Chromosome pairing in triploid and tetraploid hybrids in Elytrigia (Triticeae; Poaceae)

1984 ◽  
Vol 26 (5) ◽  
pp. 519-522 ◽  
Author(s):  
Patrick E. McGuire
Keyword(s):  
Chromosome Pairing ◽  
Genome Analysis ◽  
Triploid Hybrid ◽  
Pollen Mother Cells ◽  
Tetraploid Hybrid ◽  
A Genome ◽  
Mother Cells ◽  
Metaphase I

Mean chromosome pairing of 5.14I + 1.28II (rod) + 3.86II (ring) + 1.47III + 0.11IV (open) + 0.11V was observed in pollen mother cells at metaphase I in the triploid hybrid Elytrigia scirpea (K. Presl) Holub, 2n = 4x = 28 × E. bessarabica (Savul. et Rayss) Dubrovik, 2n = 4x = 14. Mean chromosome pairing of 3.71I + 2.29II (rod) + 1.82II (ring) + 2.64III + 0.29IV (open) was observed in the triploid hybrid E. curvifolia (Lange) Holub, 2n = 4x = 28 × E. bessarabica. Mean chromosome pairing of 3.00I + 0.93II (rod) + 1.57II (ring) + 1.36III + 1.79IV (open) + 1.I4IV (closed) + 0.79V was observed in the tetraploid hybrid E. junceiformis Löve et Löve, 2n = 4x = 28 × E. curvifolia. The first hybrid provides the first evidence by genome analysis that E. bessarabica possesses a genome (designated Eb) which is closely related to the genomes of E. scirpea (ES and ESC) and hence to the E genome of E. elongata (Host) Nevski, 2n = 2x = 14. The second and third hybrids provide the first evidence that the two genomes of E. curvifolia (designated EC and ECU) are related to the Eb genome of E. bessarabica and thus to the E genome of E. elongata.Key words: Elytrigia, homoeology, Triticum, phylogeny, triploid, tetraploid.

scholarly journals Homoeologous chromosome pairing at metaphase I of meiosis in Hordeum vulgare L. × H. bulbosum L. triploid hybrids (HvHbHb)

2020 ◽  
Vol 3 (2) ◽  
pp. 6-15
Author(s):  
G. I. Pendinen ◽  
M. Scholz
Keyword(s):  
Chromosome Pairing ◽  
Parental Species ◽  
Homoeologous Pairing ◽  
Hybrid Plants ◽  
Homoeologous Chromosome Pairing ◽  
A Genome ◽  
Cultivated Barley ◽  
Gish And Fish ◽  
Mother Cells ◽  
Metaphase I

