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The wild species Brassica fruticulosa Cyr. (FF, 2n = 16) is closely related to the cultivated Brassica species. Through interspecific reciprocal crosses between B. fruticulosa and three cultivated Brassica allotetraploids (AABB, AACC, and BBCC where A = 10, B = 8, and C = 9), four trigenomic hybrids (F.AC, 2n = 27; F.AB, 2n = 26; F.BC, 2n = 25; BC.F, 2n = 25) were produced. By chromosome doubling of respective hybrids, three allohexaploids (FF.AACC, 2n = 54; FF.AABB, 2n = 52; BBCC.FF, 2n = 50) were synthesized. In pollen mother cells (PMCs) of the trigenomic hybrids, 1-2 autosyndetic bivalents were detected within A, B, and C genomes but only one within F genome; 1-3 allosyndetic bivalents between any two genomes were observed, and a closer relationship of F and B genomes than F and A genomes or F and C genomes was revealed. The allohexaploids showed a generally low but different pollen fertilities. The chromosomes in PMCs were predominantly paired as bivalents but some univalents and multivalents at variable frequencies were observed. The bivalents of homologous pairing for each genome prevailed, but allosyndetic quadrivalents and hexavalents involving any two genomes were observed, together with autosyndetic quadrivalents for A, B, and C genomes but not the F genome. The nondiploidized cytological behaviour of these allohexaploids contributed to their low fertility. The relationships between the genome affinity and meiotic behavior in these allohexaploids were discussed. Key words: cultivated Brassica allotetraploids, Brassica fruticulosa, interspecific hybrids, autosyndesis, allosyndesis, diploidization. L'espece sauvage Brassica fruticulosa Cyr. (FF, 2n = 16) est tres apparentee aux especes cultivees du genre Brassica. Suite a des croisements interspecifiques reciproques entre le B. fruticulosa et les trois Brassica allotetraploides (AABB, AACC et BBCC oU A = 10, B = 8 et C = 9), quatre hybrides trigenomiques (F.AC, 2n = 27; F.AB, 2n = 26; F.BC, 2n = 25; BC.F, 2n = 25) ont ete produits. Suite a un doublement chromosomique chez ces hybrides, trois allohexaploides (FF.AACC, 2n = 54; FF.AABB, 2n = 52; BBCC.FF, 2n = 50) ont ete obtenus. Au sein des microsporocytes (PMC) des hybrides trigenomiques, 1-2 bivalents autosyndetiques ont ete detectes au sein des genomes A, B et C, mais un seul a ete observe pour le genome F. Un a trois bivalents allosyndetiques entre n'importe lesquels des genomes ont ete observes, et une plus grande proximite entre les genomes F et B qu'entre les genomes F et A ou F et C a ete constatee. Les allohexaploides affichaient une fertilite du pollen differente mais generalement faible. Les chromosomes dans les microsporocytes etaient principalement apparies sous forme de bivalents, bien que des univalents et des multivalents aient ete observes a des frequences variables. Les bivalents impliquant des chromosomes homologues de chaque genome etaient predominants, bien que des quadri-/hexavalents allosyndetiques impliquant deux genomes aient ete observes, de meme que des quadrivalents autosyndetiques pour les genomes A,B et C, mais pas pour le genome F. Le comportement cytologique non-diploide chez ces allohexaploides a contribue a leur faible fecondite. Les auteurs discutent des relations entre l'affinite des genomes et le comportement meiotique au sein de ces allohexaploides. Mots-cles : Brassica allotetraploides cultives, Brassica fruticulosa, hybrides interspecifiques, autosyndese, allosyndese, diploidisation. [Traduit par la Redaction], Introduction Polyploidy has played a major role in the evolution of higher plants, and polyploids have often been selected during the evolution of crop plants (Levin 2002). As now generally [...]

