CYTOGENETIC STUDIES IN AMARANTHUS: I. CYTOLOGICAL ASPECTS OF SEX DETERMINATION IN DIOECIOUS SPECIES

1959 ◽  
Vol 37 (3) ◽  
pp. 413-417 ◽  
Author(s):  
William F. Grant
Keyword(s):  
Chromosome Number ◽  
Sex Determination ◽  
Chromosome Numbers ◽  
Somatic Chromosome ◽  
Pollen Grain ◽  
Somatic Chromosome Number ◽  
Dioecious Species ◽  
Absolute Size ◽  
Morphological Studies ◽  
Cytogenetic Studies

Cytological observations are contained in this report on four dioecious species of Amaranthns, two of which were formerly included in the genus Acnida. The species studied are A. arenicola, A. palmeri, A. tamariscinus, and A. tuberculatus. Three of these species have a diploid chromosome number of 32, whereas A. palmeri has a somatic chromosome number of 34. A single spontaneous triploid (2n = 48) female plant was found in collections of A. tamariscinus and a tetraploid (2n = 64) male plant in collections of A. tuberculatus. A fifth species, A. australis, has previously been reported as having 32 somatic chromosomes. The chromosome numbers for half the dioecious species of Amaranthus have now been determined. Detailed observations on the dividing chromosomes of these species in mitosis, in meiosis, and in the first division of the nucleus in the pollen grain have been made and have failed to distinguish heteromorphic chromosomes which might be associated with sex determination. The small size of the chromosomes has made detailed morphological studies impractical and there is no marked difference in absolute size of the chromosomes between species. Since haploid numbers of 16 and 17 are found in both monoecious and dioecious species, it would seem that the aneuploid condition in Amaranthus arose early and hybridization within the genus has resulted in promoting the genie condition which has been necessary for the expression of the dioecious condition.

STUDIES ON THE CYTOLOGY OF BROMEGRASS, BROMUS INERMIS LEYSS.

1958 ◽  
Vol 38 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Björn Sigurbjörnsson ◽  
Akira Mochizuki ◽  
John D. Truscott
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Somatic Chromosome ◽  
Seed Set ◽  
Bromus Inermis ◽  
Somatic Chromosome Number ◽  
Simultaneous Selection ◽  
Selection For ◽  
Type Strains ◽  
Selection Of

A population of 222 plants of 16 varieties and strains of northern and southern bromegrass was studied for somatic chromosome number. The following observations were noted: Aneuploid plants, including the chromosome numbers 54, 55, 57 and 58, were found within the species, Bromus inermis. One plant was found to have 49 chromosomes. A cytological difference was found between certain varieties of northern and southern types of bromegrass. The northern type had a significantly higher number of aneuploid plants with chromosome numbers in excess of 56, while the southern type had more aneuploid plants with fewer than 56 chromosomes. Some evidence was found suggesting that selection of northern type strains may bring about a simultaneous selection for additional chromosomes, whereas selection for southern type strains may involve a simultaneous selection for plants with missing chromosomes. Average seed set was found to be lowered in the presence of two additional chromosomes or absence of two chromosomes from the euploid complement.

scholarly journals Interphase nuclear phenotype and chromosomal variation in Cynodon dactylon (L.) pers

2019 ◽  
Vol 27 ◽  
pp. 133-141
Author(s):  
SK Nitu ◽  
SMS Islam ◽  
H Tarique
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Somatic Chromosome ◽  
Cynodon Dactylon ◽  
Nuclear Organization ◽  
Nuclear Volume ◽  
Chromosomal Variation ◽  
Nuclear Area ◽  
Somatic Chromosome Number ◽  
Interphase Chromosome

Interphase nuclear phenotype in different accessions (Acc.) of Cynodon dactylon studied in the present experiment showed chromocentric nuclear organization and the chromocenters were found to be visible clearly. The chromocenter numbers were not same and sometimes it was found to be significantly less and never more than total number of chromosomes. Percentages of heterochromatin values were expressed per nuclear area and the values range from 19.759% (Acc. 16) to 66.022% (Acc.18). Nuclear volume as well as interphase chromosome volume was found to vary 0.674 μm3 (Acc.6) to 41.921 μm3 (Acc.10) and from 0.028 μm3 (Acc. 6) to 1.905 μm3 (Acc. 10), respectively. The somatic chromosome number found to vary from 12 to 40. 2n = 18 chromosomes were found in eight accessions of C. dactylon. Only one accession was found to be tetraploid and rest of them aneuploid whose chromosome numbers were 12, 14, 16, 22, 24, 26, 32, 40 etc. The availability of aneuploid shows great aspects of forage breeding programme. J. bio-sci. 27: 133-141, 2019

A CYTOLOGICAL STUDY OF THE GENUS POA L.

