Molecular analysis of the structure of the maize B-chromosome

• DOI: 10.1007/bf02254939
• Publication Date: 2005-11-22T20:09:31Z
• Authors: Elizabeth A. Stark; Ian Connerton; Simon T. Bennett; Stephen R. Barnes; John S. Parker; John W. Forster
• Keywords: Repeated sequence; genomic DNA; B chromosome; Bacterial artificial chromosome

The overall composition of the maize B is similar to that of the standard chromosome complement (A-chromosomes). This has been demonstrated by the use of several methods including: (a) genomic in situ hybridization (GISH), (b) analysis of highly repetitive sequences by the comparison of restriction digests of 0B and +B DNA and (c) the characterization of middle-repetitive cloned sequences. By the use of the technique of random amplification of polymorphic DNA-polymerase chain reaction, we have identified a B-specific repetitive sequence family. Sequence analysis of the B-specific clone reveals a relationship to the PREM-1 family of maize retroelements, which are preferentially transcribed in pollen. These results suggest an internal origin of the B-chromosome from within the maize genome, but demonstrate also that specific sequences can evolve by rapid processes of genomic turnover. Models for the origin of the maize B are discussed in the context of the present data.