THE EFFECT OF WHEAT CYTOPLASM ON MEIOSIS OF HEXAPLOID TRITICALE

1977 ◽  
Vol 19 (1) ◽  
pp. 39-49 ◽  
Author(s):  
D. G. Roupakias ◽  
P. J. Kaltsikes
Keyword(s):  
Chromosome Pairing ◽  
Hexaploid Wheat ◽  
Mother Cell ◽  
Significant Positive Correlation ◽  
Total Duration ◽  
Continuous Illumination ◽  
Sufficient Time ◽  
Hexaploid Triticale ◽  
Paired Chromosome ◽  
Triticosecale Wittmack

The interrelationships among source of cytoplasm, chromosome pairing and the duration of meiosis were studied in eight combinations of hexaploid triticale (× Triticosecale Wittmack) grown at 20 °C under continuous illumination. The number of paired chromosome arms and univalents per pollen mother cell at MI ranged from 32.32 and 4.89 to 37.26 and 1.37, respectively. Meiosis lasted from 44.14 to 49.35 hours. A significant positive correlation (r = 0.92) was found between total duration of meiosis and the combined duration of zygotene and pachytene, the stages during which chromosome pairing is thought to occur. The origin of the cytoplasm (from tetraploid or hexaploid wheat) had no significant effect of chromosome pairing or meiotic duration. No relationship was found between total duration of meiosis, or that of zygotene and pachytene, and chromosome pairing. It was concluded that lack of sufficient time for homologues to pair cannot account for the presence of rye chromosomes as univalents in triticaie.

INDEPENDENCE OF DURATION OF MEIOSIS AND CHROMOSOME PAIRING IN HEXAPLOID TRITICALE

1977 ◽  
Vol 19 (2) ◽  
pp. 345-354 ◽  
Author(s):  
D. G. Roupakias ◽  
P. J. Kaltsikes
Keyword(s):  
Chromosome Pairing ◽  
Total Duration ◽  
Limiting Factor ◽  
Genotypic Differences ◽  
Strong Positive Correlation ◽  
Hexaploid Triticale ◽  
Pollen Maturation ◽  
Secale Cereale L ◽  
Two Stages ◽  
Triticosecale Wittmack

The duration of meiosis, its stages, and pollen maturation at 20 °C were determined in six hexaploid triticales (× Triticosecale Wittmack) which differed in the number of univalents per pollen mother cell at metaphase I (0.67 to 2.43). Meiosis lasted from 46.5 to 53.3 h; these estimates are longer than others previously reported for hexaploid triticale (34–37 h) grown under the same conditions. The quartet stage lasted from 7.1 to 8.0 h while pollen maturation took from 9.5 to 11.2 days. Apart from possible genotypic differences, and subjective judgements as to the beginning of meiosis, the present estimates include the stage of nucleolar fusion (average duration 6.0 h) as part of meiotic prophase. A strong positive correlation (r = 0.99) was found between total duration of meiosis and that of zygotene plus pachytene, the stages during which chromosome pairing is thought to occur. These two stages combined accounted for approximately 46% of the total duration of meiosis; even in the triticale with the shortest meiotic duration these two stages lasted longer than in rye (Secale cereale L.). As no relationship could be demonstrated between the total duration of meiosis, or of zygotene plus pachytene, and the number of univalents per PMC, it is concluded that time is not a limiting factor for chromosome pairing in triticale.

THE EFFECT OF COLCHICINE ON CHROMOSOME PAIRING

1977 ◽  
Vol 19 (2) ◽  
pp. 231-249 ◽  
Author(s):  
J. B. Thomas ◽  
P. J. Kaltsikes
Keyword(s):  
Aqueous Solution ◽  
Chromosome Pairing ◽  
Close Association ◽  
Tetraploid Wheat ◽  
Continuous Illumination ◽  
Hexaploid Triticale ◽  
Homologous Chromosomes ◽  
Wheat Hybrids ◽  
Bouquet Stage

Beginning at 120 hours prior to first metaphase of meiosis (MI) a 0.03% aqueous solution of colchicine was injected into the boot of pentaploid (hexaploid triticale × tetraploid wheat) hybrids developing at 20 °C ± 1° under continuous illumination. Colchicine applied 40 h or less prior to MI had no effect on chromosome pairing, while its application 40 h or more prior to MI induced a steady decline, culminating in a 40% reduction in chromosome pairing at about 80 h from MI. Between 48 and 35 h before MI (late premeiotic interphase to early zygotene) meiocytes underwent a period of active nucleolar fusion. The time, therefore, at which the colchicine sensitive aspects of chromosome pairing were completed coincided with the completion of nucleolar fusion. From comparison with other findings it was concluded that there is a colchicine sensitive bouquet stage which appears in leptotene and early zygotene; this bouquet is responsible for active nucleolar fusion and final close association between homologous chromosomes.