1937 ◽  
Vol 15c (6) ◽  
pp. 281-297 ◽  
Author(s):  
J. M. Armstrong
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
High Frequency ◽  
Somatic Chromosome ◽  
Poa Pratensis ◽  
Basic Chromosome Number ◽  
Somatic Chromosome Number ◽  
Indigenous Plants ◽  
Somatic Chromosome Numbers ◽  
Fibre Attachment

The somatic chromosome numbers of 20 species of Poa were determined. The basic chromosome number for the genus was found to be seven. The species arranged themselves in a polyploid series from diploid to dodecaploid, tetraploids and hexaploids being the most numerous. Three aneuploid species possessed chromosome numbers suggestive of a nonaploid origin. Polymorphism was found to be present in P. compressa L., P. palustris L. and P. nemoralis L. All species examined conformed to the long chromosome type common to the subfamily, Pooideae. The spindle fibre attachment for the chromosomes in the various species ideograms was found to be regularly median or submedian.The chromosome variability and the mode of seed production were examined in Poa pratensis L., using selected, uniform strains, indigenous plants and plants grown from commercial seed. The somatic chromosome number was found to range from 50 to 87 ± 1, 10 of the 19 plants examined possessing aneuploid numbers. The selected strains possessed the same chromosome number for both plants examined, while in the other material the number was variable. A study of meiosis in the P.M.C. showed the selected strains to vary from regular behavior to an irregularity of 3.9 unpaired univalents per cell. All strains possessed large percentages of morphologically good pollen which germinated actively on the stigmas. Reduction was observed in the E.M.C. of the selected strains and a study of the course of embryological development showed no irregularities which might lead to aposporous reproduction. A high frequency of polyembryony was observed which was correlated to the degree of irregularity at meiosis. A theory is advanced to explain how constant aneuploid numbers may be maintained in sexually reproduced strains.

Cytology of Betula alba L. complex

1984 ◽  
Vol 85 (1-2) ◽  
pp. 49-64 ◽  
Author(s):  
I. R. Brown ◽  
D. A. Williams
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Somatic Chromosome ◽  
Hybrid Origin ◽  
General Situation ◽  
Somatic Chromosome Number ◽  
Chromosome Counts ◽  
Paper Briefly ◽  
Leaf Tissues ◽  
Taxonomic Confusion

SynopsisThe morphological variation between and within species of Betula has resulted in taxonomic confusion which chromosome studies have been aimed at reducing. The paper briefly reviews the general situation and summarizes recent work at Aberdeen.Betula forms a polyploid series with chromosome numbers ranging from 2n = 28 to 2n = 84. The native British arborescent birches B. pendula and B. pubescens Ehrh. have respectively 2n = 28 and 2n = 56 chromosomes. Meiosis is essentially regular but many phenomena occur which may account for the production of gametes with non-haploid chromosome numbers. Variation in somatic chromosome number within the leaf tissues of both species is common and trees have been identified whose modal chromosome counts lie between 28 and 56. Some of these trees are of hybrid origin while others may aneuploid B. pubescens. The former types are sterile while the latter cross freely amongst themselves and with 2n = 28 and 2n=56 trees.

Chromosome morphology of Clematis, subsection Viornae (Ranunculaceae)

1976 ◽  
Vol 54 (10) ◽  
pp. 1135-1139 ◽  
Author(s):  
W. Michael Dennis
Keyword(s):  
Chromosome Number ◽  
Somatic Chromosome ◽  
Chromosome Complement ◽  
Chromosome Morphology ◽  
Terminal Region ◽  
Somatic Chromosome Number ◽  
Median Region ◽  
Acrocentric Chromosomes ◽  
Subterminal Region ◽  
Marked Stability

Cytological studies were made on the following taxa: C. addisonii, C. filifera, C. glaucophylla, C. pitcheri, C. reticulata, C. texensis, C. versicolor, and C. viorna. All species were found to have a somatic chromosome number of 16 with a uniform karyotype consisting of five pairs of metacentric chromosomes with centromeres in the median region and three pairs of acrocentric chromosomes, two pairs with centromeres in the terminal region and one pair with centromeres in the subterminal region. These findings agree with reports of chromosome number and karyotype for other species of Clematis and suggest a marked stability of chromosome complement in the genus.

