Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Development Of Chromosome-Specific Markers And Integration Of Genetic Map To Chromosome Map In Brassica campestris

Ki-Byung Lim¹ , Jung-Sun Kim¹ , Hans J De Jong² , Tae-Jin Yang¹ , MyungHo Lim¹ , Soo-Jin Kwon¹ , Jin-A Kim¹ , Mina Jin¹ , Yong-Pyo Lim³ , Dal-Hoe Koo³ , Jae-Wook Bang³ , Ho-Il Kim¹ , Beom-Seok Park¹

¹  Brassica Genomics Team, National Institute of Agricultural Biotechnology (NIAB), RDA, Suwon, 441-707 Korea

²  Laboratory of Genetics, Wageningen University, The Netherlands

³  Chungnam National University, Daejeon, Korea

A molecular cytogenetic map of Brassica campestris (2n = 2x = 20) was constructed on the basis of a pachytene DAPI karyogram. The exact positions of heterochromatin blocks of each chromosome were characterized by employment of bleached DAPI staining method. Large pericentromeric hetrochromatin occupying up to 50% of all the chromosomes consist two types of major centromeric repeats such as CentBr1 and CentBr2, and (peri)centromere specific retrotransposons, centromeric retrotransposon, gypsy type, of Brassica (CRgBr) and centromeric retrotransposon, copia type, of Brassica (CRcBr). CentBr1 and 2 are considered to be major elements for the centromeric heterochromatin in Chinese cabbage. The CRgBr occupy especially large blocks of chromosome 1, 3 and 5 and the CRcBr appears in most pericentromeric heterochromatins of all chromosomes. We describe a mitotic metaphase and pachytene karyogram in which all chromosomes can be identified based on chromosome length, centromere position, heterochromatin patterns, and the positions of repetitive sequences visualized by FISH. Furthermore, we identified at least two chromosome-specific BAC clones for each chromosome (chromosome 1 to 10) that correspond to 10 linkage groups of genetic map. The relative positions of the chromosome-specific BACs and repetitive sequences on the pachytene chromosomes were identified between genetic and cytological distances of markers. The integration of genetic and cytogenetic maps by FISH pachytene karyotype analysis represents unequivocal identification of B. campestris chromosomes.