Background. One of the ways to use the genetic potential of bulbous barley, which is characterized by a number of valuable traits, is interspecific hybridization. In crosses of H. vulgare (2x) × H. bulbosum (2x) and H. vulgare (4x) × H. bulbosum (4x) with a genome ratio of 1Hv: 1Hb in a hybrid embryo, elimination of bulbous barley chromosomes is observed in many cases, and the intensity of the process and the result of the crossing depend on the genotypes of the parental forms. This limits the possibility of including a significant variety of parental forms in crosses. Сrossing of diploid forms of H. vulgare with tetraploid accessions of H. bulbosum (4x) results in the formation of triploid hybrids (HvHbHb) with stable chromosomal composition in pollen mother cells (PMCs) at metaphase I (MI) of meiosis. These triploid hybrids can serve as a basis for obtaining series of introgressive lines of cultivated barley. One of the tasks of this type of work is to estimate the involvement of various chromosomes and their arms in homoeologous associations. The aim of this work was to study the possibility of homoeologous pairing of chromosomes of parental species at MI of meiosis in triploid hybrids using GISH and FISH with chromosome-specific markers, as well as to register the participation of individual arms of the cultivated barley chromosomes in homoeologous associations with the chromosomes of bulbous barley in triploid hybrids (HvHbHb).Materials and methods. Seven triploid hybrids of H. vulgare × H.bulbosum (HvHbHb) obtained in four combinations of crosses with the participation of three diploid cultivars of cultivated barley and two tetraploid accession of bulbous barley were used in this study. The features of homoeologous pairing of chromosomes at MI were studied using the method of fluorescent in situ hybridization (GISH and FISH) with chromosome-specific markers.Results All the studied hybrid plants are characterized by a stable chromosomal composition in PMCs at the MI stage of meiosis. Meiotic configurations formed by homoeologous chromosomes of the parental species, ranging from 0.87 to 1.40 on average per cell, were identified in all the studied plants. Among them, vbb trivalents prevailed. Analysis of chromosome pairing at MI in triploid hybrids revealed the participation of all chromosome arms of H. vulgare in homoeologous Hv-Hb associations, except for the short arm of chromosome 1H. In all the studied triploid hybrids, there is a tendency for a higher frequency of involvement of the long arms of chromosomes in the formation of homoeologous associations; this feature is most clearly manifested in case of chromosome 5H.Conclusions Intergenomic associations with the participation of all arms of H. vulgare chromosomes, except for the short arm of chromosome 1H, were revealed at MI in H. vulgare × H. bulbosum triploid hybrids (HvHbHb). Chromosome 5H, as well as any other cultivated barley chromosome, is characterized by a higher involvement of its long arm in homoeologous associations Hv-Hb, as compared to the short arm.

CHROMOSOME PAIRING IN TWO INTERSPECIFIC HYBRIDS OF TRIFOLIUM

1970 ◽  
Vol 12 (4) ◽  
pp. 790-794 ◽  
Author(s):  
Chi-Chang Chen ◽  
Pryce B. Gibson
Keyword(s):  
Phylogenetic Relationship ◽  
Chromosome Pairing ◽  
Trifolium Repens ◽  
Interspecific Hybrids ◽  
Triploid Hybrid ◽  
Close Phylogenetic Relationship ◽  
Metaphase I

Both Trifolium repens (2n = 32) and T. nigrescens (2n = 16) formed bivalents during meiosis. However, their triploid hybrid showed an average of 4.27 trivalents per microsporocyte at metaphase I. The frequency of trivalents in the hybrid between T. nigrescens and autotetraploid T. occidentale (2n = 32) was 5.69. The data are interpreted to indicate: (1) a possible autotetraploid origin of T. repens; and (2) a close phylogenetic relationship among T. repens, T. nigrescens and T. occidentale.

scholarly journals Meiosis in Oenothera missouriensis

1933 ◽  
Vol 113 (780) ◽  
pp. 57-70 ◽  
Keyword(s):  
Chromosome Pairing ◽  
Cytological Study ◽  
Stage Ii ◽  
Species Hybrid ◽  
Final Solution ◽  
Pollen Mother Cells ◽  
Closed Circle ◽  
Somatic Number ◽  
Mother Cells ◽  
Species Hybrids

A cytological study of the meiotic phenomena in Oenothera may not need an excuse in spite of the exhaustive studies of the genus made by numerous competent cytologists of this century. Up to the present time, all the investigators of Oenothera cytology have been successful in establishing that the basic ( n ) number of chromosomes in this genus is 7; although tetraploid (Gates, 1911), triploid (Cathcheside, 1931), and trisomic numbers might occur either naturally (by mutation) or could be produced by experiment. It is also known that the somatic number of chromosomes corresponds with the number of chromosome bodies in the diakinesis and metaphase of the heterotypic division.. Thus in diploid Oenothera species, hybrid, or mutant at the diakinesis of pollen mother cells 14 chromosomes have been shown to exist, withouth any doubt, in the configuration of a closed circle, in 7 ring pairs, or a mixtrue of free pairs and closed circles. Mathematically, there are 15 possible configurations in which 14 chromosomes can arrange themselves in the form of closed circle, ring pairs, or a combination of ring pairs and closed circles (Cleland and Blakeslee, 1931; Darlington, 1931). Of these 15 Possible configurations 13 have already been reported in various Oenothera species, hybrids and mutants (Darlington, 1931). Regarding the origin and significance of these chromosome configurations invsestigators have not yet reached an agreed opinion. Apart from the genetical significance, the much disputed cytological question of parasynaptic and telosynaptic methods of chromosome pairing is yet far from a final solution. In oenothera both the methods of pairing have strong sup-porters in consideration of observed cytological facts. The fact are (i) the continuous spireme (in leptotene stage); (ii) the pachynema and the diakinesis consisting of the 14 chromosomes arranged end to end. This arragement, known as catenation of chromosomes, favours the telosynaptic rather than the parasynaptic union. Wheras (i) double threads at the prophase, (ii) the looping of the threads, and (iii) the half number of bodies (7 ring pairs) at the diakinesis support the parasynaptic method of pairing of chromosomes. The occurence of a complete catenation of 14 chromosomes in some Oenotheras and the presence of 7 free pairs in others naturally suggests the question-whether they can be correlated with the two methods of chromosome-pairing in the meiosis of Oenothera .

