INTROGRESSION BETWEEN THE CULTIVATED HEXAPLOID OAT A. SATIVA AND THE TETRAPLOID WILD A. MAGNA AND A. MURPHYI

1977 ◽  
Vol 19 (1) ◽  
pp. 59-66 ◽  
Author(s):  
G. Ladizinsky ◽  
R. Fainstein
Keyword(s):  
Gene Transfer ◽  
Chromosome Number ◽  
Small Proportion ◽  
Parental Species ◽  
Hexaploid Species ◽  
Pentaploid Hybrid ◽  
Restoration Of Fertility

Introgression between the hexaploid (2n = 42) oat A. sativa and the newly discovered tetraploid (2n = 28) species A. magna and A. murphyi was studied by the rate of stabilization of chromosome number, restoration of fertility of pentaploid hybrid derivatives and the ultimate gene transfer between the tetraploid and the hexaploid levels. The complete self-sterility of the pentaploid F1 hybrids was overcome by massive back-pollination to the parental species. Great variation in chromosome number (12-48) was found among the viable F1 female gametes. Meiotically stable and reasonably fertile derivatives were selected only at the F2 of the BC and in a relatively small proportion. Gene transfer between the tetraploid and the hexaploid species was demonstrated by introducing the allele for nonshattering seed from the cultivated oat A. sativa to both A. magna and A. murphyi, and lemma hairiness from the tetraploids to the hexaploid level. The possible exploitation of introgression between the polyploid oats for breeding purposes has been pointed out and the potential of A. magna and A. murphyi as cultivated oats has been briefly discussed.

FURTHER STUDIES ON NATURAL SELECTION AMONG HYBRIDS OF CARDUUS ACANTHOIDES AND CARDUUS NUTANS

1964 ◽  
Vol 42 (12) ◽  
pp. 1605-1613 ◽  
Author(s):  
R. J. Moore ◽  
G. A. Mulligan
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Parental Species ◽  
Experimental Studies ◽  
Great Decrease ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Experimental Plots ◽  
Better Than ◽  
Made In

A third 5-year survey made in 1962 of Carduus acanthoides, C. nutans, and their hybrids in Grey Co., Ontario, revealed that a great decrease in these populations had occurred. C. acanthoides and hybrids similar to this species had survived better than C. nutans but very little spread of either species seemed to have occurred in 1957–1962. In experimental plots the hybrid has been made and backcrossed to the parental species. The species differ in chromosome number (C. acanthoides, 2n = 22; C. nutans, 2n = 16) and hybrids have intermediate numbers. Evidence was found from field and experimental studies that the progeny of the F1 hybrid included a greater proportion of seedlings with the higher chromosome numbers than with the lower and intermediate numbers. It is suggested that this selection may operate through the rejection of the longer chromosomes received from C. nutans, which, in certain zygotic combinations may constitute an excess of chromatin lethal to the zygote.

The bearing of Phoxinus (Cyprinidae) hybridity on the classification of its North American species

1970 ◽  
Vol 48 (6) ◽  
pp. 1167-1177 ◽  
Author(s):  
Pierre Legendre
Keyword(s):  
Chromosome Number ◽  
Discriminant Function ◽  
North American ◽  
Parental Species ◽  
North American Species ◽  
Discriminant Functions

Three populations of Phoxinus eos × P. neogaeus were found to form single Mendelian populations, by comparison with the parental species through a discriminant function. The hybrids of one of these populations were found to be fertile. A fourth hybrid collection, studied by three discriminant functions, was found to contain Semotilus margarita, P. eos × P. neogaeus, and hybrids of S. margarita with at least P. eos, but possibly P. eos × P. neogaeus. The presence of this hybrid, when related to the chromosome number of the species concerned, suggests the transfer of S. margarita to the genus Phoxinus.

