Masatoshi Ubukata

Simultaneous Evaluation of Paternal and Maternal Immigrant Gene Flow and the Implications for the Overall Genetic Composition of Pinus densiflora Dispersed Seeds

When considering the genetic implications of immigrant gene flow, it is important to evaluate both the proportions of immigrant gametes and their genetic composition. We simultaneously investigated paternal and maternal gene flow in dispersed seeds in a natural population of Pinus densiflora located along a ridge. The paternity and maternity of a total of 454 dispersed seeds (in 2004 and 2005) were accurately and separately assigned to 454 candidate adult trees, by analyzing the nuclear DNA of both diploid biparentally derived embryos and haploid maternally derived megagametophytes of the seeds. The relative genetic diversities and differences between within-population and immigrant groups of both paternally and maternally derived gametes (4 groups) that formed the genotypes of the seeds were evaluated. Using 8 microsatellite markers, we found that 64.0-72.6% of paternally derived gametes, and 17.8-20.2% of maternally derived gametes, were from other populations. Principal coordinate analysis showed that the 4 gamete groups tended to be plotted at different locations on the scattergram, indicating that they each have different genetic compositions. Substantial paternal and maternal immigrant gene flow occurred in this population, and therefore, the overall genetic variation of dispersed seeds is enhanced by both paternally and maternally derived immigrant gametes.

Use of different seed tissues for separate biparentage identification of dispersed seeds in conifers: Confirmations and practices for gene flow in Pinus densiflora

To investigate how accurately biparentage assignments for coniferous seeds can be improved by using different kinds of seed tissues, we assigned biparentage to dispersed seeds in a natural stand of Pinus densiflora Siebold & Zucc. (288 mature trees) using two procedures: with or without megagametophyte haplotype data (“MH” and “ordinary” procedures, respectively). Using archived clones, we confirmed the conifer-specific modes of inheritance of three kinds of seed tissues from certain maternal trees using six microsatellite markers. In the natural stand, under the MH procedure, 39.2% of male parents and 77.0% of female parents for a total of 204 seeds analyzed were assigned to at least one mature tree within the study area. At that time, the proportion of exactly matching seeds out of seeds with one matching parent under the MH procedure was significantly larger than that of the seeds under the ordinary procedure. The biparentage assignments under the ordinary procedure corresponded to only 53.7% of the ac...

Microsatellite variation and differentiation among local populations of Castanopsis species in Japan

Microsatellite variations in Castanopsis species in Japan were examined to clarify the genetic relationships among 25 local populations according to the difference in the number of layers of adaxial epidermis in the leaves. Six microsatellite loci were assayed for 629 seedlings from the populations, and these seedlings were classified into five types according to the state of the leaf epidermis. Remarkable differences in the allele frequency of the six microsatellite loci were observed among these local populations. The coefficients of genetic differentiation, RST, of each locus ranged from 0.209 to 0.388. An unweighted pair-group method (UPGMA) phenogram constructed on the population pairwise RST over the loci revealed three clusters (A–C), and six sub-clusters. These clusters reflected the differences in the occurrence frequency of seedlings in each epidermis type within a population. Our findings suggest that clusters A and C are the local populations dominated by Castanopsis sieboldii and Castanopsis cuspidata, respectively, while local populations of cluster B are composed of the two Castanopsis species and/or include many individuals derived by hybridization. The six sub-clusters were found to reflect the geographic relationship among the populations, suggesting a different process for geographic population dynamics during the postglacial period.

Within-crown cone production patterns dependent on cone productivities in Pinus densiflora: effects of vertically differential, pollination-related, cone-growing conditions

Although the variations in within-crown cone production have mainly been associated with resource availability, trees with relatively fewer cones allocate more cones to the optimal vertical layer for cone production than their expected resource availability suggests. We investigated the number of cones (NCone) per branch basal area (BBA) and the proportion of cones (PCone) in the three crown layers (upper, middle, and lower) for 72 Pinus densiflora Sieb. et Zucc. clones in 2004 and 2005. We also measured cone characteristics in each layer to infer their resource or pollen availability. Further, in 2006 we conducted pollination experiments for another 19 P. densiflora ramets, manipulating pollen quality (open-pollinated, self-pollinated (selfed), and polycrossed) in their two crown layers (upper and lower), and examined how pollen quality could affect the among-layer differences. Among 72 clones investigated, PCone in the upper crown layer was significantly greater, with a decrease of the total NCone per B...