Dynamics of Rye Telomeres in a Wheat Background during Early Meiosis

Naranjo, T.

doi:10.1159/000363524

Cited by 15 publications

(25 citation statements)

References 29 publications

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“…Unsuccessful telomere migration is followed of failure of synapsis and recombination of these arms (Naranjo et al 2010;Naranjo 2014). This behavior may be mediated by the heterobraquial conformation of chromosome 5B.…”

Section: Discussionmentioning

confidence: 99%

Forcing the shift of the crossover site to proximal regions in wheat chromosomes

Naranjo

2015

Theor Appl Genet

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Terminal deletions obligate the first crossover to be formed in more proximal positions. This increases the recombination rate in intercalary intervals but not in the proximity of the centromere. Crossovers are not uniformly distributed along chromosomes in wheat. They take place preferentially in distal positions. The effect of the chromosomal architecture on crossover positioning has been analyzed from the chiasmate bonds at metaphase I formed by the truncated arms of 51 terminal deletion lines of eight wheat chromosomes. Chromosome 4A and the B genome chromosomes, in their standard or truncated conformation, and their arms, were identified by C-banding. Chromosomes studied show a similar chiasma distribution. Reduction of the size of the truncated arms is accompanied by a gradual decrease of the chiasma frequency in chromosome arms 1BL, 3BS, 3BL, 4BL, 5BS, 5BL, 6BL, 7BS, 7BL and 4AL. In chromosome arm 1BS, most chiasmata are concentrated in the distal half of the satellite and, in 4AS, in the distal 24 %. The arms 2BS, 2BL and 6BS do not show a simple decreasing gradient of the recombination rate, the chiasma frequency increases in subdistal intervals compared to more distal regions. Although terminal deletions usually induce an increase of chiasma frequency in intercalary regions, the level of intact chromosome arms is maintained in only a few deletion lines. Truncated arms containing only the 20 % proximal of the intact arm do not form chiasmata. The relationships of chiasma positioning with chromatin structure and genome organization is discussed.

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Section: Discussionmentioning

confidence: 99%

Forcing the shift of the crossover site to proximal regions in wheat chromosomes

Naranjo

2015

Theor Appl Genet

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“…The mechanism of reduced chromosome pairing in allopolyploids is also not fully understood. In wheat-rye hybrids, a relationship between the behavior of telomeres and the success of chromosome pairing has been observed by Naranjo (2014), who reported that reduced pairing of rye chromosomes in wheat appeared to be a consequence of disturbed migration of rye telomeres into the leptotene bouquet. We have observed that the problem of aberrant rye telomeres is not limited to the initial stages of meiosis but may be systemic in nature.…”

Section: Chromosome Pairing In Hybridsmentioning

confidence: 88%

Competition of Parental Genomes in Plant Hybrids

et al. 2020

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Interspecific hybridization represents one of the main mechanisms of plant speciation. Merging of two genomes from different subspecies, species, or even genera is frequently accompanied by whole-genome duplication (WGD). Besides its evolutionary role, interspecific hybridization has also been successfully implemented in multiple breeding programs. Interspecific hybrids combine agronomic traits of two crop species or can be used to introgress specific loci of interests, such as those for resistance against abiotic or biotic stresses. The genomes of newly established interspecific hybrids (both allopolyploids and homoploids) undergo dramatic changes, including chromosome rearrangements, amplifications of tandem repeats, activation of mobile repetitive elements, and gene expression modifications. To ensure genome stability and proper transmission of chromosomes from both parental genomes into subsequent generations, allopolyploids often evolve mechanisms regulating chromosome pairing. Such regulatory systems allow only pairing of homologous chromosomes and hamper pairing of homoeologs. Despite such regulatory systems, several hybrid examples with frequent homoeologous chromosome pairing have been reported. These reports open a way for the replacement of one parental genome by the other. In this review, we provide an overview of the current knowledge of genomic changes in interspecific homoploid and allopolyploid hybrids, with strictly homologous pairing and with relaxed pairing of homoeologs.

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“…This led to the elimination of rye chromosomes. This was most probably a consequence of disturbed migration of rye telomeres into the leptotene bouquet [24] as an extension of their erratic behavior in somatic tissues [25].…”

Section: Discussionmentioning

confidence: 99%

Selective Elimination of Parental Chromatin from Introgression Cultivars of xFestulolium (Festuca × Lolium)

et al. 2019

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Alien chromosome introgressions can be used to introduce beneficial traits from one species into another. However, exploitation of the introgressions in breeding requires proper transmission of introgressed segments to consecutive generations. In xFestulolium hybrids chromosomes of Festuca and Lolium readily pair and recombine. This opens a way for introgression of traits (e.g., abiotic and biotic stress resistance) from Festuca into elite Lolium cultivars. However, retention of Festuca chromatin in xFestulolium is uncertain as several studies indicated its gradual elimination over generations of sexual reproduction. Here we investigated genome composition in two subsequent generations of four introgression xFestulolium (F. pratensis × L. multiflorum) cultivars using genomic in situ hybridization. We observed about 27–32% elimination of Festuca chromatin in a single round of multiplication. At this pace, Festuca chromatin would be completely eliminated in about four generations of seed multiplication. On the other hand, we observed that it is possible to increase the proportion of Festuca chromatin in the cultivars by proper selection of mating plants. Nevertheless, once selection is relaxed, the first round of the seed multiplication reverts the genome composition back to the Lolium type. Thus, it seems that amphiploid forms of xFestulolium with relatively stable hybrid genomes may be more promising material for future breeding than introgression lines.

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Dynamics of Rye Telomeres in a Wheat Background during Early Meiosis

Cited by 15 publications

References 29 publications

Forcing the shift of the crossover site to proximal regions in wheat chromosomes

Forcing the shift of the crossover site to proximal regions in wheat chromosomes

Competition of Parental Genomes in Plant Hybrids

Selective Elimination of Parental Chromatin from Introgression Cultivars of xFestulolium (Festuca × Lolium)

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