title: Characterization of four B-chromosome-specific RAPDs and the development of SCAR markers on the maize B-chromosome.
abstract: Understanding the molecular organization of the maize B-chromosome is hindered by its high homology with A-chromosomes. Recently, various approaches have been employed to overcome this hindrance, and several B-chromosome-specific sequences have been identified. Here, we cloned and characterized four previously published B-chromosome-specific RAPD fragments in detail. The results of sequence analysis, Southern hybridization and fluorescence in situ hybridization revealed that the four RAPD fragments are repetitive and present on both the B- and A-chromosomes, which supports an A-chromosome origin of the B-chromosome. We further developed four sequence-characterized amplified region (SCAR) markers derived from the four B-chromosome-specific RAPDs. These markers amplified PCR products exclusively in plants with B-chromosomes and were further mapped to definite distal heterochromatic regions of the B-chromosome by 15 B-A translocations. Furthermore, reverse transcriptase-PCR revealed that two of the four B-chromosome-specific RAPD fragments are transcriptionally active. These results demonstrate the feasibility of using B-chromosome-specific RAPD sequences to generate SCAR markers specific to the B-chromosome and might apply to other sequences of the maize B-chromosome.
authors.affiliation: Department of Agronomy, National Chung Hsing University, 250 Kuo Kuang Road, Taichung, 402, Taiwan.
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Kao
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Lin
authors.forename: Shu-Fen
authors.initials: SF
authors.lastname: Peng
authors.forename: Ya-Ming
authors.initials: YM
authors.lastname: Cheng
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics*; D017343:Genes, Plant; D005819:Genetic Markers; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D019105:Random Amplified Polymorphic DNA Technique; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D014178:Translocation, Genetic; D003313:Zea mays / Q000235:genetics*
chemical_list: D005819:Genetic Markers