Extent and structure of linkage disequilibrium in canola quality winter rapeseed (Brassica napus L.)

Ecke, Wolfgang; Clemens, Rosemarie; Honsdorf, Nora; Becker, Heiko C.

doi:10.1007/s00122-009-1221-0

Cited by 70 publications

(82 citation statements)

References 38 publications

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“…Half of these displayed the same multilocus genotype as did Darmor-bzh or Yudal, while the other half was recombinant in the interval with alleles at the peak of the QTL being in agreement with the meiotic phenotype (see Supplemental Figure 3 online). These results confirm the most likely position for PrBn (between markers CB10013a and BnGMs185; Figure 3); owing to the rapid decay of linkage disequilibrium with distance in B. napus (Ecke et al, 2010), the statistical associations we found certainly reflects the close proximity of PrBn to the markers we used. These results also demonstrate that natural variation in meiotic behavior among B. napus allohaploids is consistent with the segregation of two alleles at the PrBn locus.…”

Section: Discussionsupporting

confidence: 82%

Repeated Polyploidy Drove Different Levels of Crossover Suppression between Homoeologous Chromosomes inBrassica napusAllohaploids

et al. 2010

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Allopolyploid species contain more than two sets of related chromosomes (homoeologs) that must be sorted during meiosis to ensure fertility. As polyploid species usually have multiple origins, one intriguing, yet largely underexplored, question is whether different mechanisms suppressing crossovers between homoeologs may coexist within the same polyphyletic species. We addressed this question using Brassica napus, a young polyphyletic allopolyploid species. We first analyzed the meiotic behavior of 363 allohaploids produced from 29 accessions, which represent a large part of B. napus genetic diversity. Two main clear-cut meiotic phenotypes were observed, encompassing a twofold difference in the number of univalents at metaphase I. We then sequenced two chloroplast intergenic regions to gain insight into the maternal origins of the same 29 accessions; only two plastid haplotypes were found, and these correlated with the dichotomy of meiotic phenotypes. Finally, we analyzed genetic diversity at the PrBn locus, which was shown to determine meiotic behavior in a segregating population of B. napus allohaploids. We observed that segregation of two alleles at PrBn could adequately explain a large part of the variation in meiotic behavior found among B. napus allohaploids. Overall, our results suggest that repeated polyploidy resulted in different levels of crossover suppression between homoeologs in B. napus allohaploids.

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Section: Discussionsupporting

confidence: 82%

Repeated Polyploidy Drove Different Levels of Crossover Suppression between Homoeologous Chromosomes inBrassica napusAllohaploids

et al. 2010

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“…The lower marker number on the BC 1 map is a consequence of the dominant inheritance of the AFLP markers used for marker analysis, which allowed only the mapping of markers with the 2) as the expected ratio *, **, *** diploidization rate is significantly different from the mean diploidization rate of 'Express 617' at P = 0.05 (v 2 = 3.84), P = 0.01 (v 2 = 6.64) and P = 0.001 (v 2 = 10.83), respectively, n.s. : not significant (P [ 0.05 or the diploidization rate is between the boundaries of the confidence interval of the mean of 'Express 617') in other maps, for example the map published by Ecke et al (2010), C4 (N14) was much larger. In addition, in the haploid MDE map and the BC 1 map-both maps developed in mapping populations derived from the same F 1 plant as the diploid MDE population-C4 was also only present as a small fragment or missing altogether.…”

Section: Discussionmentioning

confidence: 86%

“…AFLP analyses were carried out following the multiplexing protocol described by Ecke et al (2010). The same five primer sets (20 primer combinations) used in the development of the DH, haploid MDE and BC 1 maps and for the characterization of the ISLs were again used for the analysis of skewed segregations and for map construction in the diploid MDE population.…”

Section: Analysis Of Ploidy Levelmentioning

confidence: 99%

“…Using these markers, a genetic map of 470 markers could be constructed (Table S1), which consists of 19 linkage groups that could be assigned to the 19 chromosomes of rapeseed based on markers shared with the DH map and a map from the cross 'Express 617' 9 'R53' (Ecke et al 2010). Of linkage group C4 only as a short fragment of five markers was present.…”