Genome constitution of the Australian hexaploid grass Elymus scabrus (Poaceae: Triticeae)

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 147-151 ◽  
Author(s):  
J. Torabinejad ◽  
R. J. Mueller
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Intergeneric Hybrid ◽  
Meiotic Pairing ◽  
Genome Constitution ◽  
Psathyrostachys Juncea ◽  
Hybrid Plants ◽  
Thinopyrum Bessarabicum ◽  
Mother Cells ◽  
Metaphase I

Eight intergeneric hybrid plants were obtained between Elymus scabrus (2n = 6x = 42, SSYY??) and Australopyrum pectinatum ssp. retrofractum (2n = 2x = 14, WW). The hybrids were vegetatively vigorous but reproductively sterile. Examination of pollen mother cells at metaphase I revealed an average of 16.63 I, 5.29 II, 0.19 III, and 0.05 IV per cell for the eight hybrids. The average chiasma frequency of 6.77 per cell in the above hybrids strongly supports the presence of a W genome from A. pectinatum ssp. retrofractum in E. scabrus. Meiotic pairing data of some other interspecific hybrids suggest the existence of the SY genomes in E. scabrus. Therefore, the genome constitution of E. scabrus should be written as SSYYWW. Two other hybrid plants resulted from Elymus yezoensis (2n = 4x = 28, SSYY) crosses with A. pectinatum ssp. pectinatum (2n = 2x = 14, WW). Both were weak and sterile. An average of 0.45 bivalents per cell were observed at metaphase I. This clearly indicates a lack of pairing between W genome of Australopyrum and S or Y genomes of E. yezoensis. In addition, six hybrid plants of E. scabrus with Psathyrostachys juncea (2n = 2x = 14, NN) and one with Thinopyrum bessarabicum (2n = 2x = 14, JJ) were also obtained. The average bivalents per cell formed in both combinations were 2.84 and 0.70, respectively. The results of the latter two combinations showed that there is no N or J genome in E. scabrus.Key words: wide hybridization, chromosome pairing, genome analysis, Australopyrum, Elymus.

The three-dimensional arrangement of chromosomes at meiotic metaphase I in normal and interchange heterozygotes of Briza humilis

1990 ◽  
Vol 97 (3) ◽  
pp. 565-570
Author(s):  
JANET M. MOSS ◽  
BRIAN G. MURRAY
Keyword(s):  
Mother Cell ◽  
Three Dimensional ◽  
Meiotic Metaphase ◽  
Central Position ◽  
Normal Plant ◽  
Serial Sections ◽  
Pollen Mother Cells ◽  
Sector Analysis ◽  
Mother Cells ◽  
Metaphase I

Pollen mother cells at metaphase I have been reconstructed from serial sections in normal and interchange heterozygotes of Briza humilis. The pollen mother cells have an irregular shape with a prominent projection from the tangential face into the anther loculus. The seven bivalents of the normal plant are usually arranged with one bivalent in a central position surrounded by a ring of the remaining six or as a ring of all seven bivalents. The central:peripheral distribution of quadrivalents is different in two different interchange plants; in a sector analysis, where cells are divided into four quarters relative to the tangential face of the pollen mother cell, the two plants also show differences in quadrivalent distribution, indicating that individual chromosomes occupy different positions in the cell. The relevance of these results to the positioning of quadrivalents in lateral squashes of meiotic metaphase I are discussed.

