Fertility, genome stability, and homozygosity in a diverse set of resynthesized rapeseed lines

Katche, Elizabeth Ihien; Schierholt, Antje; Becker, Heiko C.; Batley, Jacqueline; Mason, Annaliese S.

doi:10.1016/j.cj.2022.07.022

Cited by 6 publications

(4 citation statements)

References 77 publications

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“…In support of our results, non-homologous translocations between the A and C genomes have previously been observed in B. napus using various methods, including microscopy (Osborn et al 2003;Sheidai et al 2003) segregation distortion of mapping populations (Schranz and Osborn 2000;Stein et al 2017) , and sequence read mapping depth (Chalhoub et al 2014;Samans et al 2017). Non-homologous pairing in polyploids has also been observed in several other polyploid species, although the frequency is rather low compared to synthetic polyploids (Madlung et al 2005;Henry et al 2014;Ihnien Katche et al 2022) and, even though different chromosomes might interact during the initial stages of meiosis, these configurations tend to resolve into correct homolog pairing (bivalent formation) as meiosis progresses (Comai et al 2003). How meiotic stabilization or diploid-like behavior has been achieved in natural polyploids is not yet fully understood, although many potential hypothesis have been described, involving for example new mutations, changes in genetic regulation, or inheritance of pre-adapted alleles (reviewed in (Gonzalo 2022)).…”

Section: Discussionsupporting

confidence: 90%

Karyotype instability varies by species and genotype combination in allohexaploidBrassica

Quezada-Martinez,

Batley,

Mason

2023

Preprint

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SyntheticBrassicaallohexaploids (2n = AABBCC) do not exist naturally but can be produced between six different parent species combinations, and can be used to investigate processes of polyploid formation and genome stabilization. In this study, we investigated hybridization potential, accumulation and frequency of copy number variants (CNVs), fertility, and karyotype stability in advanced generations of diverse allohexaploid genotypes belonging to differentBrassicaallohexaploid species combinations (NCJ types:B. napus×B. carinata×B. juncea; junleracea types:B. juncea×B. oleracea; naponigra types:B. napus×B. nigra; and carirapa types:B. rapa×B. carinata). Only 3.2% of allohexaploid plants investigated were euploids, with high frequencies of rearrangements. Significant differences between genotypes and between lineages within parent genotype combinations were found for frequencies of euploids and rearrangements, with one NCJ line showing relatively high karyotype stability. Hybridization between different allohexaploids was mostly achievable, with 0 - 4.6 seeds per flower bud on average, and with strong effects of maternal genotype. Novel hybrids between allohexaploid lineages showed similar fertility and stability to their parents. In the novel hybrid population, a significant correlation was observed between the inheritance of A-genome chromosome fragments (relative to C-genome fragments) and the total number of seeds produced per plant (r= 0.24). Our results suggest that syntheticBrassicaallohexaploids can develop genomic stability, but that this occurs at very low frequencies, and may not always be under selective pressure due to the unpredictable relationship between fertility and genome composition in these hybrid types.

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Section: Discussionsupporting

confidence: 90%

Karyotype instability varies by species and genotype combination in allohexaploidBrassica

Quezada-Martinez,

Batley,

Mason

2023

Preprint

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“…Resynthesized lines serve as valuable genetic resources in rapeseed breeding, contributing genetic diversity and crucial traits such as disease resistance (clubroot disease, sclerotinia stem rot, verticillium wilt, blackleg disease), yield, heterosis, insect resistance, pod shatter resistance, early flowering, and drought tolerance 42 . While some artificial rapeseeds were initially used solely as breeding materials due to low yields 36 , 43 , 44 , improved pollen and seed fertility have been achieved in advanced generations 41 , 45 , 46 . Consequently, selection lines from advanced generations with enhanced self-compatibility and seed fertility can be directly utilized for varietal development.…”

Section: Discussionmentioning

confidence: 99%

Resynthesizing Brassica napus with race specific resistance genes and race non-specific QTLs to multiple races of Plasmodiophora brassicae

Masud Karim,

2024

Sci Rep

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Clubroot disease in canola (Brassica napus) continues to spread across the Canadian prairies. Growing resistant cultivars is considered the most economical means of controlling the disease. However, sources of resistance to clubroot in B. napus are very limited. In this study, we conducted interspecific crosses using a B. rapa line (T19) carrying race-specific resistance genes and two B. oleracea lines, ECD11 and JL04, carrying race non-specific QTLs. Employing embryo rescue and conventional breeding methods, we successfully resynthesized a total of eight B. napus lines, with four derived from T19 × ECD11 and four from T19 × JL04. Additionally, four semi-resynthesized lines were developed through crosses with a canola line (DH16516). Testing for resistance to eight significant races of Plasmodiophora brassicae was conducted on seven resynthesized lines and four semi-resynthesized lines. All lines exhibited high resistance to the strains. Confirmation of the presence of clubroot resistance genes/QTLs was performed in the resynthesized lines using SNP markers linked to race-specific genes in T19 and race non-specific QTLs in ECD11. The developed B. napus germplasms containing clubroot resistance are highly valuable for the development of canola cultivars resistant to clubroot.

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“…To achieve this goal in inbred B. napus, it will be necessary to look to related species (Katche et al 2019). Brassica napus germplasm can be readily enriched by using resynthesis: genotypes of progenitor species B. rapa × B. oleracea can be utilized to directly produce 2n = AACC types, which are optimal for further breeding (Katche et al 2023). Direct crossing between B. rapa and B. napus can also be carried out, followed by selection for euploid (2n = AACC) progeny; likewise crosses between B. oleracea and B. napus, although these often require embryo rescue (reviewed by FitzJohn et al 2007).…”

Section: A Critical Discussion Of the Pyramiding Strategymentioning

confidence: 99%

Breeding and management of major resistance genes to stem canker/blackleg in Brassica crops

Vasquez-Teuber

Rouxel

Mason

et al. 2023

Preprint

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Blackleg (also known as Phoma or stem canker) is a major, worldwide disease of Brassica crop species (e.g. oilseed rape, rapeseed, canola) caused by the ascomycete fungus Leptosphaeria maculans. The outbreak and severity of this disease depend on environmental conditions and management practices such as the use of fungicides and crop rotations, tilling, as well as a complex interaction between the pathogen and its hosts. Genetic resistance is a major method to control the disease (and the only control method in some parts of the world, such as continental Europe), but efficient use of genetic resistance is faced with many difficulties: (i) the scarcity of germplasm/genetic resources available, (ii) the different history of use of resistance genes in different parts of the world and the different populations of the fungus the resistance genes are exposed to, (iii) the complexity of the interactions between the plant and the pathogen, that expand beyond typical gene-for-gene interactions, (iv) the incredible evolutionary potential of the pathogen and the importance of knowing the molecular processes set up by the fungus to “breakdown’ resistances, so that we may design high-throughput diagnostic tools for population surveys, and (v) the different strategies and options to build up the best resistances and to manage them so that they are durable. In this paper, we aim to provide a comprehensive overview of these different points, stressing the differences between the different continents and the current prospects to generate new and durable resistances to blackleg disease.

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Fertility, genome stability, and homozygosity in a diverse set of resynthesized rapeseed lines

Cited by 6 publications

References 77 publications

Karyotype instability varies by species and genotype combination in allohexaploidBrassica

Karyotype instability varies by species and genotype combination in allohexaploidBrassica

Resynthesizing Brassica napus with race specific resistance genes and race non-specific QTLs to multiple races of Plasmodiophora brassicae

Breeding and management of major resistance genes to stem canker/blackleg in Brassica crops

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