scholarly journals Morphology and Meiotic Behavior of Three Dendrobium Amphidiploids and Their Diploid Counterparts

HortScience ◽  
1993 ◽  
Vol 28 (9) ◽  
pp. 935-937 ◽  
Author(s):  
James McConnell ◽  
H. Kamemoto
Keyword(s):  
Small Chromosome ◽  
Chromosome Size ◽  
Meiotic Behavior ◽  
Preferential Pairing ◽  
Bivalent Formation ◽  
Metaphase I

Floral characteristics, meiotic behavior, and sporad formation were compared in three Dendrobium tetraploids (amphidiploids) and their diploid counterparts. Amphidiploid flowers were larger than those of diploids. Diploid meiotic behavior varied; mean configurations at Metaphase I ranged from 14.3 bivalents and 9.4 univalents to 18.9 bivalents and 0.2 univalents. In amphidiploids, nearly all cells had 38 bivalents. Sporad formation also varied; diploids had 36% to 70% tetrads and amphidiploids had 97% to 100% tetrads. Preferential pairing and small chromosome size may promote bivalent formation in amphidiploids.

Chromosome size, morphology, and gene density determine bivalent positioning in metaphase I human spermatocytes

2014 ◽  
Vol 101 (3) ◽  
pp. 818-824.e3 ◽  
Author(s):  
Laia Vergés ◽  
Joan Blanco ◽  
Oliver Valero ◽  
Francesca Vidal ◽  
Zaida Sarrate
Keyword(s):  
Gene Density ◽  
Chromosome Size ◽  
Metaphase I

THE IDENTIFICATION AND MEIOTIC BEHAVIOR OF A DITELOSOMIC LINE IN AVENA SATIVA L

1970 ◽  
Vol 12 (4) ◽  
pp. 876-881 ◽  
Author(s):  
J. P. Dubuc ◽  
R. C. McGinnis
Keyword(s):  
Avena Sativa ◽  
Reciprocal Translocation ◽  
Meiotic Behavior ◽  
Telocentric Chromosome ◽  
Chromosome 20 ◽  
Ditelosomic Line ◽  
Metaphase I

A ditelosomic line was crossed with 12 identified monosomics. The metaphase I pairing was studied in the 40 + t – chromosome progenies. The telocentric chromosome was found to be homologous to the three previously identified monosomics namely, −7, −10, and −20 suggesting that the same chromosome is missing in all three lines. None of the chromosomes in monosomic condition used in the crosses except ST-7 and ST-17 from A. byzantina were involved in the reciprocal translocation present between Sun II and Garry and Rodney.The gene for normal vs. abaxial curling of the leaves was located on the short arm of chromosome 20. The genes for diploidisation and normal vs. kinky neck were located on 20L.

scholarly journals The intranuclear relationship between centromere volume and chromosome size in Festuca scariosa X drymeja

1981 ◽  
Vol 47 (1) ◽  
pp. 117-125
Author(s):  
G. Jenkins ◽  
M.D. Bennett
Keyword(s):  
Serial Section ◽  
Chromosome Length ◽  
Individual Chromosome ◽  
Chromosome Size ◽  
Preferential Pairing ◽  
Frequency Distributions ◽  
Positive Correlation ◽  
Serial Section Reconstruction

In the hybrid Festuca scarisoa X drymeja where pairing is incomplete at pachytene, there is preferential pairing between the longer chromosomes of the complement. EM serial-section reconstruction of nuclei at zygotene and pachytene reveals that there is equally pronounced preferential pairing between larger centromeres. This evidence suggests that the longer chromosomes have large centromeres and that centromere volume is correlated with chromosome length. Confirmation of this comes from the comparison of the frequency distributions of observed centromere volumes and those predicted on the basis of chromosome length. Although there is a positive correlation between centromere volume and chromosome length, it is not possible to identify the centromeres of each individual chromosome within the complement because (a) the differences between the lengths of each chromosome are small and (b) the estimates of relative centromere volumes vary significantly between cells.

scholarly journals Chromosome Number and Meiotic Behavior of Cultivated Chia, Salvia hispanica (Lamiaceae)

HortScience ◽  
1990 ◽  
Vol 25 (12) ◽  
pp. 1646-1647 ◽  
Author(s):  
A. Estilai ◽  
A. Hashemi ◽  
K. Truman
Keyword(s):  
Chromosome Number ◽  
Species Identification ◽  
Southern California ◽  
Herbarium Specimens ◽  
Meiotic Behavior ◽  
Root Tips ◽  
Chromosome Counts ◽  
Salvia Hispanica ◽  
Meiotic Analyses ◽  
Metaphase I

