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.

scholarly journals Cytological Evidence for the Sterility of an Interspecific Alstroemeria Hybrid

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 855B-855
Author(s):  
Chunsheng Lu ◽  
Mark Bridgen
Keyword(s):  
Pollen Mother Cell ◽  
Late Stage ◽  
Interspecific Hybrid ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Cytological Evidence ◽  
Stage Of Development ◽  
Hybrid Plants

Self-pollinations of a diploid (2n = 2x = 16) interspecific hybrid from the cross of Alstroemeria aurea × A. caryophyllaea resulted in no seed set. Pollen viability studies with the hybrid demonstrated that only 5% of the pollen grains were viable. Cytological observations with the hybrid pollen mother cell (PMC) revealed abnormal chromosome behaviors, such as no pairing in Prophase I and Metaphase I, and bridges in the Anaphase I and II. Although the development of microspores appeared normal in shape until the stage of tetrad release, some chromosomes did not remain in the nucleus after completing meiosis, formed isolated groups of 1 to 4, and remained in the cytoplasm. This genetic imbalance of the microspores could be one of the causes for the abortion of the pollen grains in the late stage of development. Additional meiotic cytological studies with colchicine-induced tetraploids (2n = 4x = 32) derived from the hybrid plants showed that chromosome pairings were normal in most cases. However, self-pollination with the tetraploid plants failed to set seeds. These studies with the tetraploids further demonstrate that the sterility of the hybrid is due not only to chromosomal differences, but also to complex genic interactions.

Spontaneous structural rearrangements in Solanum phureja Juz. et Buk. 2. Meiotic behaviour and identification of interchange chromosomes using primary trisomics

Genome ◽  
1995 ◽  
Vol 38 (1) ◽  
pp. 140-147
Author(s):  
M. Wagenvoort
Keyword(s):  
Pollen Mother Cell ◽  
Mother Cell ◽  
Solanum Phureja ◽  
Chromosome Identification ◽  
Structural Rearrangements ◽  
Primary Trisomics ◽  
Interchange Heterozygote ◽  
Mother Cells ◽  
I Cells ◽  
Metaphase I

Meiosis was studied in two diploid (2n = 2x = 24) siblings of Solanum phureja Juz. et Buk. and in 11 disomic and 2 trisomic descendants. The diploid siblings carry the same heterozygous interchange and either one or two inversions. The frequency of quadrivalents at diakinesis/metaphase I in these clones was 0.56 and 0.62 per pollen mother cell. In two plants from the first inbred generation (I1) this frequency was about the same but in some other I1 plants and a full sib the frequency was substantially lower, varying from 0.00 to 0.16. Most quadrivalents, 78–83%, were rings. A variety of quadrivalent configurations at diakinesis and metaphase I was observed, giving rise to balanced and unbalanced gametes. The absence of ring quadrivalents in trisomic descendants of one of the siblings implied that tertiary trisomics or primaries being homozygous for the interchange were present in the I1 generation. Regular chromosome distribution (12–12) at anaphase I occurred in 46.5 and 73.2% of the pollen mother cells studied in the two original clones. Irregularities, such as 11–13 distribution, lagging chromosomes, and a bridge and fragment, were detected on average in 2.7, 3.3, and 32.5%, respectively, of the anaphase I cells analysed. In hybrids from crosses between 6 primary trisomics as females with the interchange heterozygote, the involvement in the interchange of chromosomes 3 and 12 was clearly demonstrated.Key words: Solanum phureja, interchange heterozygote, chromosome identification, interchange trisomic, meiosis.

The potential for diploidizing Lolium multiflorum × L. perenne tetraploids

1985 ◽  
Vol 27 (5) ◽  
pp. 506-509 ◽  
Author(s):  
Taing Aung ◽  
G. M. Evans
Keyword(s):  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Interspecific Hybrid ◽  
Mother Cell ◽  
Lolium Multiflorum ◽  
Genetically Modify ◽  
Hybrid Progeny ◽  
Homoeologous Pairing ◽  
Homologous Chromosomes

The possibility of diploidizing meiosis in tetraploid hybrids of the two closely related Lolium species, L. multiflorum and L. perenne, was investigated using specific genotypes of both parents. Both these parental genotypes had previously been shown to reduce homoeologous pairing in a separate but wider cross with the inbreeder L. temulentum. A preponderance of bivalents was recorded at first metaphase of meiosis in several of the hybrid progeny with the frequency of multivalents being reduced to 0.6/pollen mother cell in one plant. Although it is not unambiguously established that the bivalents so formed are solely between homologous chromosomes, it is highly likely that this is so. It is concluded that it is feasible to genetically modify the pattern of meiosis even in tetraploid hybrids of species of similar karyotypes.Key words: chromosome pairing, Lolium, interspecific hybrid.

