Cytomixis in Agropyron cristatum

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 765-769 ◽  
Author(s):  
Gary R. Bauchan ◽  
Li-Ching Wang Linkous ◽  
William Tai
Keyword(s):  
Aqueous Solution ◽  
Key Words ◽  
Chromosome Complement ◽  
Agropyron Cristatum ◽  
Pollen Mother Cells ◽  
Meiotic Irregularities ◽  
Treated Plant ◽  
Mother Cells

An Agropyron cristatum plant (CB-9-41), crested wheat grass, and its vegetative clones have been identified that contain pollen mother cells that have a gain or a loss in chromatin (DNA). CB-9-41 was identified during the course of an experiment to determine the effectiveness of colchicine on the doubling of the chromosome complement. The seeds that produced this plant were presoaked and then treated with a 0.1% aqueous solution of colchicine for 12 h. All stages of meiosis were studied in the original colchicine-treated plant and three vegetative clones that were obtained 17 years later. Approximately 40% of the pollen mother cells had meiotic irregularities. These irregularities were caused by multipolar meiosis (23%), precocious separation of bivalents at metaphase (8%), inversions (6%), and cytomixis (11%). The gain or loss of chromatin occurred as a result of cytomixis. Key words: crested wheat grass, extragenomic chromatin, multipolar meiosis, colchicine.

Persisting demibivalents: a unique meiotic behaviour in Cuscuta babylonica Choisy

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Batia Pazy ◽  
Uzi Plitmann
Keyword(s):  
Key Words ◽  
Chromosome Segregation ◽  
Meiotic Behaviour ◽  
Chromosome Behaviour ◽  
Chromosome Movement ◽  
Pollen Mother Cells ◽  
Key Words Meiosis ◽  
Mother Cells ◽  
Telomeric Association

Idiosyncratic chromosome behaviour during meiosis was found in pollen mother cells of Cuscuta babylonica Choisy, a thread-like holoparasitic herb. Its main features are among the following: (i) telomeric association between homologues through most stages of the process, which leads to persisting chromatid bivalents (= "demibivalents"); (ii) uncommon chromosome segregation in first and second anaphase; and (iii) prolonged intensified heterochromatinization. Although "regular" in its own way, this process leads to the formation of unviable products. Its further investigation might contribute to our understanding of the role of the spindle and chromosome movement in the ordinary process of meiosis. Key words: meiosis (abnormal), persisting demibivalents, Cuscuta babylonica.

scholarly journals Development of pollinium in Malaxis muscifera (Lindl.) Kuntze

1970 ◽  
Vol 39 (2) ◽  
pp. 193-198
Author(s):  
Ravi Kant ◽  
MM Hossain
Keyword(s):  
Key Words ◽  
Vegetative Cell ◽  
Middle Layer ◽  
Cell Degeneration ◽  
Pollen Mother Cells ◽  
Meristematic Cells ◽  
Different Types ◽  
Mother Cells ◽  
Hypodermal Layer

Anther primordium of Malaxis muscifera (Lindl.) Kuntze initiated as a homogenous mass of meristematic cells is surrounded by protoderm. Two thecae are oriented towards the labellum, each of them consisted of a mass of archesporial cells. The hypodermal layer of sporogenous cells divide periclinally to form an endothecial, a middle layer and a tapetum. Pollen mother cells formed different types of microspore tetrads. Each microspore divides mitotically resulting a generative and a vegetative cell. Degeneration of the sterile septum resulted four naked and clavate pollinia. Key words: Malaxis muscifera; Anther; Pollinium; Morphogenesis DOI: 10.3329/bjb.v39i2.7480 Bangladesh J. Bot. 39(2): 193-198, 2010 (December)

Nucleolus organization and meiotic behaviour of B chromosomes in Hepatica nobilis

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 853-859 ◽  
Author(s):  
T. Mabuchi
Keyword(s):  
Chromosome Complement ◽  
B Chromosomes ◽  
The Other ◽  
Chromosome 7 ◽  
Meiotic Behaviour ◽  
Pollen Mother Cells ◽  
Small Satellites ◽  
C Banding ◽  
End To End ◽  
Mother Cells

The C-banding karyotype of Hepatica nobilis indicates the A chromosome complement and B chromosomes (Bs) to be banded in the terminal regions. The A chromosomes (As) of this species comprise mainly euchromatin (89.7%) and a small amount of heterochromatin (10.3%). Bs of H. nobilis have terminal centromeres at one end and possess small satellites at the other end. Bs cause an increase in the number of nucleoli per cell, with a decrease in the size of each nucleolus. During meiosis, Bs associate as bivalents and multivalents up to pentavalents. These associate loosely with the short arm of satellited chromosome 7 (end to end association) at diakinesis in some pollen mother cells. Bivalent or trivalent Bs associate with a nucleolus at diakinesis. B chromosomes of H. nobilis thus appear to contain nucleolus organizing regions and may have originated from the satellited chromosome 7 and other members of As.Key words: Hepatica, satellited B, end to end association, origin, nucleolus organizing regions.