Edible chia seeds, purchased from the local markets in Guatemala, Mexico, and southern California, were used for species identification, chromosome counts, karyotype construction, and meiotic analyses. Plants raised from those seeds had ovate leaves, dense racemose inflorescences, pale-blue flowers, and were identified from herbarium specimens as Salvia hispanica L. Mitotic analyses of root tips from 50 plants showed 2n = 12—the lowest chromosome number in the genus. Chromosomes were small, ranging from 2 to 3.5 pm. One pair of chromosomes was metacentric (with the long arm: short arm ratio, r = 1.5), four pairs were submetacentric (r = 2.6 to 3.6), and one pair was telocentric (r = 12). Meiosis was regular and six bivalents were observed at metaphase I. Ring and rod bivalents averaged 1.53 ± 1.05 and 4.47 ± 1.05, respectively;

CYTOGENETIC, ECOLOGIC AND MORPHOLOGIC STUDIES IN BRAZILIAN FORMS OF PASPALUM DILATATUM

1968 ◽  
Vol 10 (1) ◽  
pp. 131-138 ◽  
Author(s):  
M. Irene B. De Moraes Fernandes ◽  
I. L. Barreto ◽  
F. M. Salzano
Keyword(s):  
Meiotic Behavior ◽  
Paspalum Dilatatum ◽  
Wide Range ◽  
Somatic Number ◽  
The Common ◽  
Metaphase I

The somatic number, meiotic behavior, morphology and ecology of five forms of Paspalum dilatatum Poir are reported. The sexual type yellow anther (2n = 40) showed essentially regular meiotic behavior. The common form (2n = 50) presented 20 II and 10 I in about 85% of the cells studied at diakinesis and metaphase I. Pauciciliatum (2n = 40) and Uruguaiana (2n = 60) showed a wide range of chromosome configurations at these stages; finally, Torres presented uniformly 60 univalents. These results are compared with morphologic and ecologic data and some suggestions about the possible mode of origin of these forms are presented.

Meiotic configurations in the oospore of Phytophthora capsici

1974 ◽  
Vol 52 (10) ◽  
pp. 2141-2143 ◽  
Author(s):  
L. W. Stephenson ◽  
D. C. Erwin ◽  
J. V. Leary
Keyword(s):  
Phytophthora Capsici ◽  
Nuclear Size ◽  
Chromosome Size ◽  
Haploid Number ◽  
Whole Mounts ◽  
Metaphase I

Photomicrographs of chromosomal configurations in nuclei of squashed whole mounts of mature oospores (cultures 32 days old) of Phytophthora capsici stained with iron hematoxylin were interpreted to indicate that meiosis occurred in the oospore. Chromosomes in dividing oospore nuclei were observed in synapsis, diakinesis, metaphase I, and metaphase II. Comparison of polar metaphase I and metaphase II plates revealed a reduction in chromosome size and number and nuclear size. The haploid number of chromosomes was interpreted to be 6.

Chromosome pairing in hybrids of ph1b mutant wheat with rye

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 639-646 ◽  
Author(s):  
T. Naranjo ◽  
A. Roca ◽  
R. Giraldez ◽  
P. G. Goicoechea
Keyword(s):  
Common Wheat ◽  
Chromosome Pairing ◽  
Chromosome Structure ◽  
Preferential Pairing ◽  
C Banding ◽  
Homoeologous Chromosomes ◽  
Metaphase I

Metaphase I pairing was studied in five ph1b mutant wheat × rye hybrids to verify the presence of translocations between homoeologous chromosomes in ph1b mutant wheat and to establish the pairing homoeology between wheat and rye chromosomes. Three 5B-deficient ABDR hybrids with standard chromosome structure were used as controls. Chromosomes 1R and 5R of rye and most wheat chromosomes, as well as their arms, were identified by means of C-banding. The presence of 5BS in ph1b hybrids raised the overall pairing level. The pattern of pairing between wheat chromosomes in ph1b hybrids, as in 5B-deficient hybrids, was characterized by the occurrence of preferential pairing between chromosomes of the A and D genomes in most homoeologous groups. The existence of a double translocation involving 4BL, 5AL, and 7BS in common wheat was confirmed. Deviation from the standard pairing pattern suggested the existence of a translocation involving 1BL and 1DL in one ph1b ABDR plant and another translocation involving 3AL and 3DL in three other ph1b hybrids. In ph1b hybrids, wheat – rye pairing was relatively frequent for 1RL, 5RL, and an arm of a metacentric rye chromosome, probably 2R, that is homoeologous to 2BL, and the homoeologous arms of 2A and 2D. The existence of a translocation involving 5RL and 4RL in rye was confirmed.Key words: homoeologous, homologous, 5B-deficient, translocations, C-banding.

