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

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.

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Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.133.1.107 ◽

2008 ◽

Vol 133 (1) ◽

pp. 107-116 ◽

Cited By ~ 5

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.

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

Journal of Cell Science ◽

10.1242/jcs.97.3.565 ◽

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.

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

Genome ◽

10.1139/g95-017 ◽

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.

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

Functional Plant Biology ◽

10.1071/pp9820529 ◽

1982 ◽

Vol 9 (5) ◽

pp. 529 ◽

Cited By ~ 49

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.

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The time and duration of female meiosis in Lilium

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1975.0031 ◽

1975 ◽

Vol 188 (1093) ◽

pp. 459-475 ◽

Cited By ~ 14

Keyword(s):

Mother Cell ◽

Embryo Sac ◽

Female Meiosis ◽

Flower Bud ◽

Pollen Mother Cells ◽

Controlled Conditions ◽

Mean Temperature ◽

Mother Cells ◽

Black Beauty

The time and duration of meiosis in ovules and anthers was estimated in plants of two Lilium hybrids (cultivars ‘Sonata’ and ‘Black Beauty’) grown under controlled conditions. Within each flower bud meiosis did not start in the embryo sac mother cell (e.m.c.) until about the time when meiosis in pollen mother cells (p.m.cs) was ended. In both cultivars meiosis lasted about 50% longer in e.m.cs than in p.m.cs. Thus, at a mean temperature of 20 ± 1 °C meiosis in ‘Sonata’ took 7.5 days in p.m.cs and 10.5 days in e.m.cs, while in ‘Black Beauty’ it took 10.5 days in p.m.cs and 16.0 days in e.m.cs.

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Comparison of crossover frequencies in barley (Hordeum vulgare) and H. vulgare × H. bulbosum hybrids using a paracentric inversion

Genome ◽

10.1139/g91-102 ◽

1991 ◽

Vol 34 (4) ◽

pp. 666-673 ◽

Cited By ~ 12

Author(s):

R. A. Pickering

Keyword(s):

Hordeum Vulgare ◽

Paracentric Inversion ◽

Chromosome 3 ◽

Crossing Over ◽

Gene Introgression ◽

Hordeum Bulbosum ◽

Hordeum Vulgare L ◽

Meiotic Analyses ◽

Mother Cells ◽

Homoeologous Chromosomes

Crosses between different parental ploidy combinations of barley (Hordeum vulgare L.) and H. bulbosum L. have been carried out principally to obtain hybrids with high allosyndetic chromosome pairing. Fertility has been observed in tetraploid and triploid hybrids, but there has been little evidence of gene introgression from H. bulbosum into H. vulgare in their progeny. To investigate whether crossing-over takes place between homoeologous chromosomes of H. vulgare and H. bulbosum, diploid hybrids were obtained from crosses between a barley mutant (wst3) homozygous for a paracentric inversion on chromosome 3 and one H. bulbosum genotype. Meiotic analyses at metaphase I and anaphase I and II were carried out on several viable hybrids and compared with control diploid hybrids without the inversion and H. vulgare plants heterozygous for the inversion. Aberrations (bridges and (or) fragments) in H. vulgare × H. bulbosum pollen mother cells at anaphase I were significantly less frequent than in the barley hétérozygote. It is concluded that reduced crossing-over between the parental chromosomes in hybrids contributes to the lack of success in obtaining genetic recombinations between the two species.Key words: Hordeum vulgare, Hordeum bulbosum, interspecific hybrid, paracentric inversion, crossing-over.

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