Meiotic crossing-over between sites on opposite sides of the centromeres of homoeologues is frequent in hybrid Aloeaceae

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 170-176 ◽  
Author(s):  
P. E. Brandham
Keyword(s):  
Pollen Mother Cell ◽  
Mother Cell ◽  
Crossing Over ◽  
Centromere Region ◽  
Short Chromosome ◽  
Pollen Mother Cells ◽  
Mother Cells ◽  
Homoeologous Chromosomes

During meiosis, long and short arms of acrocentric homoeologues pair and cross over in the centromere region in 95 (66.9%) of 142 hybrids of differing parentage in the monocotyledon family Aloeaceae. A characteristic configuration, the L–S bridge, is produced at anaphase I with frequencies ranging from <1 to 48% of pollen mother cells and in up to three bivalents per pollen mother cell. Too frequent to be due to inversion hybridity, L–S crossing-over most probably results from straight, noninverted pairing between nonhomologous proximal segments of the long and short chromosome arms following centromere mismatching in the heteromorphic bivalents. It is suggested that there are several lengths of DNA in different regions of homoeologous chromosomes, but perhaps concentrated around the centromere, that are sufficiently similar to recognize each other, pair, and cross over when brought together in a heteromorphic bivalent with mismatching of centromeres.Key words: Aloeaceae, hybrid, meiosis, nonhomologous pairing, crossing-over.

scholarly journals Reproductive biology and pollination of Cabomba aquatica (Cabombaceae)

Rodriguésia ◽  
2011 ◽  
Vol 62 (4) ◽  
pp. 919-926 ◽  
Author(s):  
Jacilene Bezerra da Silva ◽  
Ana Virgínia de Lima Leite
Keyword(s):  
Reproductive Biology ◽  
High Frequency ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Pollen Flow ◽  
Northeastern Brazil ◽  
Nectar Production ◽  
High Pollen ◽  
Pollinator Behavior ◽  
Effective Pollinators

Abstract Reproductive biology and pollination of the fanwort, Cabomba aquatica Aubl., were studied in populations from dams located in Dois Irmãos State Park, Recife, Pernambuco state, northeastern Brazil. Flower anthesis in this species is diurnal and lasts two days. The flowers are bisexual and exhibit herkogamy and incomplete protogyny. Each flower produces an average of 2.1 ± 94.8 pollen grains, with a P/O ratio of 1.055 and high pollen viability (99.7%). This species is self-compatible, but requires biotic vectors to transfer pollen. We observed visits of bees (Apidae and Halictidae), wasps (Vespidae) and flies (Diptera) to the flowers. Bees and wasps were considered to be effective pollinators, both due to their behavior and their high frequency of visits to flowers, whereas flies were considered to be occasional pollinators. The floral mechanism (herkogamy and protogyny), together with low nectar production and pollinator behavior during visits, may contribute to increase pollen flow between individuals.

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 Reduced pollen viability and achene development in Solidago ×niederederi Khek from Poland

2014 ◽  
Vol 83 (3) ◽  
pp. 251-255 ◽  
Author(s):  
Grzegorz Migdałek ◽  
Jolanta Kolczyk ◽  
Artur Pliszko ◽  
Maria Kościńska-Pająk ◽  
Aneta Słomka
Keyword(s):  
Invasive Species ◽  
Vegetative Propagation ◽  
Interspecific Hybrid ◽  
High Frequency ◽  
Seed Set ◽  
Parental Species ◽  
Pollen Viability ◽  
Viable Pollen ◽  
Ne Poland ◽  
Potential Impact

