Comparative chromosome painting using the At4-b BAC contig in amhidiploid Brassica juncea and its two parental species. (a,b) Three copies of the At4-b contig in pachytene chromosome complements of B. rapa (AA genome, homeologs R1–R4) and B. nigra (BB genome, homeologs N1–N3). (c) Six chromosome regions homeologous to the At4-b contig in B. juncea (AABB genome). Two B. rapa-derived homeologs (R2 and R3) showed a structure deviating from that of B. rapa likely because of a translocation (R2) and an inversion (R3), respectively. Chromosomes were counterstained with DAPI. Diagrams were drawn to scale (according to measured regions labeled by a bar on the right) for the corresponding species. Blue arrows in diagrams indicate assumed inversions; brown bracket-like lines depict complex rearrangements. The enumeration of homeologs does not refer to linkage groups of the corresponding species. Scale, 5 μm.
