Investigation on the factors for depression of propagation ability in an isolated beech population-Analysis of the loci for inbreeding depression maintained within a meta-population-

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Self and cross pollination were performed with a mother tree grown in a natural population of Fagus crenata. Although the percentages of sound acorns produced by self pollination were remarkably low (0 to 16.2%), those produced by cross pollination were higher and varied with the pollen parent (41 to 95%). The results suggest Fagus crenata is self-incompatible.Genotypes of the parental trees and F_1 progenies were determined by AFLP and SSR markers, and linkage maps for male (140 markers,12 linkage groups,1037 cM) and female (206 markers,13 linkage groups,1096 cM) were constructed. The acorn-soundness for cross pollination was correlated with the genome wide similarities between mother and the pollen parents, indicating the existence of bi-parental inbreeding depression. To examine the number and repertories of the alleles related to inbreeding depression, segregation distortion in F_1 progenies generated from the pollination with the different fathers was examined at the 87 loci selected from whole genome.Fifteen loci represented significant segregation distortion. In the three loci, segregation distortion was observed in common with two pedigrees. In the five loci, segregation distortion was observed in common with three different pedigrees. These results indicate that the individuals grown in the local population shared alleles related to inbreeding depressionPollen mediated gene flow was assessed using four SSR markers. The majority (92%) of pollen mediated gene flow was revealed to be limited within the local population. Although beech shows self incompatibility and has some loci related to inbreeding depression and the week spatial genetic structure was formed within the local population, correlation between relatedness and pollen parent-contribution was very week. Since distances between the parents, as well as the size of pollen parents affected on the paternal contribution, pollen productivity might be important factor for acorn productivity.