Desynapsis and precocious cytokinesis in Brachiaria humidicola (Poaceae) compromise meiotic division

Calisto, Vergílio; Fuzinatto, Veridiana Aparecida; Message, Hugo José; Mendes-Bonato, Andréa Beatriz; Boldrini, Kellen Regina; Pagliarini, Maria Suely; Valle, Cacilda Borges do

doi:10.1007/s12041-008-0004-8

Cited by 13 publications

(10 citation statements)

References 31 publications

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“…This abnormality was reported in one accession of B. humidicola (Calisto et al, 2008) and was correlated with abnormal cytokinesis. In P05, the expres-Sci.…”

Section: Resultssupporting

confidence: 54%

“…Several putative meiotic mutations have been reported among Brachiaria accessions (Mendes-Bonato et al, 2002bRisso-Pascotto et al, 2003, 2005bMendes-Vieira et al, 2005;Boldrini et al 2006;Gallo et al, 2007;Adamowski et al, 2007;Calisto et al, 2008) and in hybrids (Mendes-Bonato et al, 2004, 2006bRisso-Pascotto et al, 2005a;Fuzinatto et al, 2007ab;Adamowski et al, 2008;Felismino et al, 2008Felismino et al, , 2010. These putative mutations are frequently be-Sci.…”

Section: Resultsmentioning

confidence: 99%

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Meiotic behavior in apomictic Brachiaria ruziziensis × B. brizantha (Poaceae) progenies

Fuzinatto

Pagliarini

Valle

2012

Sci. agric. (Piracicaba, Braz.)

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Hybrids combining desirable traits from divergent parents are the main objective of some Brachiaria (Syn. Urochloa P. Beauv.) breeding programs. There is great interest in the development of apomictic hybrid cultivars that combine desirable genes such as resistance to spittlebugs, high nutritive value, and tolerance to acid soils. Microsporogenesis of six apomictic progenies resulting from a tetraploid (2n = 4x = 36) cross between B. ruziziensis × B. brizantha was evaluated under light microscopy. Genetic recombination, ensured by multivalent chromosome association and crossing-over at prophase occurred in low frequency among progenies, and in one, recombination was almost nonexistent. The percentage of meiocytes with meiotic abnormalities among progenies ranged from 16.6 % to 85.6 %. Besides an observed irregular chromosome segregation typical of polyploid hybrids in these five progenies, putative meiotic mutations characterized as desynapsis and divergent spindle organization occurred in three progenies. These anomalies caused frequent fractionation of the genome into several microspores of different sizes. In Brachiaria, new cultivars must be apomictic to fix the genotype. However, Brachiaria is a pseudogamous apomict, and viable gametes are necessary to produce viable seeds. Considering meiotic behavior, only two progenies are promising for advancement in the breeding program.

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“…This abnormality was reported in one accession of B. humidicola (Calisto et al, 2008) and was correlated with abnormal cytokinesis. In P05, the expres-Sci.…”

Section: Resultssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Meiotic behavior in apomictic Brachiaria ruziziensis × B. brizantha (Poaceae) progenies

Fuzinatto

Pagliarini

Valle

2012

Sci. agric. (Piracicaba, Braz.)

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“…However, when some of these mutations occur, the resulting rate of univalents is very high, which has an impact on most of the bivalents (Calisto et al, 2008;Pagliarini et al, 2011), which was not observed in this study. Additionally, no asynaptic or desynaptic mutants have previously been described in triticale.…”

