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Dr Pierre Sourdille seminar

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Seminar
12 February 2013, 11am
at the James Hutton Institute, Dundee
for scientists, researchers and other interested parties
Pierre Sourdille

Dr Pierre Sourdille, French National Institute for Agricultural Research (INRA), will give a seminar entitled "Recombination in bread wheat: lessons from chromosome 3B" at the James Hutton Institute in Dundee. Note: This seminar will not be broadcast to the Aberdeen site.

Abstract

Meiotic recombination is a complex process that remains poorly understood in plants. It starts with numerous (sometime hundreds/chromosome) double-strand breaks of the chromosomes which are rarely converted in crossing-overs (COs) events which lead to allele admixture. Moreover, the COs are not evenly distributed along the chromosomes and they mainly occur in small regions of a few base-pairs called recombination hot-spots. If recombination hot-spots are well studied in human, drosophila or yeast, this is not the case in plants. In model species such as arabidopsis or rice, COs are distributed all along the chromosomes except in the close vicinity of the centromeres.

In wheat, meiotic recombination is restricted to the distal parts of the chromosomes and about one third of the chromosomes around the centromeres are totality deprived of COs. However, pericentromeric regions contain a lot of genes and the absence of COs prevents thus the introduction of new alleles originating from exotic or wild varieties at these genes or the admixture of the most favourable alleles at different genes since the combinations are fixed due to absence of possible recombination. Increasing recombination in these regions is thus of main importance to develop new varieties that will meet the challenges of increasing the yields under growing constraints (low inputs, global warming and reduction of arable lands).

Our aim is to study the recombination at the functional and structural levels. At the functional level, we studied a set of ~20 genes known to play a role in the meiotic recombination pathway in arabidopsis. We evaluated their pattern of loss/retention in polyploid species and tested the variation of expression of the different homoeologous copies. Identification of mutants is underway. From the structural point of view, we are currently studying the distribution of COs along the chromosome 3B which is used as a model. We genetically mapped ~2000 SNPs and we identified a set of recombination hot-spots. We are currently correlating the recombination rates at these spots with the sequence features such as coding or repeated sequences, GC percentage, etc. Impact of pairing genes located on chromosome 3B is also evaluated.

Biography

Pierre started his career in 1989 in the Limagrain group (Biogemma laboratory) where he realised his masters. He contributed to demonstrate the power of the molecular markers for variety identification and the structuring of the collections in maize. Then he gained his PhD on the use of the molecular markers on this same species to study the genetic diversity and for the detection of loci involved in the expression of a quantitative trait (QTL), the earliness. This work evolved in marker assisted selection of ideotypes including a maximum of the most favorable loci without loss of yield.

After his PhD, Pierre integrated Agrogene where he was in charge of setting up the molecular marker lab and of the production and analysis of the data. He joined INRA in 1995 where he initially coordinated the programmes for QTL identification for agronomic traits such as earliness, plant height, spike morphology and disease resistance. To achieve this goal, he developed saturated genetic maps to identify the most relevant QTL. To be more efficient, he coordinated two different projects aiming at the development of SSRs derived either from genomic or expressed (EST) sequences. This resulted in the release in the public databases of ~2000 SSRs that were widely used by the whole wheat community. In order to go toward the positional cloning of the genes underlying the QTLs, PS participated to the elaboration of the first chromosome-specific physical map in wheat, the chromosome 3B. This chromosome is currently being sequenced and the first fully annotated and genetically anchored sequence of one wheat chromosome should be published beginning of 2013.

Finally, Pierre benefited from the establishment of the physical map and of the sequence to develop in the same time an original and still under-explored research project in bread wheat: the analysis of the meiotic recombination. He is supervising research on distribution and regulation of crossover events and their relationships with sequence features such as gene density, expression, physical constraints of the chromatin, etc. He is also studying the functioning as well as the variability of the genes involved in this process to improve the recombination, especially around the centromeres.

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The James Hutton Research Institute is the result of the merger in April 2011 of MLURI and SCRI. This merger formed a new powerhouse for research into food, land use, and climate change.