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Brachiaria; Breeding program; Microsporogenesis; Sexual hybrids

Three sexual interspecific hybrids of Brachiaria (HBGC076, HBGC009, and HBGC014) resulting from crosses between B. ruziziensis (female genitor) and B. decumbens and B. brizantha (male genitors) produced by Embrapa Beef Cattle in the 1980s were cytologically analyzed by conventional methods for meiotic studies. The cytogenetic analysis showed the ... more

V.A. Fuzinatto; M.S. Pagliarini; C.B. Valle
Brachiaria humidicola; Breeding program; Cytokinesis; Forage grass; Microsporogenesis

Microsporogenesis was evaluated in the Brachiaria humidicola collection of the Embrapa Beef Cattle Center, represented by 60 accessions. One accession (H121) presented an abnormal pattern of cytokinesis that had never been reported in this genus. Among 900 meiocytes analyzed in the first division, 10.7% underwent precocious and multiple cytokinesis in metaphase I, ... more

E.V. Adamowski; K.R. Boldrini; M.S. Pagliarini; C.Bdo Valle
Basic chromosome number; Brachiaria dictyoneura; Cell fusion; Cytokinesis; Interspecific hybridization; Microsporogenesis

Microsporogenesis was analyzed in five accessions of Brachiaria dictyoneura presenting x = 6 as the basic chromosome number. All accessions were tetraploid (2n = 4x = 24) with chromosome pairing in bi-, tri-, and quadrivalents. The recorded meiotic abnormalities were those typical of polyploids, including precocious chromosome migration to the poles, laggard chromosomes, and ... more

C. Risso-Pascotto; M.S. Pagliarini; C.B. Valle
Allopolyploidy; Brachiaria brizantha; Forage grass; Microsporogenesis; Pollen viability

In the hexaploid (2n = 6x = 54) accession B176 of Brachiaria brizantha, one cytological characteristic differentiated it from the other accessions previously analyzed with the same ploidy level. Nearly 40% of meiocytes displayed the chromosome set arranged at two metaphase plates at the poles of the cell, close to the membrane. In these cells, both metaphase plates were ... more

C. Risso-Pascotto; D.V. Mendes; N. Silva; M.S. Pagliarini; C.B. Valle
Brachiaria; environment; interspecific hybrid; Microsporogenesis

Microsporogenesis in an interspecific Brachiaria hybrid, grown in the field under natural environmental conditions in Brazilian savannas, was analyzed in three distinct years of collection. Several types of meiotic abnormalities were recorded during those three years, but varied in type and frequency depending on the year. The average temperature and rainfall 15 days before collection ... more

V.A. Fuzinatto; M.S. Pagliarini; C.B. Valle
Brachiaria decumbens; Evolution; Genome elimination; Microsporogenesis; Natural hybridization; Polyploidy

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. ... more

G.C.L. Ricci; M.S. Pagliarini; C.B. Valle
Brachiaria brizantha; Breeding; Forage grass; Microsporogenesis

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 ... more

M.S. Pagliarini; C.B. Valle; E.M. Santos; D.V. Mendes; Z.H. Bernardo; A.B. Mendes-Bonato; N. Silva; V. Calisto
Cytomixis; Houttuynia cordata; Meiosis; Microsporogenesis; Polyploidy

Houttuynia cordata (Saururaceae) is a leaf vegetable and a medicinal herb througout much of Asia. Cytomixis and meiotic abnormalities during microsporogenesis were found in two populations of H. cordata with different ploidy levels (2n = 38, 96). Cytomixis occurred in pollen mother cells during meiosis at high frequencies and with variable degrees of chromatin/ ... more

J.Z. Guan; J.J. Wang; Z.H. Cheng; Y. Liu; Z.Y. Li
Cytomixis; Meiosis; Microsporogenesis; Pinellia ternata; Polyploidy

Pinellia ternata is an important traditional Chinese medicinal plant. Its different populations in China have various ploidy levels, based on x = 13, as well as extensive aneuploid series. The microsporogenesis process was observed in specimens from three populations from three regions of Hubei Province; they were characterized by normal and abnormal meiotic divisions in ... more

Y. Liu; R.K. Hui; R.N. Deng; J.J. Wang; M. Wang; Z.Y. Li
B chromosome; Chiasma distribution; Chiasma frequency; Meiotic behavior; Popcorn

Cytological analysis of microsporogenesis in 72 popcorn plants, comprising nine from the original population (CMS-43, S0) and 63 from seven cycles of self-fertilization (S1 to S7), one plant of S0 generation (plant 2) was identified with B chromosomes. The number of B chromosomes varied from two to three in the same anther. The pattern of chromosome ... more

G.L. Ricci; N. Silva; M.S. Pagliarini; C.A. Scapim