scholarly journals Meiotic analysis in induced tetraploids of Brachiaria decumbens Stapf

2011 ◽  
Vol 11 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Carine Simioni ◽  
Cacilda Borges do Valle
Keyword(s):  
Chromosome Segregation ◽  
Pollen Fertility ◽  
Interspecific Hybrids ◽  
Somatic Chromosome ◽  
Breeding Program ◽  
Meiotic Behavior ◽  
Brachiaria Decumbens ◽  
Meiotic Analysis ◽  
Chromosome Duplication

The meiotic behavior of three tetraploid plants (2n=4x=36) originated from somatic chromosome duplication of sexually reproducing diploid plants of Brachiaria decumbens was evaluated. All the analyzed plants presented abnormalities related to polyploidy, such as irregular chromosome segregation, leading to precocious chromosome migration to the poles and micronuclei during both meiotic divisions. However, the abnormalities observed did not compromise the meiotic products which were characterized by regular tetrads and satisfactory pollen fertility varying from 61.36 to 64.86%. Chromosomes paired mostly as bivalents in diakinesis but univalents to tetravalents were also observed. These studies contributed to the choice of compatible fertile sexual genitors to be crossed to natural tetraploid apomicts in the B. decumbens by identifying abnormalities and verifying pollen fertility. Intraespecific crosses should reduce sterility in the hybrids produced in the breeding program of Brachiaria, a problem observed with the interspecific hybrids produced so far.

scholarly journals Oligo-painting and GISH reveal meiotic chromosome biases and increased meiotic stability in synthetic allotetraploid Cucumis ×hytivus with dysploid parental karyotypes

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Qinzheng Zhao ◽  
Yunzhu Wang ◽  
Yunfei Bi ◽  
Yufei Zhai ◽  
Xiaqing Yu ◽  
...  
Keyword(s):  
Interspecific Hybridization ◽  
Interspecific Hybrids ◽  
Chromosome Doubling ◽  
Meiotic Chromosome ◽  
Genomic In Situ Hybridization ◽  
Meiotic Behavior ◽  
Cytological Evidence ◽  
Meiotic Stability ◽  
Inbred Family

Abstract Background Meiosis of newly formed allopolyploids frequently encounter perturbations induced by the merging of divergent and hybridizable genomes. However, to date, the meiotic properties of allopolyploids with dysploid parental karyotypes have not been studied in detail. The allotetraploid Cucumis ×hytivus (HHCC, 2n = 38) was obtained from interspecific hybridization between C. sativus (CC, 2n = 14) and C. hystrix (HH, 2n = 24) followed by chromosome doubling. The results of this study thus offer an excellent opportunity to explore the meiotic properties of allopolyploids with dysploid parental karyotypes. Results In this report, we describe the meiotic properties of five chromosomes (C5, C7, H1, H9 and H10) and two genomes in interspecific hybrids and C. ×hytivus (the 4th and 14th inbred family) through oligo-painting and genomic in situ hybridization (GISH). We show that 1) only two translocations carrying C5-oligo signals were detected on the chromosomes C2 and C4 of one 14th individual by the karyotyping of eight 4th and 36 14th plants based on C5- and C7-oligo painting, and possible cytological evidence was observed in meiosis of the 4th generation; 2) individual chromosome have biases for homoeologous pairing and univalent formation in F1 hybrids and allotetraploids; 3) extensive H-chromosome autosyndetic pairings (e.g., H-H, 25.5% PMCs) were observed in interspecific F1 hybrid, whereas no C-chromosome autosyndetic pairings were observed (e.g. C-C); 4) the meiotic properties of two subgenomes have significant biases in allotetraploids: H-subgenome exhibits higher univalent and chromosome lagging frequencies than C-subgenome; and 5) increased meiotic stability in the S14 generation compared with the S4 generation, including synchronous meiosis behavior, reduced incidents of univalent and chromosome lagging. Conclusions These results suggest that the meiotic behavior of two subgenomes has dramatic biases in response to interspecific hybridization and allopolyploidization, and the meiotic behavior harmony of subgenomes is a key subject of meiosis evolution in C. ×hytivus. This study helps to elucidate the meiotic properties and evolution of nascent allopolyploids with the dysploid parental karyotypes.