A TAXONOMIC STUDY OF WESTERN CANADIAN SPECIES IN THE GENUS BETULA

1966 ◽  
Vol 44 (7) ◽  
pp. 929-1007 ◽  
Author(s):  
Janet R. Dugle
Keyword(s):  
Gene Flow ◽  
Chromosome Number ◽  
North American ◽  
Parental Species ◽  
Environmental Influence ◽  
Taxonomic Study ◽  
Environmental Selection ◽  
First Time ◽  
Lower Chromosome Number

Five western North American birches, Betula fontinalis, B. glandulosa, B. glandulifera, B. resinifera, and B. papyrifera, are studied taxonomically. Four hybrids, B. × winteri, B. × sargentii, B. × arbuscula, and B. × uliginosa, are described for the first time and three others, B. × utahensis, B. × eastwoodae, and B. × sandbergii, are also included. Populations formed when species are in contact have been analyzed and the nature of several hybrid entities determined. B. × uliginosa results from B. resinifera × B. glandulifera. In this population, introgression is toward B. glandulifera, which has the higher chromosome number. B. glandulifera also hybridizes with B. glandulosa producing B. × sargentii. Most gene flow is toward B. glandulifera, which has the higher chromosome number. In B. glandulosa × B. fontinalis (B. × eastwoodae) introgression was little influenced by environmental selection, the hybrid was as common as either parental species, and any gene flow was in either direction. B. × utahensis results from B. papyrifera × B. fontinalis. Introgression is toward B. papyrifera. Hybridization of B. × sargentii and B. papyrifera produces B. × arbuscula, a rare hybrid. Hybridization of B. resinifera and B. papyrifera results in B. × winteri, with introgression in both directions. B. × sandbergii results from B. papyrifera × B. glandulifera. Probably as a result of environmental influence in the analysis area, introgression was toward B. glandulifera, with the lower chromosome number.

Cytotaxonomic studies of Draba species of Canada and Alaska: D. ventosa, D. ruaxes, and D. paysonii

1971 ◽  
Vol 49 (8) ◽  
pp. 1455-1460 ◽  
Author(s):  
Gerald A. Mulligan
Keyword(s):  
North America ◽  
Chromosome Number ◽  
Related Species ◽  
Basic Chromosome Number ◽  
Base Number ◽  
Western North America ◽  
Closely Related Species ◽  
Basic Chromosome ◽  
Hexaploid Species

The cytotaxonomy of three closely related species of Draba, of the mountains of western North America, is discussed and a key is given: D. ventosa A. Gray (2n = 36), D. ruaxes Payson & St. John (2n = ca. 72), and D. paysonii Macbride (2n = 42). Evidence is presented demonstrating that D. ventosa and D. paysonii are triploids reproducing by agamospermy whereas the hexaploid species D. ruaxes is a sexual outcrosser. The former two species produce seed apomictically without any pollen stimulation. Draba ventosa and D. ruaxes have the basic chromosome number x = 12 and D. paysonii has the base number x = 14.

CYTOGENETIC STUDIES IN AMARANTHUS: II. NATURAL INTERSPECIFIC HYBRIDIZATION BETWEEN AMARANTHUS DUBIUS AND A. SPINOSUS

1959 ◽  
Vol 37 (5) ◽  
pp. 1063-1070 ◽  
Author(s):  
William F. Grant
Keyword(s):  
Chromosome Number ◽  
Parental Species ◽  
Diploid Species ◽  
Gene Exchange ◽  
Stomatal Size ◽  
Amaranthus Spinosus ◽  
Cytogenetic Studies ◽  
Mean Size ◽  
Pollen Grain Size ◽  
The Mean

