A Modified Meiotic Recombination in Brassica napus Largely Improves Its Breeding Efficiency

Meiotic recombination is the main tool used by breeders to generate biodiversity, allowing genetic reshuffling at each generation. It enables the accumulation of favorable alleles while purging deleterious mutations. However, this mechanism is highly regulated with the formation of one to rarely more than three crossovers, which are not randomly distributed. In this study, we showed that it is possible to modify these controls in oilseed rape (Brassica napus, AACC, 2n = 4x = 38) and that it is linked to AAC allotriploidy and not to polyploidy per se. To that purpose, we compared the frequency and the distribution of crossovers along A chromosomes from hybrids carrying exactly the same A nucleotide sequence, but presenting three different ploidy levels: AA, AAC and AACC. Genetic maps established with 202 SNPs anchored on reference genomes revealed that the crossover rate is 3.6-fold higher in the AAC allotriploid hybrids compared to AA and AACC hybrids. Using a higher SNP density, we demonstrated that smaller and numerous introgressions of B. rapa were present in AAC hybrids compared to AACC allotetraploid hybrids, with 7.6 Mb vs. 16.9 Mb on average and 21 B. rapa regions per plant vs. nine regions, respectively. Therefore, this boost of recombination is highly efficient to reduce the size of QTL carried in cold regions of the oilseed rape genome, as exemplified here for a QTL conferring blackleg resistance.

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Homoeologous loci control the accumulation of seed glucosinolates in oilseed rape (Brassica napus)

Genome ◽

10.1139/g03-028 ◽

2003 ◽

Vol 46 (3) ◽

pp. 454-460 ◽

Cited By ~ 66

Author(s):

P M Howell ◽

A G Sharpe ◽

D J Lydiate

Keyword(s):

Brassica Napus ◽

Oilseed Rape ◽

Phenotypic Variation ◽

Comparative Mapping ◽

Genetic Maps ◽

Glucosinolate Content ◽

Marker Assisted Breeding ◽

Brassica Napus L ◽

Backcross Populations ◽

Seed Glucosinolates

The genetic control of seed glucosinolate content in oilseed rape was investigated using two intervarietal backcross populations. Four QTLs segregating in the population derived from a Brassica napus L.'Victor' × Brassica napus L.'Tapidor' cross, together accounting for 76% of the phenotypic variation, were mapped. Three of these loci also appeared to control the accumulation of seed glucosinolates in a Brassica napus L. 'Bienvenu' × 'Tapidor' cross, and accounted for 86% of the phenotypic variation. The three QTLs common to both populations mapped to homoeologous regions of the B. napus genome, suggesting that seed glucosinolate accumulation is controlled by duplicate genes. It was possible to extend the comparative analysis of QTLs controlling seed glucosinolate accumulation by aligning the published genetic maps generated by several research groups. This comparative mapping demonstrated that high-glucosinolate varieties often carry low-glucosinolate alleles at one or more of the loci controlling seed glucosinolate accumulation.Key words: backcross, comparative mapping, genetic linkage map, marker-assisted breeding, QTL.

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Indistinguishable patterns of recombination resulting from male and female meioses in Brassica napus (oilseed rape)

Genome ◽

10.1139/g97-007 ◽

1997 ◽

Vol 40 (1) ◽

pp. 49-56 ◽

Cited By ~ 13

Author(s):

A. L. Kelly ◽

A. G. Sharpe ◽

J. H. Nixon ◽

D. J. Lydiate ◽

E. J. Evans

Keyword(s):

Brassica Napus ◽

Oilseed Rape ◽

Genetic Maps ◽

Linkage Groups ◽

Male Population ◽

Female Population ◽

Male And Female ◽

Male Gametes ◽

Genome Map ◽

Backcross Populations

An F1 individual derived from a cross between two distinct lines of spring oilseed rape (Brassica napus) was used to produce a pair of complementary backcross populations, each consisting of 90 individuals. The F1 donated male gametes to the Male population and female gametes to the Female population. Genetic maps were generated from both populations and aligned using 117 common loci to form an integrated genome map of B. napus with 243 RFLP-defined loci. A comparison of the frequency and distribution of crossovers in the two populations of F1 gametes (assayed in the Male and Female populations) detected no differences. The genetic maps derived from the Male and Female populations each consisted of 19 linkage groups spanning 1544 and 1577 cM, respectively. The maps were aligned with other B. napus maps, and all 19 equivalent linkage groups were unambiguously assigned. The genetic size and general organisation of the new maps were comparable with those of pre-existing B. napus maps in most respects, except that the levels of polymorphism in the constituent A and C genomes were unusually similar in the new cross.Key words: genetic linkage map, sex differences, recombination frequency, segregation distortion.

