Chromosomal arm-specific bacterial artificial chromosome (BAC) markers and rice chromosome identification. (A) The morphology and DAPI-staining patterns of the 12 rice pachytene bivalents were identified by hybridization to the 12 short-arm-specific BAC clones (green arrowheads; clone names are listed in Table 1), centromere-specific probe pRCS2 (yellow arrowheads), and the 12 long-arm-specific BAC clones (red arrowheads). The three probes on each pachytene bivalent were sequentially probed on the same pachytene cells. Grey-scale images of the FISH signals were pseudocolored as green, yellow, and red, respectively, and merged with the chromosomal image. (B) A somatic metaphase cell of rice primary trisomic 11 (2n = 24 + 11S·11L) probed with BAC a0071H11 that is specific to the long arm of rice chromosome 11. FISH signals are observed on three chromosomes. Bar, 5 μm. (C) Interphase nuclei from root tip cells of rice primary trisomic 11 hybridized to BAC a0071H11. Three hybridization spots are observed in each nucleus, indicating three copies of chromosome 11 in this plant. Bar, 10 μm. (D) A somatic metaphase cell of a variant derived from a primary trisomic 11 plant probed with the 11S-specific BAC a0040B10 (green signals), 11L-specific BAC a0071H11 (yellow signals), and centromere-specific clone pRCS2 (red signals). This plant contains one normal chromosome 11 (11S·11L), one telocentric chromosome derived from the long arm of 11 (11L·), and one isochromosome derived from the short arm of 11 (11S·11S). Image process is the same as that in Fig. 1A. Bar, 5 μm.