Spontaneous triploid hybrids (2n = 49) were discovered between Amaranthus spinosus L. (2n = 34), a diploid species, and A. dubius Mart. ex Thellung (2n = 64) which was found to be a tetraploid. Meiosis in the hybrids was irregular and 15 univalents were most frequently found along with the bivalents pairing apparently allosyndetically (15 I's + 17 II's = 2n = 49) at metaphase I. Univalents were excluded from the telophase nuclei in both meiotic divisions resulting in supernumerary microspores and in a reduction in the mean size of the microspores. Consequently, the triploids were largely sterile and the few undersized seeds produced failed to germinate. Seed weight, seed volume, stomatal size, and pollen grain size were proportional to chromosome number in the parents only, not in their hybrids. Since A. dubius exhibits typical bivalent behavior in synapsis, it is considered to be an allotetraploid in which A. spinosus has been one progenitor. It is suggested that the diploid A. quitensis H. B. K. (2n = 32) might be the other progenitor, but from chromosome number relationships and morphological considerations more than two species may be involved. As a result of the high sterility of the triploids, gene exchange between the parental species must be of a very limited nature.

scholarly journals Fertility of Triploid Highbush Blueberry

1991 ◽  
Vol 116 (2) ◽  
pp. 336-341 ◽  
Author(s):  
N. Vorsa ◽  
James R. Ballington
Keyword(s):  
Gene Transfer ◽  
Chromosome Number ◽  
Chromosome Numbers ◽  
2N Gametes ◽  
Basic Chromosome Number ◽  
Highbush Blueberry ◽  
Pollen Stainability ◽  
Frequency Distributions ◽  
Basic Chromosome ◽  
2N Gamete

Eight highbush blueberry (V. corymbosum L.) triploids (2n = 3x = 36) were crossed with diploids (2n = 2x = 24), tetraploids (2n = 4x = 48), and hexaploids (2n = 6x = 72). No plants were recovered from 4021 3x × 2x crosses. One triploid was relatively fertile in 3x × 4x and 3x × 6x crosses, which is most likely attributable to 2n gamete production in the triploid. The lack of fertility of triploids, which do not produce 2n gametes, in crosses with diploids and tetraploids suggests that the production of gametes with numerically balanced (n = 12 or 24) chromosome numbers is extremely low. In addition, the inability to recover progeny from 3x × 2x crosses also suggests that aneuploid gametophytes and/or zygotes, including trisomics, are inviable in blueberry. Pollen stainability was also highly reduced in triploids. Frequency distributions of anaphase I pole chromosomal constitutions of three triploids were significantly different from one another. Two of the three distributions were shifted toward the basic chromosome number of 12, with one triploid having 25% poles with 12 chromosomes. However, the sterility of 3x × 2x and 2x × 3x crosses indicates that lagging chromosomes during meiotic anaphases are probably not excluded from gametes, resulting in unbalanced gametes in blueberry. Triploids can be used as a bridge to facilitate gene transfer from the diploid and tetraploid levels to the hexaploid level in blueberry.

ATTEMPTED GENE TRANSFER FROM TETRAPLOIDS TO DIPLOIDS IN TRITICUM

1981 ◽  
Vol 23 (4) ◽  
pp. 639-645 ◽  
Author(s):  
H. C. Sharma ◽  
J. G. Waines
Keyword(s):  
Gene Transfer ◽  
Chromosome Number ◽  
Seed Development ◽  
Seed Set ◽  
Triticum Turgidum ◽  
Seed Viability ◽  
Unreduced Gametes ◽  
Reciprocal Crosses ◽  
Advanced Backcross ◽  
Selection For

The possibility of introgression from tetraploid (2n = 28) AABB to diploid (2n = 14) AA wheats was investigated. Reciprocal crosses were made between tetraploid Triticum turgidum L. var. durum Desf. and diploids T. monococcum L. var. boeoticum Boiss., or T. urartu Tum.; and between T. turgidum var. carthlicum Nevski and T. monococcum L., or boeoticum, or urartu. The triploid F1 hybrids were backcrossed to diploid parents. All backcross derivatives were lethal at BC1 or BC2 except those of durum × boeoticum which were carried to BC4. However, neither fertile plants nor plants with the diploid chromosome number were obtained up to BC4 generation. As backcross generations advanced, backcross seed set, seed development, seed viability and plant vigor decreased. The failure of introgression from tetraploid to diploid wheats may be due to differential selection for unreduced gametes and adverse nucleo-cytoplasmic interactions.

