scholarly journals Aegilops × Secale hybrids: the production and cytology of diploid hybrids

1971 ◽  
Vol 17 (1) ◽  
pp. 17-31 ◽  
Author(s):  
B. N. Majisu ◽  
J. K. Jones
Keyword(s):  
Embryo Culture ◽  
Interspecific Hybrids ◽  
Diploid Species ◽  
Genetic Mechanism ◽  
Genetic Incompatibility ◽  
Homologous Chromosomes ◽  
Homoeologous Chromosomes

SUMMARYHybrids between four diploid species of Aegilops and species of Secale were obtained by using embryo culture. There was a marked incompatibility in the crosses between Secale species and each of the four species in Section Sitopsis of Aegilops and Ae. mutica. It is suggested that this genetic incompatibility with Secale species is an additional similarity between these species of Aegilops and the diploid species of Triticum.Most chromosomes of Aegilops (A) and Secale (S) are univalent during meta-anaphase of meiosis in these hybrids, but some appeared to associate and others to pair as apparently normal chiasmate bivalents. Analysis of non-chiasmate and chiasmate associations showed that the frequencies of autosyndetic (AA and SS) and allosyndetic (AS) associations fitted the 3AA: 7AS: 3SS ratio expected if association and pairing is at random. Any deviations from random involved a deficiency rather than an excess of Aegilops-Secale pairing. There is no evidence that the chromosomes of Secale are homologous with those of Ae. caudata, Ae. comosa and Ae. umbel-lulata, and it is suggested that the genome of Secale species does not show any homology with the genomes of the genera Aegilops. This does not preclude the presence of homologous segments. It is suggested that the possibility of random association of chromosomes should be considered when occasional pairing in interspecific hybrids is analysed, and that identification of chromosomes and recognition of chiasmata are required. The possibilities of chiasmata between non-homologous chromosomes, of a genetic mechanism in rye which suppresses the pairing of homoeologous chromosomes, and of other factors causing asynapsis and pseudo-synapsis between genetically similar chromosomes are discussed.

Chromosomal distribution of genes in diploid Elytrigia elongata that promote or suppress pairing of wheat homoeologous chromosomes

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Jan Dvořák
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Diploid Species ◽  
Triticum Aestivum L ◽  
Hordeum Bulbosum ◽  
Triticum Urartu ◽  
Substitution Lines ◽  
Chromosomal Distribution ◽  
Key Words Wheat ◽  
Homoeologous Chromosomes

Triticum aestivum L. lines with added or substituted chromosomes of Elytrigia elongata (Host) Nevski were hybridized with Hordeum bulbosum L. to obtain haploids and with Triticum urartu Thum. to obtain interspecific hybrids. Chromosome pairing at metaphase I was investigated in the resulting haploids and hybrids and the parental addition and substitution lines. Genes that promoted pairing of homologous or homoeologous chromosomes were found on chromosome arms 3ES, 3EL, 4ES, 5Ep, and chromosome 6E of E. elongata. Genes that suppressed pairing of homoeologous chromosomes were found on chromosome arms 4EL and 7Eq. It is concluded that genes promoting or suppressing pairing of homoeologous chromosomes are ubiquitous among diploid species. Key words: wheat, Triticum, wheatgrass, Elytrigia elongata, heterogenetic pairing, chromosome pairing, pairing promotion, pairing suppression.

Evidence for genetic suppression of heterogenetic chromosome pairing in polyploidy species of Solanum, sect. Petota

1983 ◽  
Vol 25 (5) ◽  
pp. 530-539 ◽  
Author(s):  
Jan Dvořák
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Diploid Species ◽  
Diploid Hybrid ◽  
Polyploid Species ◽  
Chromosome Differentiation ◽  
Genetic Suppression ◽  
Solanum Sect ◽  
Paradoxical Results