Section: Meiotic Behaviorcontrasting

confidence: 61%

Backcrossing to increase meiotic stability in triticale

et al. 2015

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ABSTRACT. Triticale (X Triticosecale Wittmack) is an intergeneric hybrid derived from a cross between wheat and rye. As a newly created allopolyploid, the plant shows instabilities during the meiotic process, which may result in the loss of fertility. This genomic instability has hindered the success of triticale-breeding programs. Therefore, strategies should be developed to obtain stable triticale lines for use in breeding. In some species, backcrossing has been effective in increasing the meiotic stability of lineages. To assess whether backcrossing has the same effect in triticale, indices of meiotic abnormalities, meiotic index, and pollen viability were determined in genotypes from multiple generations of triticale (P 1 , P 2 , F 1 , F 2 , BC 1a , and BC 1b ). All analyzed genotypes exhibited instability during (2015) meiosis, and their meiotic index values were all lower than normal. However, the backcrosses BC 1a and BC 1b showed the lowest mean meiotic abnormalities and the highest meiotic indices, demonstrating higher stability. All genotypes showed a high rate of pollen viability, with the backcrosses BC 1a and BC 1b again exhibiting the best values. Statistical analyses confirmed that backcrossing positively affects the meiotic stability of triticale. Our results show that backcrossing should be considered by breeders aiming to obtain triticale lines with improved genomic stability.

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“…Polyploidy is predominant in the genus Brachiaria and is correlated to apomixis (Valle and Savidan, 1996;Valle and Pagliarini, 2009) and the role of unreduced (male and female) gametes in the phenomenon is unquestionable. The formation of unreduced male gametes, originated by different mechanisms of abnormal cytokinesis, has been reported in B. brizantha (Risso-Pascotto et al, 2003), B. nigropedata (Utsunomiya et al, 2005), B. jubata (Mendes-Bonato et al, 2006a), and B. humidicola Gallo et al, 2007;Calisto et al, 2008). In the accessions under analysis, one progenitor, probably apomictic contributed with an unreduced gamete (2n = 36) and the maternal contribution derived from a sexual diploid plant, with a reduced gamete (N = 9).…”

Section: Resultsmentioning

confidence: 89%

Genome elimination during microsporogenesis in two pentaploid accessions of Brachiaria decumbens (Poaceae)

Ricci¹,

Pagliarini²,

Valle³

2010

Genet. Mol. Res.

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ABSTRACT. Polyploidy is a prominent and significant force in plant evolution, taking place since ancient times and continuing until today. Recent cytogenetic studies in the genus Brachiaria using germplasm collected from wild African savannas in the 1980s revealed that most species and accessions within species are polyploid. Diploid, tetraploid, and pentaploid accessions have been found. We found asynchronous meiosis during microsporogenesis, followed by genome elimination, in two pentaploid (2n = 5x = 45) accessions (D53 and D71) of a hardy, invasive pasture grass, introduced from Africa to Brazil, Brachiaria decumbens. In these accessions, chromosomes paired as 18 bivalents and nine univalents during diakinesis, suggesting that these accessions resulted from a recent event of natural hybridization. The lack of chromosome associations in the genomes suggests that these accessions resulted from hybridization between two genotypes that are not closely related, with low genome affinity and with different meiotic rhythms. This supposition is reinforced by the meiotic behavior of the nine univalents, which were always laggard in relation to the other chromosomes and eliminated as micronuclei Genome elimination in Brachiaria decumbens in microspores. The behavior of these accessions, which have an odd level of ploidy and confirmed genome elimination, supports the general assumption that a polyploid accession can undergo a new event of polyploidization by natural hybridization (neopolyploidyzation). This evidence for natural hybridization in Brachiaria shows that this is a wild genus in an ongoing evolutionary process.

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Desynapsis and precocious cytokinesis in Brachiaria humidicola (Poaceae) compromise meiotic division

Cited by 13 publications

References 31 publications

Meiotic behavior in apomictic Brachiaria ruziziensis × B. brizantha (Poaceae) progenies

Meiotic behavior in apomictic Brachiaria ruziziensis × B. brizantha (Poaceae) progenies

Backcrossing to increase meiotic stability in triticale

Genome elimination during microsporogenesis in two pentaploid accessions of Brachiaria decumbens (Poaceae)

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