CRESTED WHEATGRASS COMPLEX

1956 ◽  
Vol 34 (3) ◽  
pp. 328-345 ◽  
Author(s):  
P. Sarkar
Keyword(s):  
Chromosome Number ◽  
High Frequency ◽  
Secondary Constriction ◽  
Agropyron Cristatum ◽  
Crested Wheatgrass ◽  
Pollen Mother Cells ◽  
Mother Cells

In the complex of taxa commonly called crested wheatgrasses, at least five species can be distinguished according to descriptions by Nevski in the Flora of the U.S.S.R. These are: Agropyron cristatum, A. pectiniforme, A. desertorum, A. michnoi, and A. sibiricum. Of the two commercial forms of A. cristatum, 'Standard' and 'Fairway', the latter is diploid with 2n = 14. From a consideration of its chromosome number and morphological distinctness this taxon is here given specific status with the name Agropyron cristatiforme. Each of the five other species mentioned above is tetraploid with 2n = 28. Karyomorphologically all the species of Agropyron studied here are characterized by chromosomes with median or submedian centromeres and by the lack of any secondary constriction or satellite. A high frequency of multivalents in the pollen mother cells of A. michnoi and A. sibiricum indicates an autoploid derivation of these two species.

Meiotic irregularities in hexaploid oats I. Univalent frequencies in spring × winter variety hybrids of Avena sativa

1947 ◽  
Vol 37 (2) ◽  
pp. 139-144 ◽  
Author(s):  
H. W. Hoeard
Keyword(s):  
Avena Sativa ◽  
Pollen Mother Cells ◽  
Meiotic Irregularities ◽  
Mother Cells

1. Meiosis was studied in pollen mother cells of the following F1 hybrids: Victory × Avoine d’hiver, Victory × Grey Winter, Argentine × Avoine d’hiver, Victory × Argentine and Avoine d’hiver × Grey Winter.

Meiotic irregularities in hexaploid oats. III. Further observations on the frequency of univalents and other meiotic irregularities in spring × winter variety hybrids of Avena sativa

1955 ◽  
Vol 45 (3) ◽  
pp. 380-387 ◽  
Author(s):  
A. B. Joshi ◽  
H. W. Howard
Keyword(s):  
Avena Sativa ◽  
Pollen Mother Cells ◽  
Meiotic Irregularities ◽  
Mother Cells

1. The two spring oat varieties, Argentine and Victory, and the two winter varieties, Grey Winter and Black Winter, have 0.10, 0.07, 1.57 and 0.41% pollen mother cells with irregular meioses respectively.2. F1Victory x Argentine had 3.43% of irregular meioses, and F1. Grey Winter x Black Winter 1.58%.

Meiotic irregularities in hexaploid oats IV. Hybrids between Avena sativa (spring and winter varieties) A. fatua, A. sterilis, A. byzantina and A. nuda

1955 ◽  
Vol 46 (2) ◽  
pp. 183-190 ◽  
Author(s):  
A. B. Joshi ◽  
H. W. Howard
Keyword(s):  
Avena Sativa ◽  
High Frequency ◽  
Asia Minor ◽  
Plant Breeder ◽  
High Frequencies ◽  
Pollen Mother Cells ◽  
Spring Variety ◽  
Meiotic Irregularities ◽  
Close Relationship ◽  
Mother Cells

1. Pollen mother cells with irregularities of meiosis were rare in the parent species and varieties, being usually less than 0·5% and the highest found being only 1·57% in the variety Grey Winter.2. F1A. fatua C.S. 473 (from Afghanistan) × Grey Winter had 33·5% of pollen mother cells with irregularities. On the other hand, the F1 hybrids of A. fatua (C.S. 46 (from Asia Minor) × both spring and winter varieties of A. sativa showed between 2·45 and 12·81% of irregular cells and were thus more regular than F1 spring variety of A. sativa × Grey Winter.3. F1A. sterilis × spring and winter varieties of A. sativa showed between 5·56 and 6·67% of cells with irregularities of meiosis.4. F1A. fatua C.S.46 × A. sterilis and F1A. nuda × A. sterilis had 5·65 and 7·60% of irregular cells respectively, but F1A. nuda × A.fatua C.S. 46 had 46·05%.5. All F1 hybrids with A. byzantina as one parent had high frequencies of pollen mother cells (from 59·12 to 88·45%).6. The commonest irregularity of meiosis was the occurrence of univalents. Multivalents were found at a high frequency only in the A. byzantina hybrids. Bridges and fragments were uncommon, occurring in not more than 2% of cells.7. The limitations of the cytological results in assessing the relationships between the different hexaploid species of oats are discussed. It would, however, appear that there is a close relationship between A. sativa (both spring and winter varieties), A.fatua (C.S. 46) and A. sterilis, but that A. byzantina is not closely related to that group.8. The importance of the results to the plant breeder is briefly indicated.

