Chromosome pairing and fertility in Spartina × caespitosa

1970 ◽  
Vol 48 (1) ◽  
pp. 183-188 ◽  
Author(s):  
C. J. Marchant
Keyword(s):  
Chromosome Pairing ◽  
Seed Set ◽  
Meiotic Pairing ◽  
Pollen Stainability ◽  
Breeding Behavior ◽  
High Pollen ◽  
Hybrid Nature ◽  
In The Wild

A detailed study of meiosis and breeding behavior of Spartina × caespitosa (A. A. Eaton) Fern, and a comparison with S. patens (Ait.) Muhl. and S. pectinata Link, its putative parents, has revealed regular meiotic pairing, relatively high pollen stainability, and a low seed set in the hybrid when intercrossed with other clones of S. × caespitosa or with S. patens and S. pectinata. S. × caespitosa quite frequently occurs and persists under competition amidst juxtaposed clones of rhizomatous S. patens and S. pectinata but there is little evidence of an F2 generation in the wild and it maintains a very localized distribution. Many characteristics of S. × caespitosa are closely similar to those of a species and features of hybrid nature are not easy to define.

scholarly journals Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids

2008 ◽  
Vol 133 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Pablo Bolaños-Villegas ◽  
Shih-Wen Chin ◽  
Fure-Chyi Chen
Keyword(s):  
Cell Division ◽  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Chromosomal Aberrations ◽  
High Frequency ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
High Pollen ◽  
Mother Cells

The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.

Induced tetraploidy and trisomic production of Helianthus annuus L.

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 647-651 ◽  
Author(s):  
C. C. Jan ◽  
J. M. Chandler ◽  
S. A. Wagner
Keyword(s):  
Helianthus Annuus ◽  
Chromosome Pairing ◽  
Chromosome Pair ◽  
Seed Set ◽  
Chromosome Doubling ◽  
Meiotic Chromosome ◽  
Pollen Grains ◽  
Inbred Lines ◽  
Pollen Stainability ◽  
Normal Seed

Seedlings of the Helianthus annuus inbred lines P21 and HA89 were treated with colchicine to study chromosome doubling. Frequency of tetraploids, meiotic chromosome pairing, pollen stainability, and fertility were examined. Five-hour colchicines treatments at 0.15%, pH 5.4, with 2% dimethyl sulfoxide resulted in tetraploid sectors on 42% of P21 and 11% of HA89 plants. Tetraploids had larger disk florets and larger pollen grains. Otherwise, tetraploid plants were morphologically similar to their diploid progenitors. Tetraploidy in P21 was not stable, with plants having 2n = 4x = 65 to 70 chromosomes. Tetraploid plants of HA89 had reduced vigor and did not produce seed. At diakinesis, tetraploid P21 plants had an average of 0.85 univalents, 21.12 open bivalents, 6.66 closed bivalents, 0.21 trivalents, and 2.74 quadrivalents per cell. The number of chiasma per chromosome pair in P21 was reduced from 1.50 for diploid to 1.32 for tetraploid plants. Pollen stainability in tetraploid P21 was less than 50% and the plants produced an average of eight seeds per sibbed head, about 1% of normal seed set. Reciprocal crosses of diploid and tetraploid P21 produced four triploid plants. Backcrossing triploids to P21 produced 137 plants with 2n = 34 to 47 + t. Thirty-one of these plants were trisomies having 2n = 35.Key words: Helianthus annuus, tetraploids, triploids, trisomies.

Genetic control of meiotic chromosome pairing in polyploids in the genus Hordeum

1985 ◽  
Vol 27 (5) ◽  
pp. 515-530 ◽  
Author(s):  
P. K. Gupta ◽  
George Fedak
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Meiotic Chromosome ◽  
Intergeneric Hybrid ◽  
Meiotic Pairing ◽  
Major Locus ◽  
In The Wild ◽  
Hordeum Species ◽  
Homoeologous Chromosomes ◽  
Existing Data

Existing data on meiosis in hexaploid and tetraploid species of Hordeum, their respective polyhaploids, and intergeneric – interspecific hybrids indicate that a meiotic pairing control system exists in this genus. The system is probably polygenic and it is therefore unlikely that a major locus such as Ph in Triticum controls chromosome pairing. It is more efficient in the tetraploids than hexaploids, permitting some intergenomic pairing in the latter. In the polyhaploids the pairing control is somewhat hemizygous ineffective. The pairing of homoeologous chromosomes in the wild polyploid Hordeum species is generally inhibited by H. vulgare and variably enhanced by genomes of Secale species.Key words: Hordeum, synapsis regulation, intergeneric hybrid, polyhaploids, hemizygous.

