Chromosome numbers and microsporogenesis in Brachiaria brizantha (Gramineae)

被引：68

作者：

Mendes-Bonato A.B. ^{[1
]}

Pagliarini M.S. ^{[1
]}

Forli F. ^{[1
]}

Borges Do Valle C. ^{[2
]}

De Oliveira Penteado M.I. ^{[3
]}

机构：

[1] Department of Cell Biology and Genetics, State University of Maringá

[2] Embrapa Beef Cattle, Campo Grande - MS 79002-970

[3] Embrapa, Intellectual Property, Parque Estação Biológica

来源：

Euphytica | 2002年 / 125卷 / 3期

关键词：

Apomixis; Brachiaria brizantha; Chromosome number; Grasses; Meiotic behavior; Polyploidy;

D O I：

10.1023/A:1016026027724

中图分类号：

学科分类号：

摘要：

The genus Brachiaria, native to the African tropical savannas, has achieved significance as a pasture grass in many tropical and subtropical countries, including Brazil. Many species and accessions are polyploid and apomictic, which complicates the improvement of breeding stocks through hybridization. In support of breeding programs, cytogenetic characterization, including chromosome counts and evaluation of the meiotic behavior in the accessions of the Brachiaria has been undertaken at the Embrapa Beef Cattle Center. In this study, 22 accessions of B. brizantha were analyzed of which one was found to be diploid (2n = 2x = 18), 18 were tetraploid (2n = 4x = 36) and three were hexaploid (2n = 6x = 54). The meiotic chromosome behavior was slightly irregular in the diploid and in some tetraploid accessions, and highly irregular in most tetra- and hexaploid accessions. Meiotic abnormalities were those common to polyploidy, i.e., multivalent chromosome association at diakinesis and irregular chromosome segregation leading to micronuclei formation in the tetrad stage. Low frequencies of multivalent chromosome associations among polyploids suggest that they may be segmental allopolyploids.

引用

页码：419 / 425

页数：6

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