Genetic Variation in Chromosome Pairing

Riley, Ralph; Law, C. N.

doi:10.1016/s0065-2660(08)60047-4

Cited by 256 publications

(106 citation statements)

References 110 publications

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“…For Ppd2 to be distal to and independent of Sri 6 would call for a map distance in excess of 120 centimorgans on the long arm. Such a map distance is very unlikely in wheat where the mean chiasma frequencies per arm are invariably less than two, indicating a distance of less than 100 centimorgans (Riley and Law, 1965).…”

Section: /74 =049±0057mentioning

confidence: 99%

The location of the photoperiod gene, Ppd2 and an additional genetic factor for ear-emergence time on chromosome 2B of wheat

1983

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SUMMARYThe major photoperiod gene Ppd2 was identified on chromosome 2B of wheat using homozygous recombinant lines developed from a cross between Chinese Spring (CS) and the substitution line CS (Marquis 2B). Genetic analysis of these lines, using disease marker genes on the long arm of chromosome 2B, the yellow rust (Puccinia striiformis) gene Yr7 and the stem rust (P. gra minis) genes Sr9g and Sr16, showed these genes segregated independently from Ppd2. It was concluded that Ppd2 is located on the short arm of chromosome 2B. The classification of the disease resistance genes was used to identify a second gene (s) influencing the ear emergence time of the lines within each of the Ppd2 and ppd2 gene classes. The second gene(s) was associated with the disease genes on the long arm of chromosome 2B. The early allele of this gene(s) was found on Marquis chromosome 2B and the late on Chinese Spring 2B, so that early alleles of the two gene(s) influencing ear emergence time in this study were dispersed between the parental chromosomes.Following a winter sowing in the field, differences in ear emergence time were associated with the Ppd2 locus and the gene(s) on the long arm. Following a spring sowing, differences were confined to the gene(s) on the long-arm only. This confirms the photoperiodic sensitivity of Ppd2 and suggests that the second genetical effect was acting independently of the environment.

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Section: /74 =049±0057mentioning

confidence: 99%

The location of the photoperiod gene, Ppd2 and an additional genetic factor for ear-emergence time on chromosome 2B of wheat

1983

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“…Also failure of homologous pairing in the inverted segment at zygotene will lead to nonhomologous pairing with a synaptonemal complex at mid pachytene. The genetic control mechanisms for avoiding chiasma formation between homoeologous chromosomes operative in hexaploid wheat (27,28), Avena (15) and Festuca (15) may also involve the two phase pairing system.…”

Section: Chromosome Pairingmentioning

confidence: 99%

Chromosome pairing in autotetraploid Bombyx females. Mechanism for exclusive bivalent formation

Rasmussen

Holm

1979

Carlsberg Res. Commun.

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Meiosis in tetraploid Bombyx mori oocytes has been analyzed by three dimensional reconstructions of 1 mid zygotene, 7 early pachytene and 11 mid-late pachytene nuclei. The general pattern of chromosome pairing was found to be essentially similar to that of diploid oocytes. The zygotene stage is recognizable by incomplete pairing and a distinct chromosome bouquet, early pachytene by complete or almost complete pairing and a distinct bouquet and mid-late pachytene by dissolution of the bouquet followed by release of chromosome ends from their attachment sites on the nuclear envelope. At early pachytene the nuclei contained 5-12 quadrivalents, 0-7 univalents, 0-3 trivalents and 27-44 bivalents. The corresponding figures for mid-late pachytene were 0-2 quadrivalents, 0-3 univalents, 0-2 trivalents and 48-56 bivalents. The remarkable decrease in the number of quadrivalents and the corresponding increase in the number of bivalents between early and mid-late pachytene is the result of a correction of the zygotene pairing. In the absence of crossing over and chiasma formation, the pairing of the randomly located leptotene chromosomes into the maximal number of bivalents consists thus of two phases: 1) A specific zygotene pairing with synaptonemal complex formation restricted to homologous chromosome regions and 2) a correction of irregularities in this pairing by partial, dissolution of the central region of the complex succeeded by or coinciding with a second round of synaptonemal complex formation, permitting also nonhomologous pairing. It is suggested that in organisms with crossing over and chiasma formation the correction process is impeded by the occurrence of crossovers.

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“…The heterozygosity produced in the intervarietal hybrid of Ae. variabilis might be responsible for the decrease in association frequency as suggested by Riley & Law (1965) in intervarietal hybrids of common wheat. Both factors could lead to a decrease in the frequency of chromosome association not only in the intervarietal hybrid but also in the interspecific hybrids between Ae.…”

Section: Discussionmentioning

confidence: 91%

Genomic analysis in the genus Aegilops. II. Interspecific hybrids between polyploid species sharing two common genomes

Cuñado

1993

Heredity

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Hybrids between polyploid Aegilops species sharing two common genomes were analysed at metaphase I by using a C-banding technique in order to establish genome relationships. In all cases it allowed discrimination between associations of chromosomes with similar morphology and C-banding belonging to the same genomes (homomorphic associations) and associations involving different chromosomes (heteromorphic associations). In the hybrids involving Ac. variabilis and Ae. kotschyi, (UUSS), it was also possible to identify the U and S genomes, which are shared by the tetraploid species, and their analysis indicated that the genomes of both species are essentially unaltered. However, the data of the Ae. crassa(6x) XAe. vavilovii (DDDMMN) hybrid showed that the divergences between the shared genomes are at present substantial despite their common origin. By contrast, in the case of the Ae. triaristata(6x) X Ae. triaristata(4x) (UUMMN) hybrid the data did not confirm that the hexaploid species arose from the tetraploid one.

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Genetic Variation in Chromosome Pairing

Cited by 256 publications

References 110 publications

The location of the photoperiod gene, Ppd2 and an additional genetic factor for ear-emergence time on chromosome 2B of wheat

The location of the photoperiod gene, Ppd2 and an additional genetic factor for ear-emergence time on chromosome 2B of wheat

Chromosome pairing in autotetraploid Bombyx females. Mechanism for exclusive bivalent formation

Genomic analysis in the genus Aegilops. II. Interspecific hybrids between polyploid species sharing two common genomes

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