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Rye Bs disclose ancestral sequences in cereal genomes with a potential role in gametophyte chromatid segregation
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Orientador(es)
Resumo(s)
Two sequence families, E3900 and D1100, are amplified on the subtelomeric domain of the long arm of rye B
chromosomes, the region that controls its drive mechanism. In this work, polymerase chain reaction (PCR) with
a number of primers spanning E3900 shows that the organization and nucleotide sequence of E3900-related portions are
present and highly conserved on rye A chromosomes as well as in other cereals. Quantitative Real-Time PCR estimates
two E3900 sequences to be represented in 100–150 copies on Bs and at least as single copies on As. A novel E3900-
related sequence, with a deletion that results in a frameshift and subsequently an open reading frame with putative DNA
binding motifs, is identified. Expression analysis of E3900 indicates identical transcription levels in leaves from plants
with and without Bs, showing that the expression of these sequences must be silenced on Bs and tightly regulated on As
in leaves. In contrast, E3900 transcription is upregulated during meiosis exclusively in plants with Bs, maintaining a high
level of transcription in the gametophyte. Interestingly, Bs not only influence their own chromatid segregation but also
that of the regular chromosome complement of both rye and wheat. There is a drastic increase in frequency of disrupted
metaphase and anaphase cells in the first mitosis of pollen grains carrying Bs, which appears to be due to anomalous
adherences between sister chromatids. Taken together, this work provides insight into how E3900 sequences are
potentially associated with important evolutionary mechanisms involved in basic cellular processes.
Descrição
Research Article
Palavras-chave
E3900 rye B repeat developmentally regulated transcription chromosome segregation
Contexto Educativo
Citação
"Molecular Biology and Evolution". 26:8 (2009) 1683-1697