Incongruent evolution of chromosomal size in rice
Genet. mol. res. (Online)
;
5(2): 373-389, 2006. ilus, tab, graf
Artículo
en Inglés
| LILACS
| ID: lil-442562
ABSTRACT
To investigate genome size evolution, it is usually informative to compare closely related species that vary dramatically in genome size. A whole genome duplication (polyploidy) that occurred in rice (Oryza sativa) about 70 million years ago has been well documented based on current genome sequencing. The presence of three distinct duplicate blocks from the polyploidy, of which one duplicated segment in a block is intact (no sequencing gap) and less than half the length of its syntenic duplicate segment, provided an excellent opportunity for elucidating the causes of their size variation during the post-polyploid time. The results indicated that incongruent patterns (shrunken, balanced and inflated) of chromosomal size evolution occurred in the three duplicate blocks, spanning over 30 Mb among chromosomes 2, 3, 6, 7, and 10, with an average of 20.3% for each. DNA sequences of chromosomes 2 and 3 appeared to had become as short as about half of their initial sequence lengths, chromosomes 6 and 7 had remained basically balanced, and chromosome 10 had become dramatically enlarged (approximately 70%). The size difference between duplicate segments of rice was mainly caused by variations in non-repetitive DNA loss. Amplification of long terminal repeat retrotransposons also played an important role. Moreover, a relationship seems to exist between the chromosomal size differences and the nonhomologous combination in corresponding regions in the rice genome. These findings help shed light on the evolutionary mechanism of genomic sequence variation after polyploidy and genome size evolution.
Texto completo:
Disponible
Índice:
LILACS (Américas)
Asunto principal:
Oryza
/
Genoma de Planta
/
Evolución Molecular
/
Secuencias Repetidas Terminales
/
Cromosomas de las Plantas
Idioma:
Inglés
Revista:
Genet. mol. res. (Online)
Asunto de la revista:
Biologia Molecular
/
Genética
Año:
2006
Tipo del documento:
Artículo
País de afiliación:
China
Institución/País de afiliación:
Zhejiang University/CN
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