Failure of chromosome pairing in a probable Desmodium intortum × D. sandwicense hybrid

1968 ◽  
Vol 16 (3) ◽  
pp. 545
Author(s):  
JB Hacker
Keyword(s):  
Chromosome Pairing ◽  
Seed Set ◽  
Tetraploid Plant ◽  
Putative Hybrid ◽  
Pollen Stainability ◽  
Single Flower ◽  
Hybrid Derivative ◽  
Number Of Cells

Failure of chromosome pairing was noted in some plants in the progeny of a putative hybrid derivative of Desmodium intortum and D. sandwicense. Pairing failure resulted in abnormal tetrad formation, the number of cells in each tetrad ranging from one to eight. Pollen stainability was poor but varied considerably, even within a single flower. Seed set in asynaptics was poor or nil. A sample of 30 seedlings derived from a single asynaptic parent was entirely euploid; a single tetraploid plant probably occurred following the fusion of two restitution nuclei.

Inferences from genetical evidence on the course of meiotic chromosome pairing in plants

1977 ◽  
Vol 277 (955) ◽  
pp. 313-326 ◽  
Keyword(s):  
Chromosome Pairing ◽  
Developmental Stages ◽  
Meiotic Chromosome ◽  
Critical Assessment ◽  
Gene Control ◽  
Meiotic Pairing ◽  
Homologous Chromosomes ◽  
Meiotic Chromosome Pairing ◽  
Combined Use ◽  
Or Gene

Meiotic chromosome pairing is a process that is amenable to genetic and experimental analysis. The combined use of these two approaches allows for the process to be dissected into several finite periods of time in which the developmental stages of pairing can be precisely located. Evidence is now available, in particular in plants, that shows that the pairing of homologous chromosomes, as observed at metaphase I, is affected by events occurring as early as the last premeiotic mitosis; and that the maintenance of this early determined state is subsequently maintained by constituents (presumably proteins) that are sensitive to either colchicine, temperature or gene control. A critical assessment of this evidence in wheat and a comparison of the process of pairing in wheat with the course of meiotic pairing in other plants and animals is presented.

scholarly journals Breeding Biology and Success of a Reintroduced Population of the Critically Endangered Puaiohi (Myadestes Palmeri)

The Auk ◽  
2006 ◽  
Vol 123 (3) ◽  
pp. 753-763 ◽  
Author(s):  
Erik J. Tweed ◽  
Jeffrey T. Foster ◽  
Bethany L. Woodworth ◽  
William B. Monahan ◽  
Jherime L. Kellerman ◽  
...  
Keyword(s):  
First Record ◽  
Nesting Success ◽  
Breeding Biology ◽  
Rodent Control ◽  
Breeding Behavior ◽  
Adult Females ◽  
In The Wild ◽  
Daily Nest Survival ◽  
High Predation ◽  
Reintroduced Population

Abstract The ultimate success of reintroduction programs for endangered species depends on the ability of reintroduced animals to breed in the wild. We studied the nesting success and breeding biology of a reintroduced population of Puaiohi (Myadestes palmeri) on the island of Kaua'i, Hawaii. Thirty-four captive-bred Puaiohi were released into the Alaka'i Swamp in 1999-2001 and monitored using radiotelemetry. Ten females and two males paired with wild and other released birds, including one polygynous trio. From March to September, 31 nests were built. Mean clutch size was 2.0 eggs, daily nest survival was 0.97 ± 0.01 (mean ± SE) and overall nest success was 0.40 ± 0.02. We confirmed predation, most probably by rats (Rattus spp.), as the greatest cause of nest failure, occurring at 38% of active nests with known fates, and causing the death of two nesting adult females. Ground-based rodent control proved ineffective at protecting nest attempts. Successful nests fledged an average of 1.4 young each (n = 10), and 85% of fledglings survived at least two weeks. Importantly, breeding behavior and success were comparable to those of wild Puaiohi. This is the first record of breeding in the wild from captive-bred endangered Hawaiian passerines. The ability of captive-bred Puaiohi to survive and breed successfully in the wild bodes well for future releases of this and other endangered passerines, but high predation rates on nests and nesting females highlights the importance of maintaining and restoring safe habitat for recovery. Biología y Éxito Reproductivo de una Población Reintroducida de Myadestes palmeri, una Especie en Peligro Crítico

Meiotic behaviour of induced autotetraploids in Triticum L.

