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標題: Cytomolecular characterization and origin of de novo formed maize B chromosome variants
作者: Cheng, Ya-Ming
Feng, Ying-Ru
Lin, Yao-Pin
Peng, Shu-Fen
關鍵字: B chromosome
Cell Line
Chromosomes, Plant
Genetic Markers
In Situ Hybridization, Fluorescence
Interspersed Repetitive Sequences
Zea mays
Genetic Variation
Physical Chromosome Mapping
摘要: B chromosomes are dispensable elements that occur in many species, including maize. The maize B chromosome is acrocentric and highly heterochromatic and undergoes nondisjunction during the second pollen mitosis. In this study, we determined the genetic behavior and organization of two naturally occurring B chromosome variants (designated B(ta) and B(tb)). The morphology and genetic behavior of the B(ta) chromosome were similar to those of the typical B chromosome, but the B(ta) chromosome contained a deletion in the first heterochromatin region and had higher transmission frequencies through both male and female parents. The B(tb) chromosome was reduced in size, consisted primarily of heterochromatin, and had a lower transmission frequency. The B(tb) chromosome lacked nondisjunctional behavior, which was restored by the presence of normal B chromosomes in the cell. Furthermore, the B(tb) chromosome contained two centromeric regions, only one of which was active. The organization of these two naturally occurring B chromosome variants was also determined using fluorescence in situ hybridization with B-associated sequences and by amplification of B-specific molecular markers to create possible evolutionary models.
Appears in Collections:農藝學系



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