QUANTITATIVE RELATIONSHIPS OF CELLULAR PROTEIN, RNA, AND NUCLEARHISTONE IN HEXAPLOID TRITICALE AS INFLUENCED BY SOURCE OF WHEAT CYTOPLASM

1974 ◽  
Vol 16 (3) ◽  
pp. 619-625 ◽  
Author(s):  
S. L. K. Hsam ◽  
E. N. Larter
Keyword(s):  
Hexaploid Wheat ◽  
Tetraploid Wheat ◽  
Cellular Protein ◽  
Agronomic Performance ◽  
Hexaploid Triticale ◽  
Total Cellular Protein ◽  
Nuclear Histone ◽  
Triticosecale Wittmack ◽  
Related Compounds

Reciprocal F1 hybrids of hexaploid triticale (× Triticosecale Wittmack) differing only in their source of wheat (Triticum sp.) cytoplasm were studied to determine its influence on the synthesis of cellular protein and related compounds. Microphotometric methods revealed higher levels of total cellular protein and RNA in triticales with hexaploid-wheat cytoplasm (T. aestivum L. em Thell) than those with tetraploid wheat cytoplasm (T. durum Desf.). Conversely a higher level of nuclear histone was found in tritical hybrids possessing tetraploid wheat cytoplasm. The utilization of hexaploid-wheat cytoplasm in the improvement of the agronomic performance of hexaploid triticale is suggested.

GENOMIC EFFECTS ON THE DURATION OF MEIOSIS IN TRITICALE AND ITS PARENTAL SPECIES

1977 ◽  
Vol 19 (2) ◽  
pp. 331-343 ◽  
Author(s):  
D. G. Roupakias ◽  
P. J. Kaltsikes
Keyword(s):  
Triticum Aestivum ◽  
Ploidy Level ◽  
Parental Species ◽  
Total Duration ◽  
Triticum Aestivum L ◽  
Continuous Illumination ◽  
D Genome ◽  
Secale Cereale L ◽  
Genomic Effects ◽  
Triticosecale Wittmack

The effect of the D and R genomes on the duration of meiosis and its stages was studied in the following materials: 1. AABBDD (Triticum aestivum L. em. Thell.); 2. AABB (extracted from AABBDD); 3. AABBRR and AABBDDRR (× Triticosecale Wittmack); 4. AABBD; 5. ABRR; and 6. RR (Secale cereale L.). Genomes AB, D and R were the same irrespective of the material in which they were found. At 20 °C and continuous illumination meiosis lasted 32.8 to 44.5 h in the AABBDD; 44.1 to 44.6 h in the AABB; 46.4 to 51.3 h in the AABBRR; 43.6 h in the AABBDDRR; 44.5 h in the AABBD; 51.6 to 52.7 h in the ABRR and 52.6 h in the RR genotype. Addition of the D genome to the AABB and AABBRR genotypes resulted in (1) elongation of the stage of nucleolar fusion (2) shortening of the combined duration of zygotene and pachytene and (3) reduction of the total duration of meiosis in AABBRR while it had no effect on AABB. Addition of the R genome to AABB resulted in the elongation of the total duration of meiosis and its stages while it had no significant effect when added to AABBDD. It was concluded that the variation observed in the duration of meiosis and its stages among the various cereal genotypes studied was more likely due to genes carried by the D and R genomes rather than to simple changes in ploidy level or DNA content.

THE EFFECT OF TELOMERIC HETEROCHROMATIN ON CHROMOSOME PAIRING OF HEXAPLOID TRITICALE

1977 ◽  
Vol 19 (3) ◽  
pp. 543-548 ◽  
Author(s):  
D. G. Roupakias ◽  
P. J. Kaltsikes
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Metaphase ◽  
Single Plant ◽  
Hexaploid Triticale ◽  
Telomeric Heterochromatin ◽  
Triticosecale Wittmack

Plants carrying (++) or lacking (−−) most of the telomeric heterochromatic band on the short arm of chromosome 6R(6RS) were isolated from a single plant progeny of Rosner triticale (× Triticosecale Wittmack) heterozygous for this band. Chromosome pairing at first meiotic metaphase was significantly higher in −− than in ++ or +− plants. The changes in chromosome pairing were likely due to the 6RS telomeric heterochromatin which affected the pairing not only of the arm carrying it but of other chromosomes as well.

