Heterochromatin of maize chromosomes: structure and genetic effects

Aguiar-Perecin, Margarida Lopes Rodrigues de; Fluminhan, Antônio; Santos-Serejo, Janay Almeida dos; Gardingo, José Raulindo; Bertão, Mônica Rosa; Decico, Maria Juliana U.; Mondin, Mateus

doi:10.1590/s1415-47572000000400047

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…Breakpoints involved in alterations associated with heterochromatin have been detected in regenerated maize plants [ Lee and Phillips, 1987;Peschke and Phillips, 1992;Aguiar-Perecin et al, 2000;Santos-Serejo and Aguiar-Perecin, 2016]. Breakpoints localized between the heterochromatic knobs and the centromeres have been observed in meiotic studies of regenerated maize plants.…”

confidence: 99%

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Alterations in Heterochromatic Knobs in Maize Callus Culture by Breakage-Fusion-Bridge Cycle and Unequal Crossing Over

Santos-Serejo

Gardingo²,

Mondin³

et al. 2018

Cytogenet Genome Res

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The meiotic and mitotic behavior of regenerated plants derived from a long-term callus culture, designated 12-F, was analyzed. This culture was heterozygous for an amplification of the heterochromatic knob on the long arm of chromosome 7 (K7L). We aimed to investigate if the amplification resulted from a breakage-fusion-bridge (BFB) cycle or from unequal sister chromatid recombination. Therefore, C-banded mitotic metaphases and pachytene, diakinesis, and anaphase I of regenerated plants were analyzed. Additionally, the occurrence of alterations in K7L was investigated in C-banded metaphases from short-term callus cultures derived from lines related to the donor genotype of the 12-F culture. As a result, plants homozygous and heterozygous for the amplification were detected. Meiosis was normal with few abnormalities, such as a low frequency of univalents at diakinesis. In the callus cultures a chromosome 7 with knobs of different sizes in the sister chromatids was detected and interpreted as a result of unequal crossing over. Other chromosomal alterations were consistent with the occurrence of BFB cycles. The finding of unequal crossing over in the cultures supports the conclusion that the amplification in the culture 12-F would be derived from this mechanism. If the amplification was derived from a BFB cycle, the terminal euchromatic segment between knob and the telomere would be deleted, and possibly, homozygous plants would not be viable.

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confidence: 99%

“…In some cytogenetic studies of callus cultures it was shown that chromosome 7 was the most affected in tissue cultures [Fluminhan et al, 1996;Aguiar-Perecin et al, 2000;Santos-Serejo and Aguiar-Perecin, 2016]. In the genotypes studied, this chromosome possessed knobs on the short and long arms and was more prone to rearrangements.…”

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confidence: 95%

Alterations in Heterochromatic Knobs in Maize Callus Culture by Breakage-Fusion-Bridge Cycle and Unequal Crossing Over

Santos-Serejo

Gardingo²,

Mondin³

et al. 2018

Cytogenet Genome Res

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“…Chromosomal breakage and its consequences (deficiencies, duplications, translocations and inversions) are events observed in callus cultures. Breakpoints involved in alterations associated with heterochromatin have been detected in maize regenerated plants (as reviewed by Peschke and Phillips 1992;Aguiar-Perecin et al 2000). Meiotic studies of these plants have shown that most breakpoints were localized between the centromere and the heterochromatic knobs.…”

Section: R a F T Introductionmentioning

confidence: 99%

Breakage–fusion–bridge cycles and de novo telomere formation on broken chromosomes in maize callus cultures

