Supporting research on making linkage maps of marker, RFLP and RAPD loci in genome of sugi, Cryptomeria japonica D.Don

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Sugi, Cryptomeria japonica D.Don has been a important forestry species in Japan sice old times. It has haploid chromosome number of 11 with similar phenotypic features except to two chromosomes which have a satelite or secondary constriction.In this project, firstly, studies were made on the methods for estimatin of recombination values between marker loci including isozyme, RFLP and RAPD loci with or without the presence of a lethal factor. Existence of a lethal locus was examined by the magnitude of deviation of the observed segregation ratio from expected one for each locus separately. The fitness of the model involving a lethal factor were evaluated by LOD scores. This method was applied for isozyme segregation and it was found a lethal gene linked to Lap, G6p, Dia-3 respectively.In a three generation progeny derived from a cross of Kumotooshi and Okinoyama sugi, 164 loci including 128 RFLP,33 RAPD,2 isozyme and 1 dwarf were put in a linkage map with 13 linkage groups with total map distance of 1,190 cM.Out of 13 linkage groups, there were 8 linkage groups which had clustered loci with deviated segregation ratios. One or two lethal genes were detected in 6 linkage groups, and it was found that with the lethal genes, map distances were elongated than those estimated by free of lethal gene. Another map in which 175 RAPD loci were placed, was made by analysis of haploid megagametophytes. It had 14 linkage groups with 2,212.3 cM in total.Discrimination of haploid chromosome was tried by clod treatment and fluorescence in situ hybridization. It was tried to improve the methods and chromosome fragments were recovered after cutting with laser beam.