MUTAGENICITY OF SOME COMMON PESTICIDES IN BARLEY

1980 ◽  
Vol 22 (2) ◽  
pp. 260-260 ◽  
Author(s):  
I. S. Grover ◽  
P. S. Tyagi
Keyword(s):  
Chromosomal Aberrations ◽  
Pollen Fertility ◽  
Present Report ◽  
Test Material ◽  
Root Tip ◽  
Unequal Distribution ◽  
Meiotic Analysis ◽  
Barley Grains ◽  
Tip Cells ◽  
Root Tip Cells

The perusual of literature reveals the desirability to screen the mutagenicity of pesticides. The present report deals with the cytological aberrations and chlorophyll mutations induced by Thiodan, Folithion, Lebaycid and Kitazin, employing barley as the test material. The chromosomal aberrations were examined both at mitotic and meiotic level. The root tip cells from pesticide treated barley grains revealed various abnormalities at metaphase including fragmentation, unequal chromosome, chromosomes with displaced satellite and increased number of chromosome. The laggards, bridges, tripolarity, tetrapolarity and micronuclei were seen at later stages. A positive correlation between dose and aberration was noticed. The meiotic analysis of PMC's from plants raised from pesticide treated barley grains, revealed quadrivalents and univalents at metaphase-I. Anaphase-I was atypical in having unequal distribution, laggards, bridges — single or double. The persistent bridges at telophase and micronuclei were not unfrequent. The pollen fertility was reduced. — M2 analysis at the seedling stage revealed albina, xantha and tigrina mutants. The tigrina's were more frequent. Lebaycid was the most effective while Thiodan was the most efficient.

scholarly journals Characterization and selection of interspecific hybrids of Brachiaria decumbens for seed production in Campo Grande - MS

2016 ◽  
Author(s):  
Lenise Castilho Monteiro ◽  
Jaqueline Rosemeire Verzignassi ◽  
Sanzio Carvalho Lima Barrios ◽  
Cacilda Borges do Valle ◽  
Celso Dornelas Fernandes ◽  
...  
Keyword(s):  
Seed Production ◽  
Interspecific Hybrids ◽  
Brachiaria Decumbens ◽  
Selection Of

scholarly journals Selection of interspecific Psidium spp. hybrids resistant to Meloidogyne enterolobii

2019 ◽  
Vol 41 ◽  
pp. e42702 ◽  
Author(s):  
Rodrigo Moreira Ribeiro ◽  
Vicente Martins Gomes ◽  
Alexandre Pio Viana ◽  
Ricardo Moreira Souza ◽  
Paulo Ricardo dos Santos
Keyword(s):  
Interspecific Hybrids ◽  
Genetic Parameters ◽  
Breeding Program ◽  
Economic Losses ◽  
Sources Of Resistance ◽  
Production Chain ◽  
Meloidogyne Enterolobii ◽  
Indirect Economic Losses ◽  
Selection Of

Since 2001, the disease known as 'guava decline', resulting from the interaction between the phytonematode Meloidogyne enterolobii and the fungus Fusarium solanie, has caused direct and indirect economic losses to the entire guava production chain. Given the lack of sources of resistance in guava genotypes, interspecific hybrids of Psidium spp. were obtained for resistance to the nematode M. enterolobii. To classify the level of resistance of the interspecific hybrids, we evaluated the plant classification methodologies proposed by Oostenbrink (1966) and Moura and Régis (1987). Estimates of genetic parameters were obtained using the REML/BLUP approach. Interspecific hybrids resistant to M. enterolobii were selected that can be used as rootstocks or in new crosses for the development of the guava breeding program.

