Linkage of allozyme loci in Japanese red pine (Pinus densiflora)

Linkage relationships among 29 polymorphic loci were investigated in Japanese red pine, Pinusdensiflora Sieb. et Zucc. Haploid megagametophytes from 12 highly heterozygous plus-tree clones were used. A total of 217 pairs of two-locus combinations were available for the linkage study. Chi-square and Akaike Information Criterion analyses identified 19 pairs of linkages. Close linkages (r = 0–0.10) were seen for Est-2, 3–Aap-2, 3, Dia-1–Acp, and Shd-1–Got-1. Strong linkages (r = 0.10–0.20) were seen for Est-2, 3–Dia-1, Est-2, 3–Acp, Aap-2, 3–Dia-1, Got-2–Lap-1, and Pgm–Aap-1. Moderate linkages (r = 0.20–0.30) were seen for Adh–Sod, Adh–Pgi-1, 2, Adh–Lap-1, G2d–G6p, and Dia-2–Amy pair of linkages. The remaining six pair combinations, namely 6Pg-1–Est-2, 3, 6Pg-1–Acp, Est-1–Acp, Est-2, 3–Shd-1, Sod–Pgi-1, 2, and Adh–Got-2 were weakly linked (r = 0.30–0.40). In all, 22 loci were classified into five linkage groups by means of three-point mapping methods.