ASYMMETRY OF CHROMOSOME NUMBER 1 PAIR IN THREE GENERATIONS OF A PHENOTYPICALLY NORMAL FAMILY

1968 ◽  
Vol 10 (3) ◽  
pp. 575-589 ◽  
Author(s):  
Kuang-Lin Ying ◽  
Elizabeth J. Ives
Keyword(s):  
Chromosome Number ◽  
Small Proportion ◽  
Normal Family ◽  
Marker Chromosome ◽  
Culture Technique ◽  
Crossing Over ◽  
Replication Pattern ◽  
Genetic Inactivation ◽  
Three Generations ◽  
Extended Region

A family is reported in which 6 of the 15 members studied carry a greatly lengthened #1 chromosome. This has segregated in three generations without phenotypic effect.Blood grouping provides evidence in favour of linkage of the Duffy locus and #1 chromosome.Autoradiographic studies demonstrate that DNA replication in the extended region of the marker chromosome occurs late in the majority of cells but early in a small proportion of cells in each of the three individuals thus studied. Possible explanations discussed include environmental modifications in culture technique, an unstable replication pattern in the extended region, and the chance that somatic crossing over of homologues allows a shift of a hypothetical "genetic inactivation centre" from one chromosome to the corresponding region of its homologue.

Frequency and possible consequences of hybridization between Schistosoma haematobium and S. mattheei in the Eastern Transvaal Lowveld

1990 ◽  
Vol 64 (4) ◽  
pp. 333-336 ◽  
Author(s):  
F. J. Kruger
Keyword(s):  
Mathematical Model ◽  
Small Proportion ◽  
Schistosoma Haematobium ◽  
Parental Species ◽  
Single Species ◽  
Human Infection

ABSTRACTA survey was conducted at a locality in the Eastern Transvaal Lowveld where the prevalence of human infection with the bovine parasite, Schistosoma mattheei, is relatively high. It was found that, when compared to the number of S. haematobium eggs released into the environment, the number of S. mattheei eggs, with enclosed hybrid miracidia, is small. The consequences of backcrossing between the hybrids and S. haematobium was considered; a mathematical model indicated that a high percentage of the S. haematobium population should contain a small proportion of S. mattheei genes. The results indicate that it is highly unlikely that the two species will evolve into a single species, neither does it seem that the virulence of the parental species will be influenced.

QUANTITATIVE VARIATION IN DNA AS RELATED TO PLOIDY LEVEL AND SPECIES IN SOME WILD ROSES

1972 ◽  
Vol 14 (2) ◽  
pp. 347-351 ◽  
Author(s):  
M. H. El-Lakany
Keyword(s):  
Chromosome Number ◽  
Ploidy Level ◽  
Dna Content ◽  
Diploid Species ◽  
Quantitative Variation ◽  
Chromosome Behaviour ◽  
Interspecific Relationships ◽  
Hexaploid Species ◽  
Dna Contents ◽  
Relative Dna Content

Relative DNA content and chromosome number and behaviour were studied in Manitoba wild roses. The hexaploid, Rosa acicularis, contained the largest amount of DNA, about three times that of the diploid, R. woodsii. Another diploid species, R. blanda, contained less DNA than R. woodsii. One specimen, identified as R. blanda with some introgression from R. woodsii, had the same amount of DNA as the latter species. R. × dulcissima, a hybrid between R. blanda and R. woodsii, had DNA contents similar to R. woodsii. The origin of a tetraploid, with DNA contents intermediate between diploid and hexaploid species, and 14 bivalents in diakinesis, was suggested to be hybridization between R. acicularis and a diploid rose. Chromosome behaviour in meiosis and DNA content were used in a discussion of interspecific relationships.

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