Features of B. rapa chromosome A3. (a) Mitotic metaphase structure of chromosome A3 with FISH signals of 45S (red), 5S (green) rDNAs, and CentBr2 (magenta). (b) Image of DAPI-stained pachytene spread of chromosome A3 showing the heterochromatic NORs of the short arm (bright blue) and euchromatic long arm (blue). (c) VCS (cv. VC1 x cv. SR5) genetic map showing the positions of the BAC clones found nearest the end of each contig. (d) Physical map showing the location of nine sequence contigs (blue). The chromosome is roughly 34.2 Mb long, spans a genetic map distance of 140.7 cM with 243 kb/cM, and contains 6.4% of the unique sequence of the B. rapa genome. The centromere is shown as a pink circle, the NOR of the rDNA repeat region in the short arm is represented as a brown bar, and telomeres are light blue. The telomere, centromere, and NOR are not drown to scale. The sizes of eight unsequenced gaps measured by pachytene FISH are given in kilobases. Red areas in (b, d) point to the position of the hybridization signal of KBrH34P23 in sequence contig 8.