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.

scholarly journals Cytological Analysis of a Clethra alnifolia `Hokie Pink' × C. pringlei Hybrid

HortScience ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 339-342
Author(s):  
Sandra M. Reed
Keyword(s):  
Chromosome Number ◽  
Cold Hardiness ◽  
Male Gamete ◽  
Cytological Analysis ◽  
Root Tips ◽  
Chromosome Counts ◽  
Pollen Mother Cells ◽  
Size And Shape ◽  
Mother Cells ◽  
Deciduous Shrub

Clethra alnifolia L., a native deciduous shrub cultivated as an ornamental, was recently hybridized with C. pringlei S. Wats. The purpose of this hybridization was to combine the cold hardiness and adaptability of C. alnifolia with the ornamental foliage of C. pringlei. While most of the C. alnifolia × C. pringlei hybrids more closely resembled C. alnifolia than the paternal species, a `Hokie Pink' × C. pringlei hybrid (NA71586) with foliage that flushes red like C. pringlei was recovered. The objectives of this study were to analyze cytologically the F1 and produce a F2 population from NA71586. Chromosome counts from root tips cells indicated that NA71586 has 32 chromosomes. Since the chromosome number of C. alnifolia is 2n = 32 and that of C. pringlei was found to be 2n = 16, NA71586 appears to have developed following fertilization of a C. alnifolia egg with an unreduced male gamete from C. pringlei. Both `Hokie Pink' and C. pringlei exhibited primarily bivalent pairing in pollen mother cells (PMCs). Over half of the PMCs from NA71586 contained 16 bivalents, indicating substantial homology within the C. alnifolia genome. It was theorized that C. alnifolia is either an autotetraploid that exhibits bivalent pairing or a segmental allotetraploid produced from hybridization of species with similar genomes. More than 700 F2 progeny were obtained from self-pollination of NA71586. Although many of the F2 progeny resembled NA71586, variation in foliage color, size and shape was apparent in the population.

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.

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.

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.

A trigeneric hybrid between Hordeum, Aegilops, and Secale

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 647-649 ◽  
Author(s):  
A. Cabrera ◽  
A. Martin
Keyword(s):  
Chromosome Number ◽  
Chromosome Pairing ◽  
Seed Set ◽  
Female Parent ◽  
Hybrid Plant ◽  
Male Parent ◽  
Cytological Analysis ◽  
Pollen Mother Cells ◽  
Mother Cells

A trigeneric hybrid between Hordeum, Aegilops, and Secale was synthesized. The female parent was a fertile amphiploid between H. chilense and A. squarrosa and the male parent was S. cereale. The hybrid plant had the expected chromosome number of 2n = 21. Cytological analysis of pollen mother cells revealed no chromosome pairing. Morphology of the HchDR hybrid plant was similar to that of the Aegilops. The hybrid was sterile and no seed set was observed even after colchicine treeatment.Key words: Hordeum, Aegilops, Secale, trigeneric hybrid, cytology.

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.

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