The cytology of Lycopersicon somatic hybrids II. A detailed analysis of chromosome pairing at meiosis in pollen mother cells of somatic hybrids of Lycopersicon esculentum and Lycopersicon peruvianum

1992 ◽  
Vol 248 (1323) ◽  
pp. 255-259 ◽  
Keyword(s):  
Lycopersicon Esculentum ◽  
Detailed Analysis ◽  
Chromosome Pairing ◽  
Somatic Hybrids ◽  
Lycopersicon Peruvianum ◽  
Pollen Mother Cells ◽  
Mother Cells

Chromosome pairing and potential for intergeneric recombination in some hypotetraploid somatic hybrids of Lycopersicon esculentum (+) Solanum tuberosum

Genome ◽  
1993 ◽  
Vol 36 (6) ◽  
pp. 1032-1041 ◽  
Author(s):  
J. H. de Jong ◽  
A. M. A. Wolters ◽  
J. M. Kok ◽  
H. Verhaar ◽  
J. van Eden
Keyword(s):  
Solanum Tuberosum ◽  
Lycopersicon Esculentum ◽  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Somatic Hybrids ◽  
Cytogenetic Study ◽  
Unreduced Gametes ◽  
Root Tip ◽  
Prophase I ◽  
Metaphase I

Three somatic hybrids resulting from protoplast fusions of a diploid kanamycin-resistant line of tomato (Lycopersicon esculentum) and a dihaploid hygromycin-resistant transformant of a monohaploid potato (Solanum tuberosum) line were used for a cytogenetic study on chromosome pairing and meiotic recombination. Chromosome counts in root-tip meristem cells revealed two hypotetraploids with chromosome complements of 2n = 46 and one with 2n = 47. Electron microscope analyses of synaptonemal complex spreads of hypotonically burst protoplasts at mid prophase I showed abundant exchanges of pairing partners in multivalents involving as many as eight chromosomes. In the cells at late pachytene recombination nodules were found in multivalents on both sides of pairing partner exchanges, indicating recombination at both homologous and homoeologous sites. Light microscope observations of pollen mother cells at late diakinesis and metaphase I also revealed multivalents, though their occurrence in low frequencies betrays the reduction of multivalent number and complexity. Precocious separation of half bivalents at metaphase I and lagging of univalents at anaphase I were observed frequently. Bridges, which may result from an apparent inversion loop found in the synaptonemal complexes of a mid prophase I nucleus, were also quite common at anaphase I, though the expected accompanying fragments could be detected in only a few cells. Most striking were the high frequencies of first division restitution in preparations at metaphase II/anaphase II, giving rise to unreduced gametes. In spite of the expected high numbers of balanced haploid and diploid gametes, male fertility, as revealed by pollen staining, was found to be negligible.Key words: synaptonemal complex, recombination, chromosome pairing, somatic hybrid, Lycopersicon esculentum (+) Solanum tuberosum.

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 .

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.

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.

Selection and characterization of somatic hybrids between Lycopersicon esculentum and Lycopersicon peruvianum

Plant Science ◽  
1990 ◽  
Vol 70 (2) ◽  
pp. 197-208 ◽  
Author(s):  
J. Wijbrandi ◽  
W. Van Capelle ◽  
C.J. Hanhart ◽  
E.P. Van Loenen Martinet-Schuringa ◽  
M. Koornneef
Keyword(s):  
Lycopersicon Esculentum ◽  
Somatic Hybrids ◽  
Lycopersicon Peruvianum

Ultrastructure of meiotic pairing in B chromosomes of Crepis capillaris. I. One-B and two-B pollen mother cells

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 611-621 ◽  
Author(s):  
G. H. Jones ◽  
J. A. F. Whitehorn ◽  
S. M. Albini
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Complex Surface ◽  
B Chromosome ◽  
B Chromosomes ◽  
Meiotic Pairing ◽  
Pollen Mother Cells ◽  
Crepis Capillaris ◽  
Axis Length ◽  
Mother Cells

Chromosome pairing of a small metacentric B chromosome in Crepis capillaris has been studied by synaptonemal complex surface spreading of pollen mother cells containing either one or two B chromosomes. The B-chromosome axis, on average, represents about 8.7% of the axis length of the standard A-chromosome set, which is less than the corresponding values for DNA content (10.6%) and mitotic chromosome volume (13.6%). Single B chromosomes commonly undergo fold-back pairing to give a symmetrical hairpin loop, which supports earlier suggestions that this B chromosome is an isochromosome. Two B chromosomes may show interarm pairing, exclusively, or interchromosome pairing, exclusively, or combinations of the two. Near the centromeres pairing occurs preferentially between arms of the same chromosome, but chromosome ends show random association. Some B chromosomes show anomalous pairing configurations, which may reflect further orders of reverse repeats within arms or, alternatively, nonhomologous pairing. The period of B-chromosome pairing is confined almost exclusively to zygotene, when the standard A chromosomes are pairing, but within this period their pairing is delayed relative to the A set. Individual B chromosomes at zygotene contain from one to three separate synaptonemal complex segments. These are widely distributed within the chromosomes, mainly in distal and interstitial regions; pairing is delayed around the centromere.Key words: B chromosomes, isochromosomes, synaptonemal complex.

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.

Fertile asymmetric somatic hybrids between Lycopersicon esculentum Mill. and Lycopersicon peruvianum var. dentatum Dun.

1993 ◽  
Vol 236-236 (2-3) ◽  
pp. 427-432 ◽  
Author(s):  
Yakov I. Ratushnyak ◽  
Nickolai N. Cherep ◽  
Anna V. Zavgorodnyaya ◽  
Sergei A. Latypov ◽  
Irina V. Borozenko ◽  
...  
Keyword(s):  
Lycopersicon Esculentum ◽  
Somatic Hybrids ◽  
Lycopersicon Peruvianum ◽  
Asymmetric Somatic Hybrids ◽  
Lycopersicon Esculentum Mill
Sign in / Sign up

Export Citation Format

Share Document