Comparative meiosis and cytogenomic analysis in euploid and aneuploid hybrids of Urochloa P. Beauv

Rocha, Mara Jane da; Chiavegatto, Raquel Bezerra; Damasceno, Ana Gabriela; Rocha, Laiane Corsini; Sobrinho, Fausto Souza; Techio, Vânia Helena

doi:10.1007/s10577-019-09616-y

Cited by 9 publications

(11 citation statements)

References 24 publications

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“…While in diploid and polyploid accessions of U. decumbens a small shift in peak position on histogram usually does not compromise reliability of ploidy estimates, attention should be paid to the analysis of U. brizantha showing odd ploidy levels, because relative differences in fluorescence values of the peak positions between neighboring cytotypes (2 x , 4 x , 5 x , 6 x ) is decreased; such a phenomenon is also observed in species with ploidy levels greater than 6x [ 44 ]. A more precise examination of U. humidicola is also required due to confirmed aneuploidy [ 28 , 29 ], odd ploidy levels [ 34 ], and unrecognized diploid ancestors [ 64 ].…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flow Cytometry-Based Determination of Ploidy from Dried Leaf Specimens in Genomically Complex Collections of the Tropical Forage Grass Urochloa s. l.

Tomaszewska

Pellny

Hernández

et al. 2021

Genes

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Urochloa (including Brachiaria, Megathyrus and some Panicum) tropical grasses are native to Africa and are now, after selection and breeding, planted worldwide, particularly in South America, as important forages with huge potential for further sustainable improvement and conservation of grasslands. We aimed to develop an optimized approach to determine ploidy of germplasm collection of this tropical forage grass group using dried leaf material, including approaches to collect, dry and preserve plant samples for flow cytometry analysis. Our methods enable robust identification of ploidy levels (coefficient of variation of G0/G1 peaks, CV, typically <5%). Ploidy of some 348 forage grass accessions (ploidy range from 2x to 9x), from international genetic resource collections, showing variation in basic chromosome numbers and reproduction modes (apomixis and sexual), were determined using our defined standard protocol. Two major Urochloa agamic complexes are used in the current breeding programs at CIAT and EMBRAPA: the ’brizantha’ and ’humidicola’ agamic complexes are variable, with multiple ploidy levels. Some U. brizantha accessions have odd level of ploidy (5x), and the relative differences in fluorescence values of the peak positions between adjacent cytotypes is reduced, thus more precise examination of this species is required. Ploidy measurement of U. humidicola revealed aneuploidy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flow Cytometry-Based Determination of Ploidy from Dried Leaf Specimens in Genomically Complex Collections of the Tropical Forage Grass Urochloa s. l.

Tomaszewska

Pellny

Hernández

et al. 2021

Genes

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“…5 ); and such a phenomenon is also observed in species with ploidy levels greater than 6 x (Doležel et al ., 2007). A more precise examination of U. humidicola is also required due to confirmed aneuploidy (see Figs 4F and 5 ; Moraes et al ., 2019; da Rocha et al ., 2019), odd ploidy levels (Boldrini et al ., 2009b), and unrecognized diploid ancestors (Boldrini et al ., 2009a).…”

Section: Discussionmentioning

confidence: 99%

“…For Urochloa , ploidy estimation across the whole germplasm collection (excluding one species, U. ruziziensis , known only as a diploid) is required due to the different pathways of reproduction showing sexual and apomictic accessions within same species (Roche et al ., 2001), natural triploid interspecific hybrids (Timbó et al ., 2014), different genome compositions both within and between species (Tomaszewska et al ., 2021), confirmed aneuploidy (Moraes et al ., 2019; da Rocha et al ., 2019; Tomaszewska et al ., 2021), and different basic chromosome numbers ( x =6, 7, 8 and 9; de Wet, 1986; Basappa et al ., 1987; Bernini and Marin-Morales, 2001; Risso-Pascotto et al ., 2006; Boldrini et al ., 2009b; Worthington et al ., 2019).…”

Section: Introductionmentioning

confidence: 99%

Flow cytometry-based determination of ploidy from dried leaf specimens in genomically complex collections of the tropical forage grass Urochloa s. l