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.

Suppression of homologous pairing between chromosomes of A and B genomes of 4x and 6x wheats by Hordeum californicum Covas and Stebbins

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 8-11
Author(s):  
H. S. Balyan ◽  
G. Fedak
Keyword(s):  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chiasma Frequency ◽  
Mother Cell ◽  
Triticum Turgidum ◽  
Regulatory Gene ◽  
Intergeneric Hybrids ◽  
Homologous Pairing ◽  
Meiotic Analysis ◽  
Hybrid Plants

Three hybrids of Triticum turgidum cv. Ma with Hordeum californicum × T. aestivum cv. Chinese Spring amphiploid were obtained at a frequency of 1.6% of the pollinated florets. Meiotic analysis of the hybrid plants revealed an average chiasma frequency per pollen mother cell ranging from 15.27 to 17.60. The lower than expected chromosome pairing in the hybrid plants was attributed to the suppression of pairing between homologous wheat chromosomes by pairing regulatory gene(s) in H. californicum.Key words: intergeneric hybrids, Hordeum californicum, Triticum turgidum, meiosis, chromosome pairing.

Cluster Headache: Severity and Temporal Profiles of Attacks and Patient Activity Prior to And During Attacks

Cephalalgia ◽  
1981 ◽  
Vol 1 (4) ◽  
pp. 209-216 ◽  
Author(s):  
David Russell
Keyword(s):  
Clinical Study ◽  
Cluster Headache ◽  
Short Duration ◽  
Refractory Period ◽  
Significant Positive Correlation ◽  
Total Duration ◽  
Rapid Onset ◽  
Headache Severity ◽  
Significant Difference ◽  
Temporal Profiles

A detailed clinical study of 77 spontaneous cluster headache attacks has been carried out. The information was recorded during a period when patients were without medication and with the use of methods which were not dependent on the patients' memory of events. The findings stress the usual rapid onset and termination of attacks, and their short duration. There was a preponderance of attacks beginning during sleep and the majority of daytime attacks began when patients were physically relaxed. No significant difference between nocturnal and daytime attacks was found as regards severity or temporal profiles. A significant positive correlation was found between severity of maximal pain and both duration of maximal pain and total duration of attacks. “Abortive attacks” accounted for 16% of attacks. The apparent spontaneous arrest of these attacks does not appear to be due to special features of patient activity prior to or during attacks, nor are they restricted to a refractory period following more severe attacks.

COLD HARDINESS IN HEXAPLOID TRITICALE

1985 ◽  
Vol 65 (3) ◽  
pp. 487-490 ◽  
Author(s):  
A. E. LIMIN ◽  
J. DVORAK ◽  
D. B. FOWLER
Keyword(s):  
Cold Hardiness ◽  
Tetraploid Wheat ◽  
Triticum Aestivum L ◽  
Hexaploid Triticale ◽  
D Genome ◽  
Potential Source ◽  
Secale Cereale L ◽  
Cold Hardy ◽  
Triticosecale Wittmack ◽  
X Triticosecale Wittmack

The excellent cold hardiness of rye (Secale cereale L.) makes it a potential source of genetic variability for the improvement of this character in related species. However, when rye is combined with common wheat (Triticum aestivum L.) to produce octaploid triticale (X Triticosecale Wittmack, ABDR genomes), the superior rye cold hardiness is not expressed. To determine if the D genome of hexaploid wheat might be responsible for this lack of expression, hexaploid triticales (ABR genomes) were produced and evaluated for cold hardiness. All hexaploid triticales had cold hardiness levels similar to their tetraploid wheat parents. Small gains in cold hardiness of less than 2 °C were found when very non-hardy wheats were used as parents. This similarity in expression of cold hardiness in both octaploid and hexaploid triticales indicates that the D genome of wheat is not solely, if at all, responsible for the suppression of rye cold hardiness genes. There appears to be either a suppressor(s) of the rye cold hardiness genes on the AB genomes of wheat, or the expression of diploid rye genes is reduced to a uniform level by polyploidy in triticale. The suppression, or lack of expression, of rye cold hardiness genes in a wheat background make it imperative that cold-hardy wheats be selected as parents for the production of hardy triticales.Key words: Triticale, Secale, winter wheat, cold hardiness, gene expression

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