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Conserved patterns of chromosome pairing and recombination in Brassica napus crosses

Genome ◽

10.1139/g97-066 ◽

1997 ◽

Vol 40 (4) ◽

pp. 496-504 ◽

Cited By ~ 35

Author(s):

I. A. P. Parkin ◽

D. J. Lydiate

Keyword(s):

Brassica Napus ◽

Oilseed Rape ◽

Chromosome Pairing ◽

Recombination Frequency ◽

Microspore Culture ◽

Genetic Maps ◽

Winter Oilseed Rape ◽

Homologous Chromosomes ◽

Novel Alleles ◽

Two Populations

The patterns of chromosome pairing and recombination in two contrasting Brassica napus F1 hybrids were deduced. One hybrid was from a winter oilseed rape (WOSR) × spring oilseed rape cross, the other from a resynthesized B. napus × WOSR cross. Segregation at 211 equivalent loci assayed in the population derived from each hybrid produced two collinear genetic maps. Alignment of the maps indicated that B. napus chromosomes behaved reproducibly as 19 homologous pairs and that the 19 distinct chromosomes of B. napus each recombined with unique chromosomes from the interspecific hybrid between Brassica rapa and Brassica oleracea. This result indicated that the genomes of the diploid progenitors of amphidiploid B. napus have remained essentially unaltered since the formation of the species and that the progenitor genomes were similar to those of modern-day B. rapa and B. oleracea. The frequency and distribution of crossovers were almost indistinguishable in the two populations, suggesting that the recombination machinery of B. napus could cope easily with different degrees of genetic divergence between homologous chromosomes. Efficient recombination in wide crosses will facilitate the introgression of novel alleles into oilseed rape from B. rapa and B. oleracea (via resynthesized B. napus) and reduce linkage drag.Key words: integrating genetic maps, microspore culture, segregation distortion, recombination frequency, locus distribution.

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Identification and characterization of microRNAs in oilseed rape (Brassica napus) responsive to infection with the pathogenic fungusVerticillium longisporumusingBrassicaAA (Brassica rapa) and CC (Brassica oleracea) as reference genomes

New Phytologist ◽

10.1111/nph.12934 ◽

2014 ◽

Vol 204 (3) ◽

pp. 577-594 ◽

Cited By ~ 49

Author(s):

Dan Shen ◽

Ina Suhrkamp ◽

Yu Wang ◽

Shenyi Liu ◽

Jan Menkhaus ◽

...

Keyword(s):

Brassica Napus ◽

Brassica Oleracea ◽

Brassica Rapa ◽

Oilseed Rape ◽

Identification And Characterization ◽

Reference Genomes

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Seed Yield and Sulphur Partitioning in Two Inbred Lines of Low and High Glucosinolate Oilseed Rape (Brassica napus L.) and Their Hybrids at Three Levels of Sulphur Supply

Acta Agriculturae Scandinavica Section B - Soil & Plant Science ◽

10.1080/09064719908565565 ◽

1999 ◽

Vol 49 (3) ◽

pp. 184-188

Author(s):

J. Davik ◽

A. K. Bakken

Keyword(s):

Brassica Napus ◽

Oilseed Rape ◽

Seed Yield ◽

Inbred Lines ◽

Brassica Napus L

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Genome Mining and Evaluation of the Biocontrol Potential of Pseudomonas fluorescens BRZ63, a New Endophyte of Oilseed Rape (Brassica napus L.) against Fungal Pathogens

International Journal of Molecular Sciences ◽

10.3390/ijms21228740 ◽

2020 ◽

Vol 21 (22) ◽

pp. 8740

Author(s):

Daria Chlebek ◽

Artur Pinski ◽

Joanna Żur ◽

Justyna Michalska ◽

Katarzyna Hupert-Kocurek

Keyword(s):

Brassica Napus ◽

Plant Growth ◽

Pseudomonas Fluorescens ◽

Oilseed Rape ◽

Plant Growth Promotion ◽

Fungal Pathogens ◽

Growth Promotion ◽

Genome Mining ◽

Plant Colonization ◽

Brassica Napus L

Endophytic bacteria hold tremendous potential for use as biocontrol agents. Our study aimed to investigate the biocontrol activity of Pseudomonas fluorescens BRZ63, a new endophyte of oilseed rape (Brassica napus L.) against Rhizoctonia solani W70, Colletotrichum dematium K, Sclerotinia sclerotiorum K2291, and Fusarium avenaceum. In addition, features crucial for biocontrol, plant growth promotion, and colonization were assessed and linked with the genome sequences. The in vitro tests showed that BRZ63 significantly inhibited the mycelium growth of all tested pathogens and stimulated germination and growth of oilseed rape seedlings treated with fungal pathogens. The BRZ63 strain can benefit plants by producing biosurfactants, siderophores, indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and ammonia as well as phosphate solubilization. The abilities of exopolysaccharide production, autoaggregation, and biofilm formation additionally underline its potential to plant colonization and hence biocontrol. The effective colonization properties of the BRZ63 strain were confirmed by microscopy observations of EGFP-expressing cells colonizing the root surface and epidermal cells of Arabidopsis thaliana Col-0. Genome mining identified many genes related to the biocontrol process, such as transporters, siderophores, and other secondary metabolites. All analyses revealed that the BRZ63 strain is an excellent endophytic candidate for biocontrol of various plant pathogens and plant growth promotion.

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