first identified in maize in the late 1940s by Barbara McClintock as mobile pieces of the genetic material acting as mutable elements. More recently, the Mutator family of transposable elements have become versatile tools for maize gene mutagenesis because they are present in high copy number (10-100) and insert preferentially within and around genes. We have produced a variety of transposon mutagenesis resources based on Robertson's Mutator (Mu) transposable elements. In 1998, we developed a classic PCR screen for mutants within known maize genes. This has now been superseded by the MuArray which rapidly identifies mutant plants through hybridisation with a fluorescently labelled gene of interest. We have also developed a high throughput screen, MuID, to identify large numbers of plants with mutations within genes expressed during specific developmental stages. MuArray and MuID are both based on the MuAFLP method for the amplification of transposon insertion flanking sequences from individual maize plants. Over 700 such amplified insertion sequences are available on a blast searchable database MuDB and seed harbouring these insertion events is available on request. These screens are complemented by technology such as fluorescent MuAFLP, gene expression microarrays and a range of biochemical, physiological and molecular tools for the characterisation of mutant plants. Alongside functional genomic programs, several maize structural genomic projects are underway using molecular markers and large insert genomic libraries to examine gene duplication and divergence. Single Nucleotide Polymorphisms (SNPs) are the current marker of choice due to their high abundance and ease of high throughput detection. Using bioinformatics tools to mine expressed sequence databases, we have identified over 10,000 putative SNPs, in maize. These SNPs are available online at the maize SNP database.

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Maintained by Gary Barker Last updated Dec 2001