Fertile allohexaploid Brassica hybrids obtained from crosses between B. oleracea and B. juncea via ovule rescue and colchicine treatment of cuttings

Mwathi, Margaret W.; Gupta, Manik; Quezada-Martinez, Daniela; Pradhan, Aneeta; Batley, Jacqueline; Mason, Annaliese S.

doi:10.1007/s11240-019-01728-x

Cited by 12 publications

(12 citation statements)

References 38 publications

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“…Some resynthesized Brassica allohexaploids (AABBCC) are also highly fertile, but with some sterile plants within each generation (Mwathi et al 2017;Mwathi et al 2020;Gaebelein et al 2019b). Whether the fertility in octoploid B. napus in our study is related to sub-genomic interactions or to particular genetic combinations is unclear.…”

Section: Discussionmentioning

confidence: 77%

“…In resynthesized Brassica allohexaploids (AABBCC), meiotic stability and fertility vary based on parental species origin and genotype (reviewed by Gaebelein and Mason 2018). For instance, some allohexaploid genotypes from the cross B. carinata × B. rapa are immediately meiotically stable (Gupta et al 2016), while the majority are unstable (Tian et al 2010), while striking differences in fertility and stability have been observed between allohexaploids derived from the cross B. juncea × B. oleracea (Mwathi et al 2020;Zhou et al 2016), B. napus × B. nigra (Gaebelein et al 2019a) and (B. napus × B. carinata) × B. juncea (Gaebelein et al 2019b;Mwathi et al 2017). The meiotic stability of allohexaploid AABBCC may be affected by both interactions between the A, B and C sub-genomes, as well as specific genetic loci (Gaebelein et al 2019b;Zhou et al 2016).…”

Section: Discussionmentioning

confidence: 99%

“…Meanwhile, some hexaploid Brassica AAAACC plants also failed to set seed ( McNaughton 1973 ), similar to observations in autooctoploid Brassica ( Liu 2014 ). Some resynthesized Brassica allohexaploids (AABBCC) are also highly fertile, but with some sterile plants within each generation ( Mwathi et al 2017 ; Mwathi et al 2020 ; Gaebelein et al 2019b ). Whether the fertility in octoploid B. napus in our study is related to sub-genomic interactions or to particular genetic combinations is unclear.…”

Section: Discussionmentioning

confidence: 99%

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Genome-Wide Duplication of Allotetraploid Brassica napus Produces Novel Characteristics and Extensive Ploidy Variation in Self-Pollinated Progeny

Yin

Zhu

Luo

et al. 2020

G3 Genes|Genomes|Genetics

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Whole genome duplications (WGDs) have played a major role in angiosperm species evolution. Polyploid plants have undergone multiple cycles of ancient WGD events during their evolutionary history. However, little attention has been paid to the additional WGD of the existing allopolyploids. In this study, we explored the influences of additional WGD on the allopolyploid Brassica napus. Compared to tetraploid B. napus, octoploid B. napus (AAAACCCC, 2n = 8x =76) showed significant differences in phenotype, reproductive ability and the ploidy of self-pollinated progeny. Genome duplication also altered a key reproductive organ feature in B. napus, that is, increased the number of pollen apertures. Unlike autopolyploids produced from the diploid Brassica species, the octoploid B. napus produced from allotetraploid B. napus had a relatively stable meiotic process, high pollen viability and moderate fertility under self-pollination conditions, indicating that sub-genomic interactions may be important for the successful establishment of higher-order polyploids. Doubling the genome of B. napus provided us with an opportunity to gain insight into the flexibility of the Brassica genomes. The genome size of self-pollinated progeny of octoploid B. napus varied greatly, and was accompanied by extensive genomic instability, such as aneuploidy, mixed-ploidy and mitotic abnormality. The octoploid B. napus could go through any of genome reduction, equilibrium or expansion in the short-term, thus providing a novel karyotype library for the Brassica genus. Our results reveal the short-term evolutionary consequences of recurrent polyploidization events, and help to deepen our understanding of polyploid plant evolution.

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Genome-Wide Duplication of Allotetraploid Brassica napus Produces Novel Characteristics and Extensive Ploidy Variation in Self-Pollinated Progeny

Yin

Zhu

Luo

et al. 2020

G3 Genes|Genomes|Genetics

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“…The creation of artificial Brassica allohexaploid could potentially result in the development of new oilseed and vegetable crops types with greater inter-subgenomic heterosis. These synthetic tri-genomic hexaploid Brassica species are potentially more vigorous and adaptable to a wider range of environmental conditions (Yan et al, 2009 ; Pradhan et al, 2010 ; Tian et al, 2010 ; Geng et al, 2013 ; Malek et al, 2013 ; Li et al, 2015 ; Gupta et al, 2016 ; Zhou et al, 2016 ; Mwathi et al, 2020 ). SNP genotyping was carried out by Gaebelein et al ( 2019 ) using the 90K Brassica SNP array and GWAS to determine the relative impact of genome rearrangement events and inherited allelic variants on meiotic stability.…”

