Chiasma Frequency Is Region Specific and Chromosome Conformation Dependent in a Rye Chromosome Added to Wheat

Naranjo, T.; Valenzuela, Nohelia; Perera, Esther

doi:10.1159/000314029

Cited by 22 publications

(32 citation statements)

References 140 publications

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“…Deletion of all but the proximal 30% of the long arm of rye chromosome 5 resulted in loss of COs in the remaining region (72). However, chromosome pairing and synapsis in the deleted arm appeared normal.…”

Section: Chiasma Localization In Members Of the Grass Familymentioning

confidence: 98%

Factors Underlying Restricted Crossover Localization in Barley Meiosis

et al. 2014

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Meiotic recombination results in the formation of cytological structures known as chiasmata at the sites of genetic crossovers (COs). The formation of at least one chiasma/CO between homologous chromosome pairs is essential for accurate chromosome segregation at the first meiotic division as well as for generating genetic variation. Although DNA double-strand breaks, which initiate recombination, are widely distributed along the chromosomes, this is not necessarily reflected in the chiasma distribution. In many species there is a tendency for chiasmata to be distributed in favored regions along the chromosomes, whereas in others, such as barley and some other grasses, chiasma localization is extremely pronounced. Localization of chiasma to the distal regions of barley chromosomes restricts the genetic variation available to breeders. Studies reviewed herein are beginning to provide an explanation for chiasma localization in barley. Moreover, they suggest a potential route to manipulating chiasma distribution that could be of value to plant breeders.

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Section: Chiasma Localization In Members Of the Grass Familymentioning

confidence: 98%

Factors Underlying Restricted Crossover Localization in Barley Meiosis

et al. 2014

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“…In a wheat-rye translocation line (1R inv ), the long arm was inverted for most of its length and chiasmata were observed to be proximal to the centromere (Lukaszewski, 2008). Naranjo et al (2010) studied the meiotic behavior of a rye chromosome pair 5R with a terminal deletion (del5R) in a wheat background having only the proximal 30% of the long arm. Synapsis of the deficient chromosome arm pair del5RL was completed in most meiocytes at pachytene but the number of chiasmata formed was much lower than in the intact 5RL arm (Naranjo et al, 2010).…”

Section: Chiasmata Predominantly Occur In Distal Euchromatin-rich Dnamentioning

confidence: 99%

“…Naranjo et al (2010) studied the meiotic behavior of a rye chromosome pair 5R with a terminal deletion (del5R) in a wheat background having only the proximal 30% of the long arm. Synapsis of the deficient chromosome arm pair del5RL was completed in most meiocytes at pachytene but the number of chiasmata formed was much lower than in the intact 5RL arm (Naranjo et al, 2010). This led the authors from both studies to conclude that there was an apparent division of the chromosome arms, which were either receptive or unreceptive to chiasma formation.…”

Section: Chiasmata Predominantly Occur In Distal Euchromatin-rich Dnamentioning

confidence: 99%

Spatiotemporal Asymmetry of the Meiotic Program Underlies the Predominantly Distal Distribution of Meiotic Crossovers in Barley

et al. 2012

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Meiosis involves reciprocal exchange of genetic information between homologous chromosomes to generate new allelic combinations. In cereals, the distribution of genetic crossovers, cytologically visible as chiasmata, is skewed toward the distal regions of the chromosomes. However, many genes are known to lie within interstitial/proximal regions of low recombination, creating a limitation for breeders. We investigated the factors underlying the pattern of chiasma formation in barley (Hordeum vulgare) and show that chiasma distribution reflects polarization in the spatiotemporal initiation of recombination, chromosome pairing, and synapsis. Consequently, meiotic progression in distal chromosomal regions occurs in coordination with the chromatin cycles that are a conserved feature of the meiotic program. Recombination initiation in interstitial and proximal regions occurs later than distal events, is not coordinated with the cycles, and rarely progresses to form chiasmata. Early recombination initiation is spatially associated with early replicating, euchromatic DNA, which is predominately found in distal regions. We demonstrate that a modest temperature shift is sufficient to alter meiotic progression in relation to the chromosome cycles. The polarization of the meiotic processes is reduced and is accompanied by a shift in chiasma distribution with an increase in interstitial and proximal chiasmata, suggesting a potential route to modify recombination in cereals.

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“…A fourth DNA probe, pUCM600, containing a rye-specific repeat [González-García et al, 2011] was added for the quantification of the level of synapsis in cells at middle zygotene, late zygotene and pachytene. Probe pAtT4 labels both wheat and rye telomeres and was used to identify the prophase I stage as previously described Naranjo et al, 2010]. Rye chromosome arms associated at metaphase I were identified using probes pUCM600, pAWRC.1, and pSc74.…”

Section: Fluorescence In Situ Hybridizationmentioning

confidence: 99%

“…There is a modified chromosome 5R (del5R) with a metacentric conformation resulting from a large deletion produced in the long arm. The short arm (5RS) is the same in both chromosome conformations, but its telomere is included more frequently in the telomere cluster in the metacentric than in the submetacentric conformation [Naranjo et al, 2010].…”

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confidence: 99%

Dynamics of Rye Telomeres in a Wheat Background during Early Meiosis

Naranjo

2014

Cytogenet Genome Res

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Migration of the telomere of the short arm of rye chromosome 5R (5RS) during bouquet organization is dependent on the conformation that this chromosome adopts in its intact, submetacentric, or truncated, metacentric, form. In order to establish whether the telomere migration dependence on chromosome conformation is a common feature of all rye chromosomes, the behavior of the telomeres of 2 other rye chromosomes, 1R and 6R, with apparent differences in the arm ratio, has been studied at the bouquet stage and compared with that of 5R. The presence of subtelomeric heterochromatic chromomeres in both arms of 1R and 6R, which were visualized by FISH, revealed the position of the adjacent telomeres in the bouquet. While the end of the long arms of both chromosomes was, with some exceptions, always included in the telomere cluster, the end of the short arms failed to migrate to the telomere pole. Disturbed telomere migration was more often observed in the short arm of the submetacentric chromosome 6R than in the short arm of the almost metacentric chromosome 1R. Thus, the chromosomal conformation effect on telomere mobility is a common feature of all rye chromosomes. Incomplete telomere clustering is followed by failure of synapsis and chiasma formation in chromosomes 5R and 6R. Chromosome arm 1RS, which carries the NOR, completes synapsis earlier than 5RS or 6RS, facilitated by the nucleolar fusion that occurs during early zygotene.

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Chiasma Frequency Is Region Specific and Chromosome Conformation Dependent in a Rye Chromosome Added to Wheat

Cited by 22 publications

References 140 publications

Factors Underlying Restricted Crossover Localization in Barley Meiosis

Factors Underlying Restricted Crossover Localization in Barley Meiosis

Spatiotemporal Asymmetry of the Meiotic Program Underlies the Predominantly Distal Distribution of Meiotic Crossovers in Barley

Dynamics of Rye Telomeres in a Wheat Background during Early Meiosis

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