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Yang Yen ◽  
Gordon Kimber
Keyword(s):  
Chromosome Pairing ◽  
Seed Set ◽  
Chromosome Association ◽  
Meiotic Behaviour ◽  
Meiotic Analysis

Colchicine-induced autotetraploids of Triticum speltoides, T. longissimum, T. sharonense, T. bicorne, T. uniaristatum, T. monococcum, and T. tauschii were all morphologically similar to but larger than their diploid forms. Seed set was lower than in the diploids except for the autotetraploid T. speltoides. Meiotic analysis showed fewer quadrivalents and more bivalents than would be expected in all of these autotetraploids. Arm-pair switch, indicated by complex trivalents and quadrivalents, was found and involved 0.1% of total chromosomes in T. umbellulatum, 0.5% in T. longissimum, 0.7% in both T. sharonense and T. tauschii, 6.3% in T. bicorne, and 15.3% in T. uniaristatum.Key words: meiosis, chromosome association, arm-pair switch, chromosome pairing, bivalentization.

Synaptic mutants in hexaploid oats (Avena sativa L.)

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 1-7 ◽  
Author(s):  
H. W. Rines ◽  
S. S. Johnson
Keyword(s):  
Chromosome Pairing ◽  
Sodium Azide ◽  
Avena Sativa ◽  
Seed Set ◽  
Single Gene ◽  
Inheritance Pattern ◽  
Late Prophase ◽  
Homologous Chromosomes ◽  
Breeding Station ◽  
Meiotic Synapsis

Three meiotic synapsis-deficient mutants of oats (Avena sativa L.) were analyzed to determine their inheritance pattern, detailed chromosomal behavior, and location to chromosome. These highly sterile mutants, one in the cultivar 'Stout' and two in 'Noble', had been recovered from progeny of sodium azide mutagenized populations. Each segregated as a single gene recessive. The only synapsis-deficient variants previously described in hexaploid oats have been nullisomics or ditelosomics. Mutant 'Stout 1212' was classified as asynaptic due to deficiencies in chromosome pairing at all meiotic stages. Mutants 'Noble 1362' and 'Noble 1911' were classified as desynaptic since their homologous chromosomes were paired in early meiosis but they disassociated prematurely in late prophase I. Using a partial monosomic series from the Welsh Plant Breeding Station, mutant 1212 was mapped to monosome XII and is probably a mutation in Syn-5, a gene previously defined only by its nulli effect. Mutants 1362 and 1911 were mapped to monosome IV and are probably mutations in Syn-1, a gene also previously defined only by its nulli effect. Seed set on the synaptic mutant plants in the field was less than 0.2% of that on fertile sibs and likely resulted from pollination by surrounding fertile plants. This seed may serve as a source of unique aneuploid stocks in oats.Key words: meiotic mutants, gene mapping, monosomics, nullisomics, oat cytogenetics.

CHROMOSOME PAIRING IN HEXAPLOID TRITICALE

1971 ◽  
Vol 13 (3) ◽  
pp. 621-624 ◽  
Author(s):  
J. B. Thomas ◽  
P. J. Kaltsikes
Keyword(s):  
Durum Wheat ◽  
Normal Level ◽  
Chromosome Pairing ◽  
Tetraploid Wheat ◽  
Meiotic Pairing ◽  
Hexaploid Triticale ◽  
Secale Montanum

A durum wheat background was shown to suppress the meiotic pairing of chromosomes of Secale montanum Guss. with homoeologues of S. cereale L. in hexaploid triticale. This effect was attributed to the activity of the 5BL diploidising system, apparently active in tetraploid wheat. It was considered unlikely that the SBL system was important in conditioning the normal level of pairing failure found in disomic triticales.

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