SUPERNUMERARY CHROMOSOMES IN DIPLOID AND TETRAPLOID FORMS OF CRESTED WHEATGRASS

1962 ◽  
Vol 40 (4) ◽  
pp. 549-561 ◽  
Author(s):  
H. Baenziger
Keyword(s):  
Adventitious Roots ◽  
Average Frequency ◽  
Crested Wheatgrass ◽  
Pollen Mother Cells ◽  
Supernumerary Chromosomes ◽  
Reproductive Tissues ◽  
Primary Roots ◽  
Mother Cells

Supernumerary chromosomes were present in two diploid introductions of crested wheatgrass but absent in the diploid variety Fairway. In five tetraploid populations, they were present in 36.9 to 88.5% of the plants.Diploid plants contained supernumerary chromosomes in pollen mother cells, in primary roots, and in stem tissues, but not in adventitious roots. Supernumeraries in crested wheatgrass were usually smaller than basic chromosomes and they were not heterochromatic. There was good pairing between supernumeraries but not between supernumerary and A-chromosomes. Transmission of supernumeraries through the egg generally occurred in haploid numbers. In pollen, directed non-disjunction of supernumeraries towards the gametes took place with an average frequency of approximately 70%. The degree of transmission depended to some extent on the genotype of the parent and on the numbers of supernumeraries involved. Elimination of supernumeraries from reproductive tissues was generally low but became more pronounced at higher frequencies.

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.

In vivo karyotypic modifications following spontaneous cell fusion in maize (Zea mays L.)

1985 ◽  
Vol 27 (5) ◽  
pp. 580-585 ◽  
Author(s):  
John P. Peeters ◽  
A. J. F. Griffiths ◽  
Garrison Wilkes
Keyword(s):  
Zea Mays ◽  
Cell Fusion ◽  
Zea Mays L ◽  
Pollen Mother Cells ◽  
Supernumerary Chromosomes ◽  
Natural Mechanism ◽  
Mother Cells ◽  
Accessory Chromosomes ◽  
Cell Fusions

Spontaneous cell fusion has been detected during meiosis of pollen mother cells in a Himalayan popcorn called Sikkim Primitive. In postfusion meiotic cells one of the chromosome complements was often found to undergo modification producing a range of outcomes including aneuploidy and the formation of cells with modified supernumerary chromosomes. These abnormalities have been followed through three generations and new karyotypes containing modified supernumerary chromosomes were recovered in the F1 and F2 following the abnormal meiosis. These inherited additional chromosomes presumably arose from the cell fusions of the pollen mother cells and therefore our observations may indicate a natural mechanism for the formation of accessory chromosomes.Key words: spontaneous cell fusion, accessory chromosomes, Zea mays.

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.

Chromosome localization of genes that control synchronous development of pollen mother cells in wheat

Caryologia ◽  
2003 ◽  
Vol 56 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Wei Li ◽  
Jun Yang ◽  
You-Fu Pan ◽  
Guang-Qin Guo ◽  
Guo-Chang Zheng
Keyword(s):  
Chromosome Localization ◽  
Pollen Mother Cells ◽  
Synchronous Development ◽  
Mother Cells

An ultrastructural study of cytomixis in tobacco pollen mother cells

PROTOPLASMA ◽  
2011 ◽  
Vol 248 (4) ◽  
pp. 717-724 ◽  
Author(s):  
Sergey R. Mursalimov ◽  
Elena V. Deineko
Keyword(s):  
Ultrastructural Study ◽  
Pollen Mother Cells ◽  
Tobacco Pollen ◽  
Mother Cells

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.

TETRAPLOID TARAXACUM KOK-SAGHYZ: I. CHARACTERS OF THE LEAVES AND INFLORESCENCES IN THE PARENTAL COLCHICINE-INDUCED GENERATION

1945 ◽  
Vol 23c (4) ◽  
pp. 131-143 ◽  
Author(s):  
M. W. Bannan
Keyword(s):  
Guard Cells ◽  
Stages Of Development ◽  
Pollen Mother Cells ◽  
Mother Cells

Seedlings at different stages of development were treated with colchicine. Successive selections on the aspect of the seedlings soon after treatment, on size of the guard cells at the time of repotting, and finally, after overwintering, on counts of the chromosomes in the pollen mother cells yielded a few hundred plants with tetraploid crowns. These plants bore fewer, broader leaves and fewer, bigger inflorescences with larger achenes than did selected large-celled diploids given the same treatment, but in general the plants were no bigger. A few of the tetraploids were self-fertile (if not apomictic) early in the spring, but later all tested plants proved self-sterile.

CHROMOSOMAL ABERRATIONS IN A DIPLOID HAWORTHIA SUBFASIATA

1976 ◽  
Vol 18 (2) ◽  
pp. 281-286 ◽  
Author(s):  
C. C. Chinnappa ◽  
J. C. Semple
Keyword(s):  
Chromosomal Aberrations ◽  
Pollen Mother Cells ◽  
Mother Cells

In two diploid specimens of Haworthia subfasciata (2n = 14) several kinds of chromatid and subchromatid aberrations occurred. In some pollen mother cells E-type and U-type bridges were present. In other cells bridges and fragments were formed due to asymmetrical reunion of nonsister chromatids following breakage. A translocation involving the satellites of two L pair chromosomes was observed in one plant.

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