Relationship between pachytene synapsis, metaphase I associations, and transmission of 2B and 4B chromosomes in rye

Genome ◽  
2000 ◽  
Vol 43 (2) ◽  
pp. 232-239 ◽  
Author(s):  
Guillermo Jiménez ◽  
Silvia Manzanero ◽  
María J Puertas
Keyword(s):  
Secale Cereale ◽  
Maternal Effect ◽  
Chiasma Frequency ◽  
Transmission Rate ◽  
Chiasma Formation ◽  
B Chromosomes ◽  
Bivalent Formation ◽  
The Relationship ◽  
Variable Efficiency ◽  
Metaphase I

2B rye plants selected for high (H) or low (L) B transmission rate were studied at pachytene and metaphase I of meiosis to determine the relationship between synapsis, bivalents at metaphase I, and B transmission rate. The results show that the 2 B chromosomes (Bs) form bivalents at pachytene in both the H and L lines, whereas the frequency of bivalents at metaphase I is much higher in the H than in the L line. This demonstrates that B transmission is mainly related to the proper association of Bs at metaphase I, as well as that synapsis of the 2 Bs in the L line is normal, but the bivalent is not consolidated by a chiasma in most cases. Crosses were made between 2B plants of the H and L lines in all combinations (H × H, H × L, L × H, and L × L) to obtain 4B plants. Similarly, bivalent formation at pachytene and metaphase I was studied. The results show that 4B plants of the H × H and L × L classes differ significantly at pachytene and metaphase I since the former forms more bivalents. The heterozygous 4 Bs of the H × L and L × H classes show intermediate values. The relation H × H > H × L > L × H > L × L was consistently found for the variables transmission rate, bivalents at pachytene, bivalents at metaphase I, and B mean chiasma frequency. A maternal effect was also found. Our data suggest that there are two separate mechanisms acting upon synapsis and chiasma formation in H and L B chromosomes: (i) there is variable efficiency of the control of synapsis at early stages of meiosis; and (ii) there is variable efficiency of the control of the number of chiasmata. Key words: B chromosomes, synaptonemal complex, Secale cereale.

Diploid-like meiotic behavior in synthesized amphiploids of the genus Glycine Willd. subgenus Glycine

1985 ◽  
Vol 27 (6) ◽  
pp. 655-660 ◽  
Author(s):  
R. J. Singh ◽  
T. Hymowitz
Keyword(s):  
Chromosomal Instability ◽  
Interspecific Hybrids ◽  
Meiotic Behavior ◽  
Preferential Pairing ◽  
Homologous Chromosomes ◽  
Tetraploid Hybrid

Six amphiploids consisting of one allotetraploid (2n = 4x = 80), four allohexaploids (2n = 6x = 120), and one allooctoploid (2n = 8x = 160) were synthesized by doubling the chromosomes of F1 interspecific hybrids of the following parents: one diploid (Glycine latifolia 2n = 2x = 40 × G. clandestina, short pod (Sp), 2n = 2x = 40); four triploids (G. clandestina, Sp, 2n = 2x = 40 × G. tabacina 2n = 4x = 80), (G. tabacina 2n = 4x = 80 × G. canescens 2n = 2x = 40), (G. tomentella2n = 4x = 80 × G. canescens 2n = 2x = 40 and its reciprocal); and one tetraploid (G. tomentella2n = 4x = 80 × G. tabacina 2n = 4x = 80). Chromosomal chimerism was observed in the C1 generation. Pod set was recorded in all the colchicine-treated hybrids except in the tetraploid hybrid of G. tomentella × G. tabacina. In C2 generation plants, chromosomal instability was noticed only in the allohexaploid of G. tabacina × G. canescens. All of the amphiploids showed diploid-like meiosis in the majority of the sporocytes and did not exhibit expected multivalent associations, a classical example of allopolyploidy. This was attributed to strong preferential pairing between homologous chromosomes which may be under genetic control.Key words: Glycine, synapsis, interspecific hybrids.

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