Introgression of B-genome chromosomes in a doubled haploid population ofBrassica napus ×B. carinata

Abstract

The Brassica B-genome species possess many valuable agronomic and disease resistance traits. To transfer traits from the B genome of B. carinata into B. napus, an interspecific cross between B. napus and B. carinata was performed and a doubled haploid (DH) population was generated from the BC2S3 generation. Successful production of interspecific DH lines as identified using B-genome microsatellite markers is reported. Five percent of DH lines carry either intact B-genome chromosomes or chromosomes that have deletions. All of the DH lines have linkage group J13/B7 in common. This was further confirmed using B. nigra genomic DNA in a fluorescent in situ hybridization assay where the B-genome chromosomes were visualized and distinguished from the A- and C-genome chromosomes. The 60 DH lines were also evaluated for morphological traits in the field for two seasons and were tested for resistance to blackleg, caused by Leptosphaeria maculans, under greenhouse conditions. Variation in the DH population followed a normal distribution for several agronomic traits and response to blackleg. The lines with B-genome chromosomes were significantly different (p < 0.01) from the lines without B-genome chromosomes for both morphological and seed quality traits such as days to flowering, days to maturity, and erucic acid content.

Analysis of B-Genome Chromosome Introgression in Interspecific Hybrids of Brassica napus × B. carinata

“…From these, a subset of markers that identified polymorphic loci in the Brassica C and B genomes was used to characterize KCN-10 and the different backcross generations. Amplification and resolution of microsatellite alleles by PCR and capillary electrophoresis were performed as described in Navabi et al (2010).…”

“…B3, B5, B6, and B8 were selected due to the presence of these four B-genome chromosomes in the parental BC 3 plants in the six BC 3 S 1 families. The molecular marker analysis was conducted as described in Navabi et al (2010).…”

“…Slides were prepared following tissue maceration with pectolyase and cellulase (Kato et al 2004;Lamb and Birchler 2006). B. nigra and B. oleracea genomic DNA and repeated sequences were labeled fluorescently (Navabi et al 2010). A 45S DNA clone was also used as a probe to detect nuclear organizing regions (NORs).…”

“…A 45S DNA clone was also used as a probe to detect nuclear organizing regions (NORs). Fluorescent in situ hybridization was performed following the method of Kato et al (2004) with slight modifications, as described in Navabi et al (2010).…”

“…However, a combination of these two approaches allows both linkage group differentiation and chromosomal copy number to be determined. It is not possible to identify specific Bgenome linkage groups using GISH with B. nigra genomic DNA, since the probe paints the centromeric area of any B-genome chromosome (Navabi et al 2010). To distinguish and visualize different B-genome chromosomes, one needs to use probes of BAC clones specific for a particular B-genome chromosome (Hasterok et al 2005;Howell et al 2008;Xiong et al 2010).…”