Chromosome number and microsporogenesis of two accessions of Brachiaria dura Stapf (Poaceae)

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

doi:10.1590/s1676-06032009000200024

Cited by 10 publications

(4 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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.

View full text Add to dashboard Cite

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.

show abstract

Section: Resultssupporting

confidence: 56%

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

Pagliarini¹,

Valle²,

Santos³

et al. 2012

Genet. Mol. Res.

View full text Add to dashboard Cite

show abstract

“…The genus Saccharum is well-known for its exclusively higher-order polyploid species, such as S. officinarum, S. robustum and S. spontaneum, the latter two with variable chromosome numbers or cytotypes. In this study, we confirmed that S. officinarum exhibits a relatively low number of meiotic abnormalities (~6%), i.e., regular meiosis, similar to that of other polyploids in the grass family (Leofanti et al 2017;Aissat et al 2019;Risso-Pascotto et al 2003). In contrast to our findings, these studies report abnormalities higher than 30%.…”

Section: Discussionsupporting

confidence: 81%

Meiotic abnormalities in sugarcane (Saccharum spp.): Evidence for peri- and paracentric inversions

Oliveira

Soares

Costa

et al. 2022

Preprint

View full text Add to dashboard Cite

The modern cultivars of sugarcane (Saccharum spp.) are highly polyploid and accumulate aneuploidies due to their history of domestication, genetic improvement and interspecific hybrid origin involving the domesticated sweet species S. officinarum ('noble cane') and the wild S. spontaneum, both with an evolutionary history of polyploidy. The first hybrids were backcrossed with S. officinarum, and selection from progenies in subsequent generations established the genetic basis of modern cultivars. Saccharum genome complexity has inspired several molecular studies that have elucidated aspects of sugarcane genome constitution, architecture and cytogenetics. Herein, we conducted a comparative analysis of the meiotic behavior of representatives of the parentals S. officinarum and S. spontaneum, and the commercial variety, SP80-3280. S. officinarum, an octoploid species, exhibited regular meiotic behavior. In contrast, S. spontaneum and SP80-3280 exhibited several abnormalities from metaphase I to the end of division. We reported and typified, for the first time, the occurrence of peri- and paracentric inversions. Using in-situ hybridization techniques, we were able to determine how pairing association occurred at diakinesis and, in particular, the chromosome composition of SP80-3280. Our findings have implications for sugarcane genetic mapping, genomics, and for studies on resynthesized polyploids.

show abstract

“…Brachiaria mutica and Brachiaria arrecta are tetraploidal species; the first exhibits irregular chromosome pairing and reproduction by apomixis, and the latter exhibits fairly regular bivalent pairing and sexual reproduction (Valle, 1986). Risso-Pascotto et al (2009a) observed meiotic abnormalities at a low frequency in two hexaploid accessions of Brachiaria dura, as well as a few multivalent chromosome associations at diakinesis, and suggested that hexaploidy probably resulted from chromosome doubling. The accumulated evidence from several studies on Brachiaria point to an association between polyploidy and apomixis, with irregular meiosis, on the one hand, and sexual reproduction and regular chromosome pairing on the other (Valle and Savidan, 1996;Valle and Pagliarini, 2009).…”

Section: Discussionmentioning

confidence: 96%

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.

View full text Add to dashboard Cite

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.

show abstract

Chromosome number and microsporogenesis of two accessions of Brachiaria dura Stapf (Poaceae)

Cited by 10 publications

References 9 publications

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

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

Meiotic abnormalities in sugarcane (Saccharum spp.): Evidence for peri- and paracentric inversions

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

Contact Info

Product

Resources

About