Trude Schwarzacher PI

schwarz.jpgDr Trude Schwarzacher is a co-project leader of the Molecular Cytogenetics research group in the University of Leicester.

Current research interests include:

Wheat and related species

I am studying introgression of alien chromosomes and introgression of alien chromosomes from wild species into bread wheat. In wheat and related species, we have found differences in cytosine methylation patterns at symmetrical and asymmetrical sites in the tandemly repeated 120bp repeat DNA family in diploid and polyploid genomes and we are currently investigating whether other repetitive DNA families show similar changes.

On the chromosomal level, diploid species of rye and wheat show uniform methylation patterns while allopolyploids have more unevenly distributed methylation indicating de novo methylation and demethylation mechanisms when genomes are combined in polyploid and hybrid species. In wheat breeding lines, incorporating alien chromatin segments important to understand such epigenetic changes both at the DNA sequence level and the global chromatin level to predict the successful

Genome organisation and epigenetic mechanisms in polyploid plant species
Most estimates suggest that 50% of plant species are recognisable and evolutionary recent polyploids where diploid ancestors can be identified. My lab is studying the interaction of genomes, chromosomes and DNA sequences in polyploids and hybrids in several plant groups including cereals, petunia, banana and others.

My work concentrates on repetitive DNA sequences, both tandemly repeated satellite sequences and dispersed transposable elements, their diversity and evolution, as well as their epigenetics as evidenced by chromatin organisation and methylation. We speculated that it is the biological significance of epigenetic phenomena that have lead to the successful evolutionary history of polyploidy and hybrid plant species.

Pararetroviruses
In a recent European collaboration (PARADIGM) we have studied genomic integration of pararetroviruses that are a recently discovered repetitive sequences class in plants, and which in petunia and tomato form a significant part of the genome. They possibly show a much wider distribution in plant genomes, but are often degenerate and rearranged. We have recent evidence for pararetrovirus elements in sugar beet and other angiosperms and are in the process of sequencing full elements.

Pararetroviruses are closely related to pseudoviridae retroelements and are often found in their physical proximity. Pararetrovirus activation is linked to disease outbreaks and patterns of DNA and chromatin methylation and possibly epigenetic silencing mechanisms. Activation of integrated, but dormant pararetroviruses can be caused by the introduction of wide hybridisation and can lead to disease outbreaks through tissue culture or environmental stresses as has been shown for banana.

Banana

Our studies in banana have looked at retroelements and tandemly repeated DNA sequences, and their genomic flanking sequences were studied showing differential expression, DNA and histone methylation. The close chromosomal proximity and insertion within each other postulates a possible link in the evolution of LTR-retrotransposons, tandem repeats and 5S rRNA genes, but also a role of retrotransposon sequences in gene regulation. This is supported by variable DNA methylation patterns and the presence of repeat transcripts.

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About Pat Heslop-Harrison

Professor of Molecular Cytogenetics and Cell Biology, University of Leicester Chief Editor, Annals of Botany. Research: genome evolution, breeding and biodiversity in agricultural species; the impact of agriculture; evalutation of research and advanced training.
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