Characterization of a maize chromosome 4 centromeric sequence: evidence for an evolutionary relationship with the B chromosome centromere.
Previous work has identified sequences specific to the B chromosome that are a major component of the B centromere. To address the issue of the origin of the B and the evolution of centromere-localized sequences, DNA prepared from plants without B chromosomes was probed to seek evidence for related sequences. Clones were isolated from maize line B73 without B chromosomes by screening DNA at reduced stringency with a B centromeric probe. These clones were localized to maize centromere 4 using fluorescence in situ hybridization. They showed homology to a maize centromere-mapped sequence, to maize B chromosome centromere sequences, and to a portion of the unit repeat of knobs, which act as neocentromeres in maize. A representative copy was used to screen a BAC library to obtain these sequences in a larger context. Each of the six positive BACs obtained was analyzed to determine the nature of centromere 4-specific sequences present. Fifteen subclones of one BAC were sequenced and the organization of this chromosome 4-specific repeat was examined.
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Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA.
Wanous
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MK
Birchler
J A
JA
D001483:Base Sequence; D015139:Blotting, Southern; D002503:Centromere / Q000648:ultrastructure*; D002874:Chromosome Mapping; D002875:Chromosomes / Q000648:ultrastructure*; D022202:Chromosomes, Artificial, Bacterial; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D019992:Databases as Topic; D019143:Evolution, Molecular; D017343:Genes, Plant; D017404:In Situ Hybridization, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D003313:Zea mays / Q000235:genetics*
D004251:DNA Transposable Elements