Authors: Nelson, Matthew N.; Lydiate, Derek J.

Source: Genome, Volume 49, Number 3, March 2006 , pp. 230-238(9)

Publisher: NRC Research Press

Abstract:

We present clear evidence of ancestral genome triplication in Sinapis alba, a close relative of the cultivated Brassica species. Exceptionally high levels of heterozygosity in the parents of an F₁ intercross permitted the mapping of an estimated 87% of all detected restriction fragment length polymorphism (RFLP) loci, with each RFLP probe typically detecting 2 or 3 loci. These duplicated loci were arranged in 8 triplicated homologous linkage blocks and 2 small, duplicated, homologous linkage blocks covering the majority of the S. alba genome. Several large-scale inversions and translocations appear to have rearranged the order of loci within homologous blocks. The role of successive polyploidization events on the evolution of crucifer species is discussed.Key words: polyploidy, yellow mustard, Brassica hirta, genome duplication, hexaploid ancestor, paralogous loci.

Les auteurs présentent des évidences claires d'une triplication du génome ancestral chez le Sinapis alba, une espèce proche des crucifères cultivées. Des niveaux d'hétérozygotie exceptionnellement élevés chez les parents d'une population F₁ ont permis d'assigner à des groupes de liaison environ 87 % des locus RFLP (polymorphisme de longueur des fragments de restriction), chacune des sondes détectant typiquement 2 ou 3 locus. Ces locus dupliqués formaient 8 blocs de liaison homologues tripliqués et 2 petits blocs homologues dupliqués qui, ensemble, couvraient la majorité du génome du S. alba. Plusieurs grandes inversions et translocations semblent avoir modifié l'ordre des locus au sein de ces blocs homologues. Le rôle d'événements successifs de polyploïdisation dans l'évolution des crucifères est discuté.Mots clés : polyploïdie, moutarde jaune, Brassica hirta, duplication génomique, ancêtre hexaploïde, locus paralogues.[Traduit par la Rédaction]

Document Type: Research article

Publication date: 2006-03-01

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• From its inception in 1957, this international cytogenetics journal has catered to the research areas of the members of the Genetics Society of Canada; traditionally, these have included agriculture, entomology, genetics/cytogenetics, and evolutionary mechanisms. The contents of the journal have evolved as contributors developed new technologies and interests. A 20-member Editorial Board is composed of scientists from around the world. Reviews and commentary from respected experts are often featured.
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