Interlocked bivalents in reconstructed metaphase I cells of bread wheat

1985 ◽  
Vol 75 (1) ◽  
pp. 85-92
Author(s):  
J.S. Heslop-Harrison ◽  
M.D. Bennett
Keyword(s):  
Triticum Aestivum ◽  
Light Microscopy ◽  
Bread Wheat ◽  
Chromosome Pairing ◽  
Light Microscope ◽  
Serial Sections ◽  
Ring Bivalents ◽  
Mother Cells ◽  
I Cells ◽  
Metaphase I

Complete reconstructions of all the bivalents were made from electron micrographs of serial sections through six pollen mother cells at metaphase I of meiosis in Triticum aestivum (hexaploid bread wheat). At least two of these metaphases contained interlocked pairs of bivalents. In one, two ring bivalents were interlocked, while in another a rod bivalent ran through the centre of a ring bivalent. Two other groups of bivalents were too closely appressed to allow separation into individual bivalents and may have contained interlocks. Meiosis in other anthers of the same plants examined by light microscopy was considered normal. The frequency of interlocking found was much higher than reported from light-microscope spreads. Not all interlocks in metaphase I cells need adversely affect meiosis, but knowledge of their regularity and form may facilitate understanding the processes of chromosome pairing.

The Effect of Spindle Inhibitors Applied before Meiosis on Meiotic Chromosome Pairing

1973 ◽  
Vol 12 (1) ◽  
pp. 143-161 ◽  
Author(s):  
G. A. DOVER ◽  
R. RILEY
Keyword(s):  
Chromosome Pairing ◽  
Chloral Hydrate ◽  
Control Mechanism ◽  
Meiotic Chromosome ◽  
Chiasma Formation ◽  
Meiotic Pairing ◽  
Mitotic Spindles ◽  
Pollen Mother Cells ◽  
Meiotic Chromosome Pairing ◽  
Mother Cells

Injection of 0.5% colchicine into immature tillers of genotypes of Triticum aestivum, T. aestivum x Aegilops mutica and T. aestivum x Secale cereale hybrids induces asynapsis at first meiotic metaphase irrespective of the homologous or homoeologous nature of the potential pairing chromosomes. The induction of asynapsis occurs at a time during and immediately following the last premeiotic mitosis of pollen mother cells. No disruption of synapsis and chiasma formation occurs in anthers having pollen mother cells originally at leptotene or immediately prior to leptotene when cultured in White's medium plus colchicine. Tetraploid and octaploid pollen mother cells resulting from the disruption of premeiotic spindles by colchicine show pairing of chromosomes only in bivalents, in genotypes normally having a degree of multivalent pairing configurations. The induction of multipolar mitotic spindles with 0.01% colchicine results in the development of pollen mother cell mosaics with different numbers of chromosomes. Such cells show high levels of chromosome pairing, including multivalents, in some genotypes that normally have very little chromosome pairing. The injection of 0.5% chloral hydrate during the last premeiotic mitosis of the archesporium causes no disturbances of meiotic pairing. The results are discussed with reference to the hypothesis that the control mechanism of meiotic chromosome pairing involves centromeric microtubules of the spindle (not affected by chloral hydrate) that are responsible for the positional adjustment, during the last mitotic anaphase, of potential pairing partners.