Data on chromosome pairing in haploids and interspecific hybrids of Solanum, sect. Petota reported in the literature were used to determine whether the diploidlike chromosome pairing that occurs in some of the polyploid species of the section is regulated by the genotype or brought about by some other mechanism. The following trends emerged from these data. Most of the polyploid × polyploid hybrids had high numbers of univalents, which seemed to indicate that the polyploid species were constructed from diverse genomes. Haploids, except for those derived from S. tuberosum, had incomplete chromosome pairing. All hybrids from diploid × diploid crosses had more or less regular chromosome pairing, which suggested that all investigated diploid species have the same genome. Likewise, hybrids from polyploid × diploid crosses had high levels of chromosome pairing. These paradoxical results are best explained if it is assumed that (i) the genotypes of most polyploid species, but not those of the diploid species, suppress heterogenetic pairing, (ii) that nonstructural chromosome differentiation is present among the genomes of both diploid and polyploid species, and (iii) the presence of the genome of a diploid species in a polyploid × diploid hybrid results in promotion of heterogenetic pairing. It is, therefore, concluded that heterogenetic pairing in most of the polyploid species is genetically suppressed.

Evidence for the presence of an intercontinental genome in the Australian hexaploid alliance of Hibiscus Sect. Furcaria

1980 ◽  
Vol 28 (3) ◽  
pp. 369 ◽  
Author(s):  
MY Menzel ◽  
DW Martin
Keyword(s):  
Sri Lanka ◽  
South America ◽  
Interspecific Hybrids ◽  
New World ◽  
Hawaiian Islands ◽  
Diploid Species ◽  
Australian Species ◽  
Data Support ◽  
North And South America ◽  
North And South

Genomes of the G group in Hibiscus sect. Furcaria have been found previously in one African diploid species and in various ailoploid combinations in Africa, India and Sri Lanka, North and South America and the Hawaiian Islands. Study of 11 interspecific hybrids between the Australian species H. heterophyllus and H. splendens and G-genome testers indicates that genomes somewhat related to the G group are present in the Australian allohexaploid alliance. These genomes are designated G′. Several of the intercontinental hybrids studied were weak, inviable or morphologically abnormal. The data support the interpretation that the genomes of the Australian alliance have diverged more from African and New World genomes than the latter two have from each other.

scholarly journals Polyploidy Induces Centromere Association

2000 ◽  
Vol 148 (2) ◽  
pp. 233-238 ◽  
Author(s):  
Enrique Martinez-Perez ◽  
Peter J. Shaw ◽  
Graham Moore
Keyword(s):  
Gene Expression ◽  
Meiotic Prophase ◽  
Diploid Species ◽  
Major Effect ◽  
Anther Development ◽  
Polyploid Species ◽  
Homologous Chromosomes ◽  
Gamete Formation ◽  
Affect Gene Expression ◽  
Segregation Of Chromosomes

Many species exhibit polyploidy. The presence of more than one diploid set of similar chromosomes in polyploids can affect the assortment of homologous chromosomes, resulting in unbalanced gametes. Therefore, a mechanism is required to ensure the correct assortment and segregation of chromosomes for gamete formation. Ploidy has been shown to affect gene expression. We present in this study an example of a major effect on a phenotype induced by ploidy within the Triticeae. We demonstrate that centromeres associate early during anther development in polyploid species. In contrast, centromeres in diploid species only associate at the onset of meiotic prophase. We propose that this mechanism provides a potential route by which chromosomes can start to be sorted before meiosis in polyploids. This explains previous reports indicating that meiotic prophase is shorter in polyploids than in their diploid progenitors. Even artificial polyploids exhibit this phenotype, suggesting that the mechanism must be present in diploids, but only expressed in the presence of more than one diploid set of chromosomes.

In-vitro Regeneration of Interspecific Hybrids in Eggplant Species via Seed and Embryo Culture

2020 ◽  
Vol 8 (3) ◽  
pp. 226-237
Author(s):  
Nusrat Tsemah Afful ◽  
Daniel Nyadanu ◽  
Richard Akromah ◽  
Harry Mensah Amoatey ◽  
Fuseini Mohammed ◽  
...  
Keyword(s):  
Embryo Culture ◽  
Interspecific Hybrids ◽  
In Vitro Regeneration

The relationship between some Eurasian and American species of Bromus section Pnigma as determined by the karyotypes of some F1 hybrids

1983 ◽  
Vol 61 (3) ◽  
pp. 700-707 ◽  
Author(s):  
K. C. Armstrong
Keyword(s):  
Embryo Culture ◽  
Interspecific Hybrids ◽  
F1 Hybrids ◽  
Chromosome Size ◽  
The Relationship ◽  
Eurasian Species