The chromosomal location of a gene (msg) affecting megasporogenesis in durum wheat

Genome ◽  
1987 ◽  
Vol 29 (4) ◽  
pp. 578-581 ◽  
Author(s):  
L. R. Joppa ◽  
N. D. Williams ◽  
S. S. Maan
Keyword(s):  
Durum Wheat ◽  
Key Words ◽  
Chromosomal Location ◽  
Triticum Turgidum ◽  
Wheat Line ◽  
Pollen Mother Cells ◽  
Chromosome Arm ◽  
Pollen Nucleus ◽  
Mother Cells ◽  
Metaphase I

An aneuploid durum wheat line (Triticum turgidum L. var. durum) having 13 chromosome pairs and 2 unpaired chromosomes at metaphase I of meiosis in pollen mother cells (i.e., monosomic for chromosomes 7A and 7D) was observed to produce some progeny plants with 2n = 40 chromosomes. These aneuploid (triploid) plants were usually weak and sterile. Triploid plants also occurred in the progeny of durum plants monosomic for chromosome 7A, or in progeny of plants that were mono-telodisomic or ditelomonotelosomic for chromosome 7Aq (13 II + 1 t II or 13 II + t II + t I) but not in the progeny of plants ditelomonotelosomic for chromosome 7Ap (13 II + t II + t 1). Therefore, there is a gene(s) on chromosome arm 7Ap that prevents the production of diploid (2n) egg cells in wheat. In the absence of 7Ap, a portion of the egg cells have 26 chromosomes, which when fertilized with a pollen nucleus with 14 chromosomes, produces progeny plants with 2n = 40 chromosomes. The data also indicated that chromosome arm 7Dp probably contains a second gene that is capable of preventing the production of triploid plants. Key words: Triticum turgidum L. var. durum, polyploidy, aneuploid, triploid, monosomic.

Cytogenetic studies of aneuploids in rapeseed. II. Morphology, fertility, and cytology of self-pollinated progenies of monosomic plants of Brassica napus L.

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 174-179 ◽  
Author(s):  
Ru-ying Chang ◽  
William Tai ◽  
Z. Fan
Keyword(s):  
Brassica Napus ◽  
Key Words ◽  
Average Frequency ◽  
Dosage Effect ◽  
Brassica Napus L ◽  
Pollen Mother Cells ◽  
Cytogenetic Studies ◽  
Mode Of Transmission ◽  
Mother Cells ◽  
Multivalent Association

Cytogenic studies were conducted on self-pollinated progenies from two monosomic lines of Brassica napus to ascertain the mode of transmission of the monosomic chromosome. An approximately 1:1 ratio of disomic to monosomic plants was obtained. Only one nullisomic plant was found among a total of 71 plants analyzed. The 1:1 ratio and the anaphase I disjunction (19–18) suggest that the gametes (n) were twice as competitive or functional as their counterpart (n − 1). Since quadrivalents were observed in the disomic plants and only trivalents in the monosomics, the monosomic chromosomes were believed to be the ones that were involved in the formation of multivalents. The percentage of multivalent association in monosomic plants was almost double that in disomic plants. In the disomic plants, an average of 11.96% of pollen mother cells had one to two quadri-valents. The average frequency of trivalents in the monosomics was 23.63%. It was suggested that pairing of these homologs was genetically controlled with a dosage effect. The absence of one chromosome increased the frequency of multivalents. Key words: monosomic, Brassica, rapeseed, aneuploid.

Genetically controlled desynapsis in diploid Critesion violaceum and its hybrids with autotetraploid Psathyrostachys juncea

1984 ◽  
Vol 26 (5) ◽  
pp. 532-537 ◽  
Author(s):  
Richard R-C. Wang
Keyword(s):  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Intergeneric Hybrid ◽  
Dosage Effect ◽  
The Other ◽  
Pollen Mother Cells ◽  
Psathyrostachys Juncea ◽  
Self Pollination ◽  
Meiotic Irregularities ◽  
Mother Cells

Segregation for chiasma frequency was observed in the progeny of a diploid (2n = 14) Critesion violaceum strain following self-pollination. One S1 plant had normal metaphase pairing with an average of 0.43I + 6.78II, giving a high chiasma frequency, 12.03 per cell. The other S1 plant averaged 7.89I + 3.08II and a low chiasma frequency, 3.47 per cell. Examination of pollen mother cells at early prophases revealed that chromosome pairing was not totally prevented. It was concluded that desynapsis was responsible for the meiotic irregularities observed in the variant progeny. The same phenomena were observed in F1 hybrids of the cross between diploid C. violaceum and an induced autotetraploid (2n = 28), Psathyrostachys juncea. The normal F1 hybrid had a chiasma frequency of 12.81, but the desynaptic hybrid had a chiasma frequency of 6.94. A dosage effect of the desynaptic gene, which was probably recessive, was suggested. The implications and significance of this discovery are discussed.Key words: asynapsis, chiasma, meiosis, intergeneric hybrid.

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