Meiosis in triploid Lolium. I. Synaptonemal complex formation and chromosome configurations at metaphase I in aneuploid autotriploid L. multiflorum

Genome ◽  
1994 ◽  
Vol 37 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Huw M. Thomas ◽  
Barry J. Thomas
Keyword(s):  
Complex Formation ◽  
Synaptonemal Complex ◽  
Lolium Multiflorum ◽  
Synaptonemal Complexes ◽  
Pollen Mother Cells ◽  
Partner Exchange ◽  
Synaptonemal Complex Formation ◽  
Mother Cells ◽  
Axial Element ◽  
Metaphase I

A spreading technique for synaptonemal complexes (SCs) was applied to pollen mother cells of two aneuploid genotypes of autotriploid Lolium multiflorum (2n = 3x + 1 = 22). In the earliest nuclei analyzed the axial elements are in six groups of 3 and one group of 4. Most groups have formed multivalents with from one to five pairing partner exchanges, but there are also groups that have formed bivalents and univalents. Some axial elements have formed triple associations, in one case for the length of the trivalent. Unsynapsed axial elements remain aligned with their homologous SCs into pachytene, but this alignment is abolished as these axes pair heterologously among themselves until the entire axial element complement is synapsed. At metaphase I most chromosomes are associated as trivalents and quadrivalents.Key words: Lolium, triploid, pairing partner exchange, chiasma, multivalent.

Low glucosinolate Brassica juncea breeding line revealed to be nullisomic

Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 738-741 ◽  
Author(s):  
B F Cheng ◽  
G Séguin-Swartz ◽  
D J Somers ◽  
G Rakow
Keyword(s):  
Brassica Juncea ◽  
Interspecific Cross ◽  
Meiotic Behaviour ◽  
Breeding Line ◽  
Pollen Mother Cells ◽  
Chromosomal Segregation ◽  
B Genome ◽  
Hybrid Plants ◽  
Mother Cells ◽  
Metaphase I

The low glucosinolate Brassica juncea breeding line 1058 was derived from a BC1F3 plant of an interspecific cross between high glucosinolate Indian B. juncea (genome AABB, 2n = 36) line 60143 and B. rapa (genome AA, 2n = 20) canola strain CZY. Line 60143 had 2n = 36 chromosomes (18 bivalents at metaphase I) and strain CZY had 2n = 20 chromosomes (10 bivalents). Line 1058 was nullisomic, with 2n - 2 = 34 chromosomes, with 17 bivalents formed at metaphase I and an even chromosomal segregation of 17:17 at anaphase I. In F1 hybrid plants of the cross 1058 × CZY, 98.3% of the pollen mother cells had 10 bivalents and seven univalents. This is evidence that plants of line 1058 are nullisomic, missing one pair of B-genome chromosomes.Key words: low glucosinolate mustard, meiotic behaviour, cytogenetics.

Genomic constitution of the allo-octoploid Elymus tenuis (Poaceae: Triticeae) of New Zealand

2010 ◽  
Vol 23 (5) ◽  
pp. 381 ◽  
Author(s):  
Hai-Qin Zhang ◽  
Xue Bai ◽  
Bao-Rong Lu ◽  
Henry E. Connor ◽  
Yong-Hong Zhou
Keyword(s):  
New Zealand ◽  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Genomic Constitution ◽  
Pollen Mother Cells ◽  
Mother Cells

Elymus tenuis (Buch.) Á.Löve et Connor is a perennial octoploid (2n = 56) wheatgrass endemic to New Zealand. To investigate its genomic constitution, four artificial interspecific hybrids between E. tenuis and E. enysii (2n = 4x = 28, HW), and E. solandri (2n = 6x = 42, StYW) and E. multiflorus (2n = 6x = 42, StYW) were studied cytologically. Meioses in pollen mother cells (PMCs) of the hybrids showed relatively high chromosome pairing, with an average of 13.50 in E. enysii × E. tenuis, 20.22 in E. solandri × E. tenuis, 19.62 in E. multiflorus × E. tenuis, and 20.00 in E. tenuis × E. multiflorus bivalents per cell, respectively. The results indicate that E. tenuis is an allo-octoploid species, with the new and unique genomic constitution StYHW. An autochthonous origin is proposed for it.

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