Section: Genetic Mapping In the Diploid Mde Populationmentioning

confidence: 99%

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Identification and evaluation of intervarietal substitution lines of rapeseed (Brassica napus L.) with donor segments affecting the diploidization rate of isolated microspores

et al. 2016

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In Brassica species microspore derived doubled haploid lines are an important tool in breeding and research. A limiting step in the production of doubled haploid lines is the diploidization of the microspores. Strong differences have been observed in diploidization rates between different genotypes but little is know about the genetic control of these differences. To identify genomic regions that carry genetic factors controlling the diploidization rate of isolated microspores of rapeseed, marker segregations were compared between segregating populations of diploid and haploid microspore derived embryos and a BC 1 from a cross between 'Express 617' and 'RS239'. After map construction ten intervarietal substitution lines from the same cross were selected with donor segments covering five genomic regions that showed a pattern of skewed marker segregations across the three populations indicative of the segregation of genes controlling the diploidization rates. The diploidization rates of microspores of the ten lines ranged from 23.9 to 58.7 % while the recurrent parent 'Express 617' showed a rate of 52.5 %. For three lines the diploidization rates were significantly lower (P = 0.05) than the rate of 'Express 617'. By comparing donor segments between the significant and the non-significant lines, seven genomic regions that cover just between 4.17 and 6.16 % of the rapeseed genome were identified that may contain genetic factors controlling diploidization rates in rapeseed. In addition, one marker was found that has a high probability to be linked to such a factor. The significant lines represent an ideal material for further in depth studies of this trait.

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“…DNA was extracted from the frozen plantlets using the innuSPEED Plant DNA kit (Analytik Jena AG, Konrad-Zuse-Strasse 1, Jena, Germany) according to the manufacturer's instructions. AFLP analyses were carried out following the multiplexing protocol described by Ecke et al (2010). The same five primer sets (20 primer combinations) used in the development of the DH map, the maps of the two MDE and the BC 1 populations, as well as in the characterization of the ISLs were again used for AFLP analysis in the DEPC population.…”

Section: Donor Plant Growthmentioning

confidence: 99%

Identification and evaluation of intervarietal substitution lines of rapeseed (Brassica napus L.) with donor segments affecting the direct embryo to plant conversion rate of microspore-derived embryos

et al. 2016

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Microspore culture has become an important tool in many species, including Brassicas, for the production of entirely homozygous lines, so called double haploid (DH) lines. The primary products of microspore culture are embryo-like structures, called microspore-derived embryos (MDEs). A major problem in the development of DH lines is the often low efficiency of Direct Embryo to Plant Conversion (DEPC). During the development of DH populations, favourable alleles of genes affecting the DEPC rate will be under selection. This selection should lead to skewed segregations at markers linked to these genes. By comparing skewed marker segregations in four populations, a population of doubled haploid plantlets, a haploid and a doubled haploid MDE population, and a BC 1 population, 20 genomic regions were identified, which showed patterns of skewed segregations across the populations, indicative of the segregation of genetic factors controlling DEPC rates. Four regions and eight intervarietal substitution lines (ISLs) with donor segments overlapping these regions were selected for further studies. Three ISLs, ER654, ER661 and ER653 with DEPC rates of 49.1, 54.5 and 57.2 %, showed significantly reduced DEPC rates compared to the rate of the recurrent parent of 76.5 %. By comparing donor segments between the significant and the non-significant lines, eight genomic regions were identified that may contain genetic factors controlling the DEPC rate in rapeseed. These regions range in size from 0 (represented by just one marker) to 16.5 cM and cover together just 1.33 % of the genetic map used to characterize the donor segments in the ISLs.

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Extent and structure of linkage disequilibrium in canola quality winter rapeseed (Brassica napus L.)

Cited by 70 publications

References 38 publications

Repeated Polyploidy Drove Different Levels of Crossover Suppression between Homoeologous Chromosomes inBrassica napusAllohaploids

Repeated Polyploidy Drove Different Levels of Crossover Suppression between Homoeologous Chromosomes inBrassica napusAllohaploids

Identification and evaluation of intervarietal substitution lines of rapeseed (Brassica napus L.) with donor segments affecting the diploidization rate of isolated microspores

Identification and evaluation of intervarietal substitution lines of rapeseed (Brassica napus L.) with donor segments affecting the direct embryo to plant conversion rate of microspore-derived embryos

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