A HIGH-DENSITY RICE GENETIC-LINKAGE MAP WITH 2275 MARKERS USING A SINGLE F-2 POPULATION

A 2275-marker genetic map of rice (Oryza sativa L.) covering 1521.6 cM in the Kosambi function has been constructed using 186 F-2 plants fro m a single cross between the japonica variety Nipponbare and the indic a variety Kasalath. The map provides the most detailed and informative genetic map of any plant. Centromere locations on 12 linkage groups w ere determined by dosage analysis of secondary and telotrisomics using >130 DNA markers located on respective chromosome arms. A limited inf luence on meiotic recombination inhibition by the centromere in the ge netic map was discussed. The main sources of the markers in this map w ere expressed sequence tag (EST) clones from Nipponbare callus, root, and shoot libraries. We mapped 1455 loci using ESTs; 615 of these loci showed significant similarities to known, genes, including single-cop y genes, family genes, and isozyme genes. The high-resolution genetic map permitted us to characterize meiotic recombinations in the whole g enome. Positive interference of meiotic recombination was detected bot h by the distribution of recombination number per each chromosome and by the distribution of double crossover interval lengths.