With the dye and medicinal plant Isatis indigotica (2n = 14) as pollen parent, intertribal sexual hybrids with Brassica napus (2n = 38, AACC) were obtained and characterized. Among a lot of F1 plants produced, only five hybrids (H1-H5) were distinguished morphologically from female B. napus parents by showing low fertility and some characters of I. indigotica, and also by having different chromosome numbers. H1-H4 had similar but variable chromosome numbers in their somatic and meiotic cells (2n = 25-30), and H5 had 2n = 19, the same number as the haploid of B. napus. GISH analysis of the cells from H1 and H5 detected one I. indigotica chromosome and one or two chromosome terminal fragments. New B. napus types with phenotypic and genomic alterations were produced by H1 after pollination by B. napus and selfing for several generations, and by H5 after selfing. A progeny plant (2n = 20) was derived from H1 after pollination by I. indigotica twice and had a phenotype similar to a certain type of B. rapa, showing that hybrid H1 likely retained all chromosomes of the A genome and lost some of the C genome in parental B. napus. The reasons for the formation of the partial hybrids with unexpected chromosomal complements and for the chromosome elimination are discussed. Key words: Brassica napus, Isatis indigotica, intertribal hybrid, genomic in situ hybridization (GISH), amplified fragment length polymorphism (AFLP), chromosome elimination. En employant la plante medicinale et tinctoriale Isatis indigotica (2n = 14) comme parent male, des hybrides sexuels inter-tribus avec le Brassica napus (2n = 38, AACC) ont ete obtenus et caracterises. Parmi un ensemble de plantes [F.sub.1] obtenues, seuls cinq hybrides (H1-H5) se demarquaient sur le plan morphologique du parent femelle B. napus en affichant une faible fecondite et des caracteres de l'I. indigotica en plus de s'en distinguer pour ce qui est du nombre de chromosomes. H1-H4 affichaient un nombre semblable bien que variable de chromosomes chez leurs cellules somatiques et meiotiques (2n = 25-30), tandis que H5 possedait 2n = 19 chromosomes, soit le nombre present chez un individu haploide du B. napus. Une analyse GISH des cellules des hybrides H1 et H5 a detecte un chromosome entier de l'I. indigotica ainsi qu'un ou deux fragments chromosomiques terminaux. De nouveaux types du B. napus presentant des alterations phenotypiques et genomiques ont ete obtenus suite au croisement de H1 avec le B. napus original (comme parent male) suivi des plusieurs generations d'autofecondation ou encore suite a l'autofecondation de H5. Un descendant de l'hybride H1 a 2n = 20 a ete obtenu suite a deux cycles de croisement avec l'I. indigotica (comme parent male) et il presentait un phenotype rappelant un certain type du B. rapa, ce qui suggerait que l'hybride H1 aurait vraisemblablement conserve tous les chromosomes du genome A et perdu certains des chromosomes du genome C du B. napus parental. Les auteurs discutent des raisons pouvant expliquer la formation d'hybrides partiels ayant des jeux chromosomiques inattendus et l'elimination chromosomique. Mots-cles : Brassica napus, Isatis indigotica, hybride inter-tribus, hybridation genomique in situ (GISH), polymorphisme de longueur des fragments amplifies (AFLP), elimination chromosomique. [Traduit par la Redaction], Introduction Most aspects of chromosome behavior are considered to be under genetic control, as are most morphological characteristics (Rees 1961). For example, genetic control has been demonstrated for asynapsis (Beadle [...]

From dual-color genomic in situ hybridization (GISH) analysis of three trigenomic hybrids, Brassica maurorum (MM, 2n = 16) x B. juncea (AABB, 2n = 36) (M.AB), B. maurorum x B. carinata (BBCC, 2n = 34) (M.BC), and B. carinata x B. maurorum (BC.M), the three genomes of each hybrid were distinguished and autosyndesis and allosyndesis were evaluated. In M.AB, up to two autosyndetic bivalents occurred among the chromosomes of each genome; a maximum of three allosyndetic bivalents appeared between A-B, A-M, and B-M genomes. The similar pairings in M.BC and BC.M suggested that the cytoplasm of B. maurorum or B. carinata had no obvious effect on chromosome pairing. In M.BC and BC.M, a maximum of one autosyndetic bivalent was found for B and M genomes, but two were found for the C genome; from 0 to 2 allosyndetic bivalents were observed between B-C, B-M, and C-M genomes. The B-M allosyndesis frequency was higher than the A-M or C-M allosyndesis frequency in these hybrids, revealing the closer relationship of B and M genomes. The allosyndesis frequency was higher than the autosyndesis frequency among A, B, and C genomes in these combinations, suggesting that intergenomic homoeology was higher than intragenomic homoeology. The implications for genome evolution and crop breeding are discussed. Key words: Brassica, interspecific hybrid, chromosome pairing, dual-color genomic in situ hybridization, autosyndesis, allosyndesis. Les auteurs ont employe l'hybridation genomique in situ (GISH) bicolore pour analyser trois hybrides trigenomiques, soit le Brassica maurorum (MM, 2n = 16) x B. juncea (AABB, 2n = 36) (M.AB), le B. maurorum x B. carinata (BBCC, 2n = 34) (M.BC), et le B. carinata x B. maurorum (BC.M). Les trois genomes ont ete distingues chez chaque hybride et les auteurs ont evalue l'autosyndese et l'allosyndese. Chez l'hybride M.AB, jusqu'a deux bivalents autosyndetiques ont ete observes parmi les chromosomes de chaque genome et un maximum de trois bivalents allosyndetiques ont ete; observes entre les genomes A-B, A-M et B-M. Les appariements semblables chez les hybrides M.BC et BC.M suggerent que le cytoplasme du B. maurorum ou du B. carinata n'a eu aucun effet evident sur l'appariement chromosomique. Chez les hybrides M.BC et BC.M, au plus un bivalent autosyndetique a ete observe; pour les genomes B et M, mais deux pour le genome C. Entre 0 et 2 bivalents allosyndetiques ont ete observes entre les genomes B-C, B-M et C-M. La frequence d'allosyndese B-M etait superieure a la frequence d'allosyndeese A-M ou C-M chez ces hybrides, ce qui suggere une relation plus proche. La frequence superieure de l'allosyndese par rapport a l'autosyndese parmi les genomes A, B et C chez ces combinaisons suggere que l'homeologie intergenomique est plus grande que l'homeologie intragenomique. Les auteurs discutent des implications de ces observations en ce qui a trait a revolution des genomes et l'amelioration genetique. Mots-cles : Brassica, hybride interspecifique, appariement chromosomique, hybridation genomique in situ bicolore, autosyndese, allosyndese. [Traduit par la Redaction], Introduction Genome analysis and cytogenetic research of Brassica crops were pioneered by Morinaga (Prakash et al. 2009), who established that crop brassicas consist of six species. Of these, three are [...]