Evidence for preferential pairing in telotrisomic plants of rye

Benavente, Elena; Orellana, Juan

doi:10.1038/hdy.1985.90

Cited by 4 publications

(3 citation statements)

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“…We now include the comparison of anthers within a spike, where, in contrast with the great differences between tillers of the same plants, no or very little variation was found. In the study of Benavente and Orellana (1985) on C-banded metaphase I preparations of marked telotrisomics of rye chromosome 1RS using limited material, few within-plant replications were reported. Qi et al (1988) analyzed synaptonemal complex and metaphase I configurations of C-banded telotrisomics of chromosome 1RS of rye, where one chromosome 1R was replaced by the corresponding two telocentrics (telocentric substitution).…”

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Epigenetic Control May Explain Large Within-Plant Heterogeneity of Meiotic Behavior in Telocentric Trisomics of Rye

2008

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In telocentric trisomics (telotrisomics) of organisms in which the chromosomes normally have two distinct arms, a single chromosome arm with a centromere is present in addition to a complete diploid set of chromosomes. It is the simplest form of polysomy and suitable for analyzing meiotic pairing and recombination patterns in situations where chromosomes compete for pairing. When no suitable meiotic chromosome markers are available, four metaphase I configurations can be distinguished. Their relative frequencies are indicative of the pairing and recombination patterns. In short arm (1RS) telotrisomics of chromosome 1R of rye (Secale cereale) we observed great differences in pairing and recombination patterns among spikes from different tillers and clones of the same plants. Anthers within spikes were only very rarely different. We analyzed a large number of genotypes, including inbreds as well as hybrids. The effects of genetic and environmental conditions on heterogeneity, if any, were limited. Considering that the reproductive tissue of a spike is derived from one primordial cell, it seems that at the start of sexual differentiation there was variation among cells in chromosomal control, which at meiosis determines pairing and crossing-over competence. We suggest that it is an epigenetic system that rigidly maintains this pattern through generative differentiation. In competitive situations the combination most competent for pairing will pair preferentially, forming specific meiotic configurations with different frequencies for different spikes of the same plant. This would explain the heterogeneity between spikes and the homogeneity within spikes. The epigenetic system could involve chromatin conformation or DNA methylation. There were no signs of heterochromatinization.

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Epigenetic Control May Explain Large Within-Plant Heterogeneity of Meiotic Behavior in Telocentric Trisomics of Rye

2008

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“…This plant, which had one 1R and both 3R homologues substituted by their' corresponding two telos (IR heterozygous and 3R homozygous telocentric substitutions, according to Sybenga (1975)), was crossed with one plant of the inbred line E of diploid rye. As described in a previous work (see Benavente and Orellana, 1985), the Chanding pattern of line t is characterized by the presence of conspicuous blocks of constitutive heterochromatin at the telomeres in both normal (metacentric) and telocentric 1R and 3R chromosomes, whereas such C-bands are absent in these chromosomes from the inbred line E (see fig. 1).…”

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confidence: 86%

“…Orellana and Santos (1985) pointed out that mutual influences between both arms should be taken into account when metacentric or submetacentric chromosomes are considered because pairing preferences at a given arm might influence those of the other arm. Moreover, when pairing preferences were analyzed in telotrisomics of rye where three homologous iRS chromosome arms were in competition, an excess of metaphase I associations involving the short arms of the two metacentric partners was found in all plants (Benavente and Orellana, 1985). It was attributed to the high probability for pairing of the long arm (in disomic condition) which could facilitate the progress of synapsis along the chromosome and, consequently, the frequency of pairing between the short arms of metacentric partners would be increased.…”

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confidence: 99%

Pairing competition between metacentric and telocentric chromosomes in autotetraploid rye

Benavente

Orellana

1989

Heredity

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Pairing preferences have been analyzed in tetraploid cells of rye telocentric substitution lines where competition took place between telocentric and metacentric partners within each set. Chromosome arms in telocentric condition (bearing large telomeric blocks of C-heterochromatin) showed a higher probability of being associated at metaphase I. However, the excess of identical over homologous pairing found in most cases could not be ascribed to such differences in pairing (or chiasma formation) ability between homologues. Other hypotheses for explaining preferential pairing in polyploids are discussed.

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Recombination in Sexually Propagated Higher Plants

Friedt

Kaiser

1989

Progress in Botany

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Evidence for preferential pairing in telotrisomic plants of rye

Cited by 4 publications

References 14 publications

Epigenetic Control May Explain Large Within-Plant Heterogeneity of Meiotic Behavior in Telocentric Trisomics of Rye

Epigenetic Control May Explain Large Within-Plant Heterogeneity of Meiotic Behavior in Telocentric Trisomics of Rye

Pairing competition between metacentric and telocentric chromosomes in autotetraploid rye

Recombination in Sexually Propagated Higher Plants

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