Welcome to the ISHS Brassica 2012 Symposium

Session A-3
HOW HOMOLOGOUS RECOMBINATION IS BOOSTED IN OILSEED RAPE
Suay L. 1 , Zhang D. 1 , Eber F. 1 , Jouy H. 1 , Lodé M. 1 , Huteau V. 1 , Coriton O. 1 , Szadkowski E. 1 , Leflon
M. 2 , Martin O.C. 3 , Falque M. 3 , Jenczewski E. 4 , Paillard S. 1 , Chèvre A.M 1 *.
1
INRA, UMR 1349 IGEPP, BP 35327, F-35653 Le Rheu, France;
2
CETIOM, Avenue Lucien Brétignières, Campus de Grignon, F-78850 Thiverval Grignon, France;
3
UMR Génétique Végétale, Ferme du Moulon, Gif sur Yvette, France;
4
INRA - Institut Jean Pierre Bourgin, Route de Saint-Cyr 78026 Versailles Cedex, France.
E-mail: anne-marie.chevre@rennes.inra.fr
Selection and population bottlenecks have reduced the genetic variability within oilseed rape
(Brassica napus, AACC, 2n=38) varieties whereas a large genetic diversity is available among its
progenitors (B.rapa, AA, 2n=20 and B.oleracea, CC, 2n=18). We previously showed that it is
possible to tap into the genetic diversity of B.rapa by boosting the homologous recombination
between A genomes in AAC hybrids. This boost may be driven either by the number of C
chromosomes remaining as univalents in meiosis or by the nature of these chromosomes. To test
these alternative hypotheses, we produced AA hybrids carrying in addition 0, 1, 3, 6 or 9 univalents.
The nature of C chromosomes was determined by molecular markers and cytogenetic controls
which showed a meiotic behaviour close to the one expected. The genetic map lengths for each
hybrid were established and then compared to that of the control AA without C chromosomes in
addition. These comparisons revealed that the recombination rates were 1.4 and 2.7 times higher in
the hybrids carrying C6 or C9 alone than in the control. Furthermore, this enhancement factor
reached 3.1 and 4.1 in hybrids carrying 6 and 9 C chromosomes. Overall, the presence of C9
chromosome was the main factor affecting the recombination rate. Interestingly, we found that its
presence was also the main factor reducing crossover interference. The consequences of such results
for breeding programmes and gene cloning will be presented.
6 th International Symposium on Brassica and 18 th Crucifer Genetic Workshop - Catania (Italy) 12 - 16 November 2012
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