Interspecific hybrids were successfully produced, using embryo culture, between Eurasian and American species of Bromus section Pnigma. Cytological observations on satellite type and chromosome size suggest that the two Eurasian species B. benekenii (Lange) Trimen and B. ramosus Huds. are more closely related to the American species (B. ciliatus L., B. latiglumis Hitchc., B. pacificus Shear, and B. richardsonii Link) than to other Eurasian species. It is suggested that the section Pnigma may contain two distinct groups of species that can be separated on the basis of chromosome size.

scholarly journals Interspecific Hybrids of Lilium longiflorum and L.*formolongi with L. rubellum and L. japonicum through Embryo Culture.

1992 ◽  
Vol 60 (4) ◽  
pp. 997-1002 ◽  
Author(s):  
Keiichi Okazaki ◽  
Yuji Umada ◽  
Osamu Urashima ◽  
Joichi Kawada ◽  
Masaaki Kunishige ◽  
...  
Keyword(s):  
Embryo Culture ◽  
Interspecific Hybrids ◽  
Lilium Longiflorum

scholarly journals A separation-of-function ZIP4 wheat mutant allows crossover between related chromosomes and is meiotically stable

2021 ◽  
Author(s):  
Azahara C. Martín ◽  
Abdul Kader Alabdullah ◽  
Graham Moore
Keyword(s):  
Wheat Breeding ◽  
Wild Type ◽  
Grain Number ◽  
Homologous Chromosomes ◽  
Chromosome 5B ◽  
Correct Pairing ◽  
New Gene ◽  
Multiple Genomes ◽  
Mutant Lines ◽  
Homoeologous Chromosomes

ABSTRACTMany species, including most flowering plants, are polyploid, possessing multiple genomes. During polyploidisation, fertility is preserved via the evolution of mechanisms to control the behaviour of these multiple genomes during meiosis. On the polyploidisation of wheat, the major meiotic gene ZIP4 duplicated and diverged, with the resulting new gene TaZIP4-B2 being inserted into chromosome 5B. Previous studies showed that this TaZIP4-B2 promotes pairing and synapsis between wheat homologous chromosomes, whilst suppressing crossover between related (homoeologous) chromosomes. Moreover, in wheat, the presence of TaZIP4-B2 preserves up to 50% of grain number. The present study exploits a ‘separation-of-function’ wheat Tazip4-B2 mutant named zip4-ph1d, in which the Tazip4-B2 copy still promotes correct pairing and synapsis between homologues (resulting in the same pollen profile and fertility normally found in wild type wheat), but which also allows crossover between the related chromosomes in wheat haploids of this mutant. This suggests an improved utility for the new zip4-ph1d mutant line during wheat breeding exploitation, compared to the previously described CRISPR Tazip4-B2 and ph1 mutant lines. The results also reveal that loss of suppression of homoeologous crossover between wheat chromosomes does not in itself reduce wheat fertility when promotion of homologous pairing and synapsis by TaZIP4-B2 is preserved.

Studies on an embryonic lethal hybrid in Drosophila

Development ◽  
1967 ◽  
Vol 17 (2) ◽  
pp. 405-423
Author(s):  
Janice D. Kinsey
Keyword(s):  
X Chromosome ◽  
Interspecific Hybrids ◽  
Genetic Mechanism ◽  
Abnormal Development ◽  
Central Importance ◽  
Embryonic Lethal ◽  
Female Hybrid ◽  
Drosophila Montana ◽  
Lethal Hybrid ◽  
Nucleocytoplasmic Interactions

The problems of nucleocytoplasmic interactions are of central importance in development and genetics. Studies of such interactions may help elucidate the mechanisms of differentiation of cells receiving the same genetic complement. One approach to a study of nucleocytoplasmic interactions is by examination of the development of interspecific hybrids, particularly those in which either syngamy fails to occur, or an abnormal development is produced. These studies describe a lethal hybrid which occurs between Drosophila montana and D. texana. In 1944, Patterson & Griffen described a genetic mechanism which acts in the hybrid females produced by crossing D. montana females to D. texana males. In this cross, only male offspring were produced, so that there appeared to be some incompatibility between the D. montana ooplasm and the D. texana X-chromosome which acted to kill the female hybrid embryos before hatching.

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