Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Poster: Maize, Sorghum, Millet, Sugarcane, and related
We have achieved a major technological advance towards the development of a cytogenetic map for maize (Zea mays). The use of a maize chromosome-addition line of oat, OMAd9.2 (Kynast et al., 2001; Plant Physiol. 125:1216), provides a distinct advantage for obtaining clear images of optically-isolated chromosomes using a chromosome spread and painting technique. We designed a direct-labeled oligonucleotide FISH probe, MCCY (Maize CentC labeled with Cy5), to detect the centromere. The MCCY probe reproducibly hybridizes to a small discrete region in the centromere of maize-9 ( Koumbaris and Bass, 2002; Maize Newsletter, vol.76). Using 3D deconvolution microscopy and computer-assisted image analysis, we verified that the maize-9 arm ratio (Long/Short; 1.6 to 2.1 from prior studies) is preserved in the oat genome background (1.7 in our system). Next we have determined the cytogenetic map position for three test case core bin marker loci; CBM901 (Core Bin Marker 9.01, umc109), CBM902 (9.02, bz1), and CBM908 (9.08, csu54b). Marker-selected sorghum BAC clones were identified by library hybridization screening, purified, and labeled for FISH. We detected FISH signals at 9S-0.8, 9S-0.65, and 9L-0.9 for CBM901, CBM902, and CBM908. These positions are consistent with their distributions within the linkage map. This work represents a major breakthrough for locating genes and integrating maps. We obtained results with the first three loci tested and therefore believe that this approach may prove reliable for many other loci, enabling the development of a detailed cytogenetic map for the maize genome.