Linkage Analysis of Isozyme and Dwarf Loci, and Detection of Lethal Genes in Sugi (Cryptomeria japonica D. Don)

Abstract

In order to obtain basic information for the design of a more detailed linkage map of sugi (Cryptomeria japonica D. Don), 15 isozyme loci with 13 enzyme systems were analyzed for their linkage relationships using crossed families including selfing. Moreover, Iethal genes which led to a deviation of the genotypic segregation ratio, and eventually resultes in abnormal recombination values were analysed. A Iinkage relationship was detected in Mnr : Lap (r= 0.365), and a weak linkage was found in the following 4 pairs of isozyme loci; Shd-2 : 6Pg-1 (r=0.382), 6Pg-2 : Lap (r=0.477), G6p : Pgm-2 (r=0.409), Dia-3 : Est-1 (r =0.293). In the cross of a family of Boka sugi×Kumotooshi, a linkage relationship was observed between the isozyme locus (Shd-1) and dwarf locus(dw-1) with a recombination value of 0.318. The analysis of the abnormal segregation ratio in isozyme loci, revealed the presence of 5 Iethal genes (including embryonic lethal genes). In particular, the lethal genes were strongly linked to G6p, Dia-3 and Lap.