scholarly journals Meiotic behavior of several Brazilian soybean varieties

2000 ◽  
Vol 23 (3) ◽  
pp. 623-631 ◽  
Author(s):  
Nilton Cesar Pires Bione ◽  
Maria Suely Pagliarini ◽  
José Francisco Ferraz de Toledo
Keyword(s):  
Chromosome Segregation ◽  
Pollen Fertility ◽  
Low Frequency ◽  
Model System ◽  
Meiotic Abnormalities ◽  
Standard Methods ◽  
Cytogenetic Studies ◽  
Glycine Max L ◽  
Chromosome Stickiness ◽  
Apparent Similarity

Despite the importance of soybeans little cytogenetic work has traditionally been done, due to the small size and apparent similarity of the chromosomes. Fifteen soybean [Glycine max (L.) Merrill] varieties adapted for cultivation in two distinct regions of Brazil were analyzed cytogenetically. A low frequency of meiotic abnormalities was noted in all varieties, although they were not equally affected. Irregular chromosome segregation, chromosome stickiness, cytoplasmic connections between cells, cytomixis and irregular spindles were the main abnormalities observed, none of which had been described previously in soybeans. All of these abnormalities can affect pollen fertility. Pollen fertility was high in most varieties and was correlated with meiotic abnormalities. Although soybean is not a model system for cytological studies, we found that it is possible to conduct cytogenetic studies on this species, though some modifications in the standard methods for meiotic studies were necessary to obtain satisfactory results.

scholarly journals Meiotic behavior of interspecific hybrids between artificially tetraploidized sexual Brachiaria ruziziensis and tetraploid apomictic B. brizantha (Poaceae)

2010 ◽  
Vol 67 (2) ◽  
pp. 191-197 ◽  
Author(s):  
Mariana Ferrari Felismino ◽  
Maria Suely Pagliarini ◽  
Cacilda Borges do Valle
Keyword(s):  
Nutritive Value ◽  
Production Systems ◽  
Genetic Recombination ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Breeding Program ◽  
Meiotic Behavior ◽  
Brachiaria Ruziziensis ◽  
Sexual Hybrid

The meiotic behavior of four interspecific promising hybrids was evaluated by conventional cytological methods. The female genitors were two artificially tetraploidized sexual accessions of B. ruziziensis (R41 and R44, 2n = 4χ = 36), which were crossed to an agronomically superior natural tetraploid apomictic genotype of B. brizantha (B140 - BRA003395). Three of them (HBGC313, HBGC 315, and HBGC324) were sexual and one (HBGC325) apomictic. Analyses of some cells in diakinesis revealed multivalent chromosome configurations, suggesting that genetic recombination and introgression of some genes could be present. The four hybrids had different types of meiotic abnormalities at various frequencies. Abnormalities related to irregular chromosome segregation due to polyploidy were common among these hybrids, and characterized by precocious chromosome migration to the poles, laggard chromosomes, both generating micronuclei in telophases and tetrads and, as a consequence, unbalanced gametes. One abnormality genotype-specific, related to spindle orientation (a putative divergent spindle mutation), was recorded for the first time in two of the hybrids, HBGC313 and HBGC325. The sexual hybrid HBGC324 had the lower rate of abnormalities, and it could be used as a female genitor in future crosses in the breeding program. The abnormalities present in these hybrids may impact fertility and affect seed production. Based on the results, HBGC324 is the single hybrid recommended to the breeding program. Hybrids must produce a good amount of viable seeds, besides good overall dry matter production and nutritive value, in order to be widely utilized and adopted in production systems. Due to pseudogamy, the desirable superior apomictic hybrids need viable pollen grains to fertilize the secondary nucleus of the embryo sac and thus ensure normal and vigorous endosperm development and plenty of seed set.

scholarly journals Meiotic Behavior, Pollen Fertility and Seed Production in Brazilian Populations of Centella asiatica (L.) Urban (Umbelliferae).

CYTOLOGIA ◽  
1996 ◽  
Vol 61 (4) ◽  
pp. 375-381 ◽  
Author(s):  
Márcia Edilaine Lopes Consolaro ◽  
Maria Suely Pagliarini ◽  
Lázaro José Chaves
Keyword(s):  
Seed Production ◽  
Pollen Fertility ◽  
Centella Asiatica ◽  
Meiotic Behavior ◽  
Brazilian Populations
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