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

Autor(es)

Santos-Serejo, Janay A. ; Aguiar-Perecin, Margarida L. R.

• Tipo de documento: Artigo Científico
• Fonte: GENOME; v. 59, n. 6, p. 12-pg., 2016-06-01.

Resumo

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. (AU)

• Processo FAPESP: 99/01640-4 - Mapeamento por hibridacao "in situ" (fish) de sequencias repetitivas de dna, em tandem e dispersas, em linhagens e somaclones de milho e analise do dna genomico (gish) em poliploides de cratalaria.
• Beneficiário: Janay Almeida dos Santos Serejo
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 98/01170-5 - Análise da organização do genoma de alguns grupos de plantas através de técnicas de hibridação molecular in situ para mapeamento de sequências repetitivas de DNA (FISH) e análise de DNA genômico (GISH)
• Beneficiário: Margarida Lopes Rodrigues de Aguiar-Perecin
• Modalidade de apoio: Auxílio à Pesquisa - Temático