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 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.

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

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.

The effect of practicing yoga during pregnancy on labor stages length, anxiety and pain: a randomized controlled trial

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ellahe Mohyadin ◽  
Zohreh Ghorashi ◽  
Zahra Molamomanaei
Keyword(s):  
Controlled Trial ◽  
Intervention Group ◽  
Total Duration ◽  
Measurement Data ◽  
Labor Pain ◽  
Control Group ◽  
Chi Square ◽  
Nulliparous Women ◽  
Two Stages ◽  
And Control

AbstractBackgroundAnxiety and fear of labor pain has led to elevated cesarean section rate in some countries. This study was conducted to investigate the effect of yoga in pregnancy on anxiety, labor pain and length of labor stages.MethodsThis clinical trial study was performed on 84 nulliparous women who were at least 18 years old and were randomly divided into two groups of yoga and control groups. Pregnancy Yoga Program consisting of 6 60-min training sessions was started every 2 weeks from week 26 of pregnancy and continued until 37 weeks of gestation. Anxiety severity at maternal admission to labor was measured by the Spielbergers State-Trait Anxiety Inventory, and labor pain was measured by Visual Analogue Scale (VAS) at dilatation (4–5 cm) and 2 h after the first measurement. Data were analyzed using Chi-Square and t-test.ResultsIntervention group reported less pain at dilatation (4–5 cm) (p=0.001) and 2 h after the first measurement (p=0.001) than the control group. Stat anxiety was also lower in intervention group than the control group (p=0.003) at the entrance to labor room. Subjects in the control group required more induction compared to intervention group (p=0.003). Women in intervention group experienced shorter duration of the first phase of the labor than the control group (p=0.002). Also, the total duration of two stages of labor was shorter in intervention group than the control group (p=0.003).ConclusionsPracticing yoga during pregnancy may reduce women’s anxiety during labor; shorten labor stages, and lower labor pain.

The formation of the tryphine coating the pollen grains of Raphanus , and its properties relating to the self-incompatibility system

1973 ◽  
Vol 184 (1075) ◽  
pp. 149-165 ◽  
Keyword(s):  
Granular Material ◽  
Pollen Grains ◽  
The Self ◽  
Self Incompatibility ◽  
Pollen Maturation ◽  
Incompatible Pollen ◽  
Incompatibility System ◽  
Two Stages ◽  
Stimulation Of ◽  
Incompatible Pollen Tube

The tryphine that coats the pollen grains of Raphanus is tapetally synthesized and is composed of a fibro-granular and a lipidic component. The fibro-granular material is proteinaceous and is secreted by cisternae of the endoplasmic reticulum. The lipidic component is derived, mainly, from degraded elaioplasts. The fibro-granular material is applied to the pollen exine first, followed by the lipidic mass. The tryphine condenses during the final stages of pollen maturation and dries down to form a thick, highly viscous coating. The major part of the condensation appears to result from dehydration. The tryphine, extracted from the pollen by a centrifugal method and mounted in a membrane, appears to be capable of penetrating the outer layers of a stigma of the same species and, if the pollen from which it was derived is incompatible with respect to the stigma, the stimulation of the production of the callosic reaction body in a manner similar to an incompatible pollen tube. It is proposed that, in Raphanus , substances responsible for the initiation of at least two stages in the self-incompatibility system are held in the tryphine.

EFFECT OF RYE ON HOMOEOLOGOUS CHROMOSOME PAIRING IN WHEAT × RYE HYBRIDS

1977 ◽  
Vol 19 (3) ◽  
pp. 549-556 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Triticum Aestivum L ◽  
Homoeologous Chromosome ◽  
Wheat Genotype ◽  
Hybrid Plants ◽  
Homoeologous Chromosome Pairing ◽  
Secale Cereale L ◽  
Polygenic System

The number of chiasmata per cell at metaphase I was scored in eight haploid plants of Triticum aestivum L. emend. Thell. cv. 'Chinese Spring' and 100 hybrid plants of Chinese Spring × Secale cereale L. Mean chiasma frequency per cell ranged from 0.00 to 3.59 in the hybrids and from 0.17 to 0.35 in the haploids. Since the same wheat genotype was present in both the haploids and hybrids, it is concluded that some of the rye genotypes promoted homoeologous chromosome pairing. The absence of distinct segregation classes among the hybrids suggests that these genes constitute a polygenic system.

Effect of chromosome 1B, chromosome 6B, and low temperature on the frequency of chromosome pairing at first meiotic metaphase in hexaploid triticale

1983 ◽  
Vol 25 (3) ◽  
pp. 278-282
Author(s):  
Julian B. Thomas ◽  
P. J. Kaltsikes ◽  
S. Shigenaga
Keyword(s):  
Low Temperature ◽  
Common Wheat ◽  
Chromosome Pairing ◽  
Meiotic Metaphase ◽  
The Other ◽  
Hexaploid Triticale ◽  
Other Hand

Chromosome 1B in 'Rosner' and chromosome 6B in line 125 both reduced the frequency with which chromosomes were paired at first meiotic metaphase of hexaploid triticale. On the other hand, chromosome 6B in 'Rosner' and chromosomes 1B and 6B in line 110 had no such effect. The 1B pairing suppressor in 'Rosner' was located on the short arm of the chromosome (1Bs). Between 10 and 30 °C, pairing frequency was quite stable in 'Rosner' triticale in comparison with common wheat, although the level was consistently lower in the triticale. Some reduction of pairing frequency was noted at 10 °C in 'Rosner'. This effect of low temperature did not interact with 1B dosage to cause a disproportionate decrease in pairing frequency when plants with high 1B dosage were grown at 10 °C.

Sign in / Sign up

Export Citation Format

Share Document