Investigations of the inheritance of flower variegation in Mirabilis jalapa L. 3. Somatic chromosome number, 4. Distribution of the pigments and 5. Chromatographic studies

Euphytica ◽  
1975 ◽  
Vol 24 (1) ◽  
pp. 6-12 ◽  
Author(s):  
W. N. M. Van Kester ◽  
C. J. T. Spitters ◽  
L. Vosselman ◽  
J. M. M. Engels ◽  
A. C. Zeven
Keyword(s):  
Chromosome Number ◽  
Somatic Chromosome ◽  
Somatic Chromosome Number ◽  
Mirabilis Jalapa

scholarly journals New Contribution to the Knowledge on the Chromosome Numbers of Turkish Cerambycidae (Coleoptera)

2021 ◽  
Vol 69 (2) ◽  
pp. 93-99
Author(s):  
Yavuz Koçak ◽  
Elmas Yağmur
Keyword(s):  
Chromosome Number ◽  
Sex Determination ◽  
Chromosome Numbers ◽  
Chromosome Count ◽  
Chromosomal Number ◽  
The Poor ◽  
Karyological Data ◽  
First Time

Information on the karyotypes of Turkish species of Cerambycidae is scanty. Our study contributes to the knowledge of the karyological data (chromosomal number and mechanism of sex determination) of five Turkish longicorn beetles; karyotypes of four taxa, one endemic, are described for the first time and for the remaining one, Purpuricenus budensis (Götz, 1783), the previously published chromosome count is confirmed. The chromosome number of Purpuricenus desfontainii inhumeralis Pic, 1891 and Purpuricenus budensis (Götz, 1783) (Cerambycinae, Trachyderini) was found to be 2n = 28 (13 + Xyp); Clytus rhamni Germar, 1817 and Plagionotus floralis (Pallas, 1773) (Cerambycinae, Clytini) 2n = 20 (9 + Xyp); and the endemic Dorcadion triste phrygicum Peks, 1993 (Lamiinae, Dorcadionini) 2n = 24 (11 + Xyp). In view of the paucity of data available until now, our study is important for both to improve the poor karyological knowledge of Turkish Cerambycidae and to provide an incentive for other researchers.

Chromosome studies on African plants. 9. Chromosome numbers in Ehrharta (Poaceae: Ehrharteae)

Bothalia ◽  
1989 ◽  
Vol 19 (1) ◽  
pp. 125-132 ◽  
Author(s):  
J. J. Spies ◽  
E. J. L. Saayman ◽  
S. P. Voges ◽  
G. Davidse
Keyword(s):  
Chromosome Number ◽  
Ploidy Level ◽  
Chromosome Numbers ◽  
Basic Chromosome Number ◽  
B Chromosomes ◽  
Basic Chromosome ◽  
Cytogenetic Studies ◽  
African Plants ◽  
First Time

Cytogenetic studies of 53 specimens of 14 species of the genus  Ehrharta Thunb. confirmed a basic chromosome number of 12 for the genus. Chromosome numbers for 13 species are described for the first time. The highest ploidy level yet observed in the genus (2n = lOx = 120) is reported for E. villosa var.  villosa. B chromosomes were observed in several specimens of four different species.

A new species of Trigonella sect. Ellipticae (Leguminosae-Papilionoideae) from Iran, including cytogenetic and anatomical notes

Phytotaxa ◽  
2015 ◽  
Vol 202 (1) ◽  
pp. 26 ◽  
Author(s):  
Massoud Ranjbar ◽  
ZAHRA HAJMORADI
Keyword(s):  
New Species ◽  
Chromosome Number ◽  
Related Species ◽  
Somatic Chromosome ◽  
Base Number ◽  
Somatic Chromosome Number ◽  
Chromosome Counts ◽  
Closely Related Species ◽  
A New Species

A new species, Trigonella bakhtiarica, from the Iranian province Chahar Mahal Va Bakhtiari is described, illustrated and compared to its most closely related species, T. aphanoneura. Trigonella bakhtiarica has a longer corolla and differs in the shape, surface and size of its pods, which are taxonomically informative characters in Trigonella sect. Ellipticae. Chromosome counts and meiosis assays show that both species are diploid, and that their euploid plants possess a somatic chromosome number of 2n = 2x = 16, which is consistent with the predicted base number of x = 8.

Cytological studies of subterranean clover (Trifolium subterraneum L.)

1952 ◽  
Vol 3 (3) ◽  
pp. 300 ◽  
Author(s):  
JJ Yates ◽  
NH Brittan
Keyword(s):  
Chromosome Number ◽  
Somatic Chromosome ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
The Other ◽  
Vicia Sativa ◽  
Somatic Chromosome Number ◽  
Separate Species ◽  
Apparent Relationship ◽  
Isolated Species

Somatic chromosome number and morphology in certain strains of subterranean clover and in species of several other fairly closely related genera have been observed. Dwalganup, Yarloop, Mt. Barker, Wenigup, Burnerang, and Red Leaf strains have each 16 fairly small chromosomes, the chromosome complexes being similar to one another and to that obtained by Wexelsen (1928) for the species. Palestine and Israel strains have each 12 large chromosomes, bearing no apparent relationship to those of the other strains but being the same in number and of a similar order of size to those found in Vicia sativa. Chromosome number and morphology may explain the failure to obtain intervarietal crosses involving Palestine, but not the low percentage of successful crosses between other strains. It is suggested that perhaps Palestine and Israel may be more correctly classed as strains of a separate species and that, with regard to their origin, Wexelsen's idea of mutational changes in isolated species offers probably the best explanation.

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