Section: Functional Trait Discovery and Characterizationmentioning

confidence: 99%

Genomics Armed With Diversity Leads the Way in Brassica Improvement in a Changing Global Environment

et al. 2021

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Meeting the needs of a growing world population in the face of imminent climate change is a challenge; breeding of vegetable and oilseed Brassica crops is part of the race in meeting these demands. Available genetic diversity constituting the foundation of breeding is essential in plant improvement. Elite varieties, land races, and crop wild species are important resources of useful variation and are available from existing genepools or genebanks. Conservation of diversity in genepools, genebanks, and even the wild is crucial in preventing the loss of variation for future breeding efforts. In addition, the identification of suitable parental lines and alleles is critical in ensuring the development of resilient Brassica crops. During the past two decades, an increasing number of high-quality nuclear and organellar Brassica genomes have been assembled. Whole-genome re-sequencing and the development of pan-genomes are overcoming the limitations of the single reference genome and provide the basis for further exploration. Genomic and complementary omic tools such as microarrays, transcriptomics, epigenetics, and reverse genetics facilitate the study of crop evolution, breeding histories, and the discovery of loci associated with highly sought-after agronomic traits. Furthermore, in genomic selection, predicted breeding values based on phenotype and genome-wide marker scores allow the preselection of promising genotypes, enhancing genetic gains and substantially quickening the breeding cycle. It is clear that genomics, armed with diversity, is set to lead the way in Brassica improvement; however, a multidisciplinary plant breeding approach that includes phenotype = genotype × environment × management interaction will ultimately ensure the selection of resilient Brassica varieties ready for climate change.

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“…The third subgenome taken from a close or wild relative could benefit oilseed crops by adding disease resistance (Chen et al, 2011) and heat tolerance genes (Kumari et al, 2018). However, the development of interspecific allohexaploids was attempted by earlier researchers by crossing of allotetraploids and diploid species followed by ovary culture, where they were treated with chromosomes doubling agents (Meng et al, 1998;Rahman, 2001;Pradhan et al, 2010;Gupta et al, 2016;Mwathi et al, 2017Mwathi et al, , 2020, but their stability was still dubious (Mwathi et al, 2019). Mason et al (2012) used unreduced gametes by crossing all three allotetraploids of U's triangle species, but they only obtained a single near-allohexaploid.…”

Section: Introductionmentioning

confidence: 99%

Development of a Yellow-Seeded Stable Allohexaploid Brassica Through Inter-Generic Somatic Hybridization With a High Degree of Fertility and Resistance to Sclerotinia sclerotiorum

et al. 2020

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The Brassica coenospeceis have treasure troves of genes that could be beneficial if introgressed into cultivated Brassicas to combat the current conditions of climate change. Introducing genetic variability through plant speciation with polyploidization is well documented, where ploidy augmentation of inter-generic allohexaploids using somatic hybridization has significantly contributed to genetic base broadening. Sinapis alba is a member of the Brassicaceae family that possesses valuable genes, including genes conferring resistance to Sclerotinia sclerotiorum, Alternaria brassicae, pod shattering, heat, and drought stress. This work aimed to synthesize stable allohexaploid (AABBSS) Brassica while incorporating the yellow-seed trait and resistance to S. sclerotiorum stem rot. The two fertile and stable allohexaploids were developed by polyethylene glycol mediated protoplast fusions between Brassica juncea (AABB) and S. alba (SS) and named as JS1 and JS2. These symmetric hybrids (2n = 60) were validated using morphological and molecular cytology techniques and were found to be stable over consecutive generations. The complete chromosome constitution of the three genomes was determined through genomic in situ hybridization of mitotic cells probed with S. alba genomic DNA labeled with fluorescein isothiocyanate. These two allohexaploids showed 24 hybridization signals demonstrating the presence of complete diploid chromosomes from S. alba and 36 chromosomes from B. juncea. The meiotic pollen mother cell showed 30 bivalent sets of all the 60 chromosomes and none of univalent or trivalent observed during meiosis. Moreover, the backcross progeny 1 plant revealed 12 hybridization signals out of a total of 48 chromosome counts. Proper pairing and separation were recorded at the meiotic metaphase and anaphase, which proved the stability of the allohexaploid and their backcross progeny. When screening, the allohexaploid (JS2) of B. juncea and S. alba displayed a high degree of resistance to S. sclerotiorum rot along with a half-yellow and half-brown (mosaic) seed coat color, while the B. juncea and S. alba allohexaplopid1 (JS1) displayed a yellow seed coat color with the same degree of resistance to Sclerotinia rot.

show abstract

Fertile allohexaploid Brassica hybrids obtained from crosses between B. oleracea and B. juncea via ovule rescue and colchicine treatment of cuttings

Cited by 12 publications

References 38 publications

Genome-Wide Duplication of Allotetraploid Brassica napus Produces Novel Characteristics and Extensive Ploidy Variation in Self-Pollinated Progeny

Genome-Wide Duplication of Allotetraploid Brassica napus Produces Novel Characteristics and Extensive Ploidy Variation in Self-Pollinated Progeny

Genomics Armed With Diversity Leads the Way in Brassica Improvement in a Changing Global Environment

Development of a Yellow-Seeded Stable Allohexaploid Brassica Through Inter-Generic Somatic Hybridization With a High Degree of Fertility and Resistance to Sclerotinia sclerotiorum

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