Tomaszewska

Pellny

Hernández

et al. 2021

Preprint

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We aimed to develop an optimized approach to determine ploidy for dried leaf material in a germplasm collection of a tropical forage grass group, including approaches to collect, dry and preserve plant samples for flow cytometry analysis. Urochloa (including Brachiaria, Megathyrus and some Panicum) tropical grasses are native to Africa and are now, after selection and breeding, planted worldwide, particularly in South America, as important forages with huge potential for further sustainable improvement and conservation of grasslands. The methods enable robust identification of ploidy levels (coefficient of variation, CV, typically <5%). Ploidy of some 353 forage grass accessions (ploidy range from 2 to 9), from international genetic resource collections, showing variation in basic chromosome numbers and reproduction modes (apomixis and sexual), were determined using our defined standard protocol. Two major Urochloa agamic complexes used in the current breeding programs at CIAT and EMBRAPA: the ' brizantha' and 'humidicola' agamic complexes are variable, with multiple ploidy levels and DNA content. U. brizantha has odd level of ploidy (x=5), and the relative differences in nuclear DNA content between adjacent cytotypes is reduced, thus more precise examination of this species is required. Ploidy measurement of U. humidicola revealed some aneuploidy.

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“…Cytogenetic analyses, such as the evaluation of chromosomal behavior in all phases of meiosis and counting the number of chromosomes, have already been performed with accessions of U. brizantha ( Mendes-Bonato et al, 2002a ; Risso-Pascotto et al, 2003a ; Pagliarini et al, 2012 ), U. decumbens ( Risso-Pascotto et al, 2002 ; Mendes-Bonato et al, 2002b ; Junqueira-Filho et al, 2003 ; Ricci et al, 2010 , 2011 ), U. ruziziensis ( Risso-Pascotto et al, 2003b , 2005 ), and U. humidicola ( Boldrini et al, 2006 ; Adamowski et al, 2007 ; Boldrini et al, 2011a , b ), among other species. Cytogenetic analyses have also been performed with interspecific hybrids ( Risso-Pascotto et al, 2004a , b ; Mendes-Bonato et al, 2006 , 2007 ; Adamowski et al, 2008 ; Felismino et al, 2010 , 2012 ; Fuzinatto et al, 2012 , 2017 ; da Rocha et al, 2019 ; de Campos Moraes et al, 2019 ) as well as intraspecific hybrids of U. decumbens ( Souza, 2013 ). These cytogenetic studies are essential to selection of the best and most cytogenetically stable parents and hybrids in the direction of crosses ( Simeão et al, 2021 ).…”

Section: Germplasm Resourcesmentioning

confidence: 99%

An Overview of the Genetics and Genomics of the Urochloa Species Most Commonly Used in Pastures

et al. 2021

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Pastures based on perennial monocotyledonous plants are the principal source of nutrition for ruminant livestock in tropical and subtropical areas across the globe. The Urochloa genus comprises important species used in pastures, and these mainly include Urochloa brizantha, Urochloa decumbens, Urochloa humidicola, and Urochloa ruziziensis. Despite their economic relevance, there is an absence of genomic-level information for these species, and this lack is mainly due to genomic complexity, including polyploidy, high heterozygosity, and genomes with a high repeat content, which hinders advances in molecular approaches to genetic improvement. Next-generation sequencing techniques have enabled the recent release of reference genomes, genetic linkage maps, and transcriptome sequences, and this information helps improve our understanding of the genetic architecture and molecular mechanisms involved in relevant traits, such as the apomictic reproductive mode. However, more concerted research efforts are still needed to characterize germplasm resources and identify molecular markers and genes associated with target traits. In addition, the implementation of genomic selection and gene editing is needed to reduce the breeding time and expenditure. In this review, we highlight the importance and characteristics of the four main species of Urochloa used in pastures and discuss the current findings from genetic and genomic studies and research gaps that should be addressed in future research.

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Comparative meiosis and cytogenomic analysis in euploid and aneuploid hybrids of Urochloa P. Beauv

Cited by 9 publications

References 24 publications

Flow Cytometry-Based Determination of Ploidy from Dried Leaf Specimens in Genomically Complex Collections of the Tropical Forage Grass Urochloa s. l.

Flow Cytometry-Based Determination of Ploidy from Dried Leaf Specimens in Genomically Complex Collections of the Tropical Forage Grass Urochloa s. l.

Flow cytometry-based determination of ploidy from dried leaf specimens in genomically complex collections of the tropical forage grass Urochloa s. l

An Overview of the Genetics and Genomics of the Urochloa Species Most Commonly Used in Pastures

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