Microsporogenesis in Brachiaria bovonei (Chiov.) Robyns and B. subulifolia (Mez) Clayton (Poaceae)

Risso-Pascotto, Claudicéia; Pagliarini, Maria Suely; Valle, Cacilda Borges do

doi:10.1590/s0103-90162009000500015

Cited by 11 publications

(3 citation statements)

References 15 publications

(11 reference statements)

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“…Micronuclei were also eliminated as microcytes (Figure 1j, k, l). The same type of behavior was reported in polyploid accessions of B. brizantha (Mendes-Bonato et al, 2002;RissoPascotto et al, 2003), B. nigropedata (Utsunomiya et al, 2005), B. jubata , B. dictyoneura (Risso-Pascotto et al, 2006a), B. dura (Risso-Pascotto et al, 2009a), and B. bovonei and B. subulifolia (Risso-Pascotto et al, 2009b). Irregular chromosome segregation compromises pollen fertility by producing unbalanced microspores.…”

Section: Resultssupporting

confidence: 56%

Microsporogenesis in Brachiaria brizantha (Poaceae) as a selection tool for breeding

Pagliarini¹,

Valle²,

Santos³

et al. 2012

Genet. Mol. Res.

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ABSTRACT. The genus Brachiaria comprises more than 100 species and is the single most important genus of forage grass in the tropics. Brachiaria brizantha, widely used in Brazilian pastures for beef and dairy production, is native to tropical Africa. As a subsidy to the breeding program underway in Brazil, cytological studies were employed to determine the chromosome number and to evaluate microsporogenesis in 46 accessions of this species available at Embrapa Beef Cattle (Brazil). Thirty-four accessions presented 2n = 36; seven had 2n = 45, and five had 2n = 54 chromosomes. Based on the higher level of chromosome association observed in diakinesis, in tetra-, penta-, and hexavalents, respectively, it was concluded that they are derived from x = 9; consequently, these accessions are tetra-(2n = 4x = 36), penta-(2n = 5x = 45), and hexaploids (2n = 6x = 54). The most common meiotic abnormalities were irregular chromosome segregation due to polyploidy. Chromosome stickiness, abnormal cytokinesis, noncongressed bivalents in metaphase I and chromosomes in metaphase II, and chromosome elimination were recorded at varying frequencies in several accessions. The mean percentage of meiotic abnormalities ranged from 0.36 to 95.76%. All the abnormalities had the potential to affect pollen viability by generating unbalanced gametes. Among the accessions, only the tetraploid ones with less than 40% of abnormalities are suitable as pollen donors in intra-and interspecific crosses. Currently, accessions with a high level of ploidy (5 and 6n) cannot be used as male genitors in crosses because of the lack of sexual female genitors with the same levels of ploidy.

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Section: Resultssupporting

confidence: 56%

Microsporogenesis in Brachiaria brizantha (Poaceae) as a selection tool for breeding

Pagliarini¹,

Valle²,

Santos³

et al. 2012

Genet. Mol. Res.

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“…Gaulden (1987) postulated that chromosome stickiness results from the defective behavior of one or two types of specific non-histone proteins involved in chromosome organization. Chromosome stickiness has been observed in several Brachiaria accessions and hybrids (Utsunomyia et al, 2005;Mendes-Bonato et al, 2001bRisso-Pascotto et al, 2009b;Felismino et al, 2010;Ricci et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Meiotic behavior and chromosome number of Urochloa adspersa (Trin.) R. D. Webster from the Brazilian Chaco

Felismino¹,

Maior²,

Damasceno³

et al. 2015

Genet. Mol. Res.

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ABSTRACT. This is the first report of meiotic division in Urochloa adspersa (Trin.) collected from the Brazilian Chaco. Meiotic analyses were performed on three specimens of U. adspersa named G10, G15, and G16. Inflorescences were collected and fixed in a mixture of ethanol and acetic acid (3:1, v/v) for 24 h and then stored in 70% alcohol. Diakinesis revealed different chromosome numbers and ploidy levels. All three plants were polyploids: G10 and G15 exhibited 2n = 6x = 54 chromosomes (arranged in 27 bivalents), while G16 exhibited 2n = 4x = 36 chromosomes (18 bivalents). Meiotic behavior was mainly normal in the hexaploid G15 and the tetraploid G16 (5.3 and 6.2% of the cells were abnormal, respectively), revealing only a few meiotic abnormalities that are common to polyploids, i.e., those related to irregular chromosome segregation. G10 exhibited other meiotic abnormalities during meiosis II, such as chromosome stickiness, irregular spindle orientation, and irregular cytokinesis, which led to the formation of a few triads, resulting in 16.9% of the cells being abnormal. The origin of these abnormalities is discussed, and we suggest that the genes that control meiotic steps may be present in the Urochloa gene pool.

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“…Beadle (1932) reported chromosome stickiness in maize for the first time and attributed the irregularity to a recessive mutant gene called sticky (st). It has been reported in different Brachiaria species (Mendes-Bonato et al, 2007;Pagliarini et al, 2008;Risso-Pascotto et al, 2009) with suggestions that chromosome stickiness may be under genetic control: controlled by a single pair of genes, two pairs of genes, or by the interaction of several genes which may be recessive or dominant. Stickiness might also be caused by environmental factors such as X-rays, temperature and soil elements (Mendes-Bonato et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Cytogenetic Diversity of Elsholtzia Ciliata Benth. (Lamiaceae) From Kashmir Himalaya

Malik¹,

Gupta²,

Kumari³

2012

Acta Biologica Cracoviensia Series Botanica

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Our cytomorphological study of various populations of Elsholtzia ciliata (Lamiaceae) collected from high-altitude sites of Kashmir Himalaya revealed two euploid cytomorphotypes, diploid (n=8) and tetraploid (n=16), growing sympatrically but inhabiting two different habitats. This is the first report of tetraploid (4×) E. ciliata from the Indian subcontinent. We found the course of meiois to be normal in diploids, but tetraploid individuals showed chromosome and meiotic irregularities: cytomixis at early prophase I, stickiness at metaphase I, and chromosome bridges at anaphase I. In tetraploids, 23 of the 26 pollen mother cells observed at metaphase I showed 0-6 quadrivalents, suggesting that the tetraploid is a segmental allopolyploid. Microsporogenesis was also abnormal in tetraploids, showing the formation of triads. All these anomalies are conducive to lower reproductive potential (40.70%) in tetraploids than in diploids (90.50%). Significant morphological differences between the two cytotypes are presented.K Ke ey y w wo or rd ds s:

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Microsporogenesis in Brachiaria bovonei (Chiov.) Robyns and B. subulifolia (Mez) Clayton (Poaceae)

Cited by 11 publications

References 15 publications

Microsporogenesis in Brachiaria brizantha (Poaceae) as a selection tool for breeding

Microsporogenesis in Brachiaria brizantha (Poaceae) as a selection tool for breeding

Meiotic behavior and chromosome number of Urochloa adspersa (Trin.) R. D. Webster from the Brazilian Chaco

Cytogenetic Diversity of Elsholtzia Ciliata Benth. (Lamiaceae) From Kashmir Himalaya

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