Pollen and achene characters of natural interspecific hybrid <em>Solidago</em> ×<em>niederederi</em> Khek were analyzed and compared with putative parental species <em>S. virgaurea</em> L. and <em>S. canadensis</em> L. to estimate the level of disturbances in generative reproduction resulting from its hybrid nature. Pollen viability (stainability) of <em>Solidago</em> ×<em>niederederi</em> from one newly discovered locality in NE Poland was evidently reduced to ~65% in both viability tests (acetocarmine and Alexander). The diameter of viable pollen (median 21.11 µm) fell between <em>S. canadensis</em> (median 19.52 µm) and <em>S. virgaurea</em> (median 23.48 µm). Both parental species produced normally developed achenes with high frequency (~90%) whereas in the hybrid, the seed set was dramatically low (6%). The results clearly indicated that sexual reproduction of hybridogenous taxon <em>S.</em> ×<em>niederederi</em> is disturbed, and its potential impact as an invasive species depends mainly on vegetative propagation.

Sterility in Wheat (Triticum aestivum L.) Induced by Water Deficit or High Temperature: Possible Mediation by Abscisic Acid

1982 ◽  
Vol 9 (5) ◽  
pp. 529 ◽  
Author(s):  
HS Saini ◽  
D Aspinall
Keyword(s):  
Triticum Aestivum ◽  
Abscisic Acid ◽  
High Temperature ◽  
Water Stress ◽  
Pollen Mother Cell ◽  
Mother Cell ◽  
Triticum Aestivum L ◽  
Pollen Sterility ◽  
Mother Cells ◽  
Abscisic Acid Content

The application of abscisic acid solution to developing spikes of wheat (cv. Gabo) via wicks threaded through peduncles at the stage of meiosis in pollen mother cells caused pollen sterility without affecting female fertility. The concentration of abscisic acid measured in the spikelets of plants treated in this manner was close to that induced by water stress, which produced a similar level of pollen sterility. After pollen mother cell meiosis, treatment with abscisic acid had no effect on pollen fertility, as has been shown previously with water stress. Abscisic acid applied immediately before meiosis reduced fertility, in contrast to the effect of water stress, but this may have been due to persistence of the hormone in the plant. High temperature during pollen mother cell meiosis had no effect on the endogenous abscisic acid content of the spikelets, even where the treatment caused a complete inhibition of grain set.

Implications of chromosome pairing in a monohaploid and its colchidiploid of Solanum tuberosum (x = 12)

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 347-351 ◽  
Author(s):  
A. K. Singh ◽  
H. Uhrig ◽  
F. Salamini
Keyword(s):  
Solanum Tuberosum ◽  
Chromosome Pairing ◽  
Equatorial Plane ◽  
High Frequency ◽  
Mother Cell ◽  
Chromosome Complement ◽  
Meiotic Analysis ◽  
Parallel Orientation ◽  
Parent Clone ◽  
Pairing Behaviour

A monohaploid (x = 12) of Solanum tuberosum, its colchidiploid and their 2n parent clone have been cytologically examined. The meiotic analysis of the monoploid shows a certain degree of pairing at pachytene with a high frequency of bivalents at metaphase I. The bivalent frequency ranges from 2.07 to 3.0 per pollen mother cell (PMC). The most frequent classes are 3II + 6I and 2II + 8I. Several PMCs show secondary associations. At anaphase I (AI), the chromosomes distribute frequently in groups of 7 to 5 (32% of PMCs) and 6 to 6 (30% of PMCs). Occasionally, however, both disjunct chromosomes and univalents remain at the equatorial plane and divide with or without segregation, resulting in the formation of dyads or monads. The PMCs with a regular AI show a parallel orientation of spindles as well as a normal one, a situation that ends at telophase II with dyads, triads, and tetrads but 0% pollen fertility. The overall frequency of monads, dyads, triads, and tetrads is equal to 13, 69, 7 and 11%, respectively. Both in the parent clone and in the 2n colchidiploid clone, chromosome pairing is normal. The pairing behaviour in the monohaploid suggests the presence of duplicated sequences in the chromosome complement. An alteration of genes controlling the level of pairing is excluded.Key words: monohaploid, colchidiploid, chromosome pairing, meiosis.

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