Santos-Serejo

Aguiar-Perecin

2016

Genome

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Breakpoints involved in chromosome alterations associated with heterochromatin have been detected in maize plants regenerated from callus culture. A cytogenetic analysis of plants regenerated from a maize callus was performed aiming to analyze the stability of a chromosome 7 bearing a deficiency-duplication (Df-Dp), which was interpreted as derived from a chromatid type breakage-fusion-bridge (BFB) cycle. The Df-Dp chromosome 7 was stable in mitotic and meiotic cells of the regenerated plants. Fluorescence in situ hybridization showed signals of telomeric sequences on the broken chromosome arm and provided evidence of de novo telomere formation. The stability of two types of altered chromosome 7 was investigated in C-banded metaphases from samples of the original callus that were collected during a period of 30-42 months after culture initiation. New alterations involving heterochromatic knobs of chromosomes 7 and 9 were observed. The aberrant chromosomes were stable in the subcultures, thus providing evidence of broken chromosome healing. The examination of anaphases showed the presence of bridges, which was consistent with the occurrence of BFB cycles. De novo telomere formation occurred in euchromatic and heterochromatic chromosome termini. The results point to events of chromosomal evolution that might occur in plants.

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“…Thus, this type of procedure must be supplemented with an analysis of pachytene stage chromosomes, in which details of chromosomal structure can be visualized. The examination of C-banded metaphases has been useful in some studies, such as those involving the detection of changes in chromosome 7 resulting from breakage or amplification events at knob sites in cells of callus cultures ( Fluminhan et al, 1996 ; Aguiar-Perecin et al, 2000 ). Also, C-banding was used to determine the number of knobs in a work aiming to evaluate the DNA content in maize populations ( Rayburn et al, 1985 ).…”

Section: Introductionmentioning

confidence: 99%

Karyotype variability in tropical maize sister inbred lines and hybrids compared with KYS standard line

et al. 2014

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Maize karyotype variability has been extensively investigated. The identification of maize somatic and pachytene chromosomes has improved with the development of fluorescence in situ hybridization (FISH) using tandemly repeated DNA sequences as probes. We identified the somatic chromosomes of sister inbred lines that were derived from a tropical flint maize population (Jac Duro [JD]), and hybrids between them, using FISH probes for the 180-bp knob repeat, centromeric satellite (CentC), centromeric satellite 4 (Cent4), subtelomeric clone 4-12-1, 5S ribosomal DNA and nucleolus organizing region DNA sequences. The observations were integrated with data based on C-banded mitotic metaphases and conventional analysis of pachytene chromosomes. Heterochromatic knobs visible at pachynema were coincident with C-bands and 180-bp FISH signals on somatic chromosomes, and most of them were large. Variation in the presence of some knobs was observed among lines. Small 180-bp knob signals were invariant on the short arms of chromosomes 1, 6, and 9. The subtelomeric 4-12-1 signal was also invariant and useful for identifying some chromosomes. The centromere location of chromosomes 2 and 4 differed from previous reports on standard maize lines. Somatic chromosomes of a JD line and the commonly used KYS line were compared by FISH in a hybrid of these lines. The pairing behavior of chromosomes 2 and 4 at pachytene stage in this hybrid was investigated using FISH with chromosome-specific probes. The homologues were fully synapsed, including the 5S rDNA and CentC sites on chromosome 2, and Cent4 and subtelomeric 4-12-1 sites on chromosome 4. This suggests that homologous chromosomes could pair through differential degrees of chromatin packaging in homologous arms differing in size. The results contribute to current knowledge of maize global diversity and also raise questions concerning the meiotic pairing of homologous chromosomes possibly differing in their amounts of repetitive DNA.

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Heterochromatin of maize chromosomes: structure and genetic effects

Cited by 8 publications

References 29 publications

Alterations in Heterochromatic Knobs in Maize Callus Culture by Breakage-Fusion-Bridge Cycle and Unequal Crossing Over

Alterations in Heterochromatic Knobs in Maize Callus Culture by Breakage-Fusion-Bridge Cycle and Unequal Crossing Over

Breakage–fusion–bridge cycles and de novo telomere formation on broken chromosomes in maize callus cultures

Karyotype variability in tropical maize sister inbred lines and hybrids compared with KYS standard line

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