Robinia pseudoacacia L. is a clonal tree species. To investigate a mutation within eight microsatellite loci of R. pseudoacacia, we analyzed DNA samples obtained from different leaf samples within each ramet, leaves from ramets within the genet, and seeds. Of the eight loci, locus Rops15 (AG motif) displayed hypermutability. The mutation rates of Rops15 within each ramet, among ramets within the genet, and offspring were 6.27% (ranging from 0 to 31.1%), 6.11% (from 0 to 25.0%) and 3.78% (from 0 to 10.9%), respectively. The mutation rate increased with allele size (13-71 repeat units). The mutation patterns observed in Rops15 were distinctive in two ways. First, there was a significant bias toward additions over deletions, and both addition and deletion of single repeats were dominant at alleles with lengths less than 232 bp (63 repeats). Second, for the longest allele of 248 bp (71 repeats), the number of losses was higher than the number of gains. These observations suggest that the mutation patterns of microsatellites in R. pseudoacacia may follow a generalized stepwise mutation model, and that the tendency of long alleles to mutate to shorter lengths acts to prevent infinite growth. Finally, the observation of somatic hypermutability at locus Rops15 highlights the need for caution when using highly polymorphic microsatellites for population genetic structure and paternity analysis in tree species.

The effects of the application of controlled-release fertilizer on the growth and ectomycorrhizal colonization of pot-grown seedlings of the dipterocarp species Dryobalanops lanceolata were studied in a nursery in Sarawak, Malaysia, to produce a sufficient number of healthy dipterocarp seedlings to reforest degraded tropical lands. Samples of a forest soil were mixed with an equal volume of river sand following a typical practice in the Niah Forest Research Station nursery. About 1.4 kg of the soil mixture was placed in plastic bags. Either a 700-day (80% elution of the ingredients at 20degreesC) controlled-release fertilizer (CRF, N : P : K = 12 : 14: 12) or a chemical fertilizer (CF, N : P : K = 15 : 15 : 15) was applied at the rate of 2, 5, and 10 g per pot. After 16 months of cultivation, mycorrhizal colonization and photosynthetic activity of the seedlings were evaluated, and the nutrient concentration and dry mass were analyzed. Application of ten grams of CRF resulted in the enhancement of the biomass, leaf development, photosynthetic activity, nutrient status, and ectomycorrhizal formation of the seedlings. It is expected that the CRF treatment can be used practically for dipterocarp seedling production in tropical nurseries.

Microsatellite analysis was used to investigate the patch establishment and development of Polygonum cuspidatum Sieb. et Zucc, a clonal herbaceous plant that dominates the primary succession on the southeast slope of Mount Fuji. Genotypes of P. cuspidatum in 155 patches at the study site differed from each other. This indicates that P. cuspidatum patches are initially established by seed dispersed on the bare scoria field, and not by clonal rhizome extension. Genetic differentiation was estimated using the FST values between subpopulations at the study site. There was almost no genetic differentiation between subpopulations, indicating the presence of massive gene flow. The pollen fathers of seeds and maternal genets of current-year seedlings were inferred from the microsatellite allele composition by a simple exclusion method. The wide, random distribution of pollen fathers suggests that pollen dispersal occurs over a broad area. Maternal analysis showed a tendency for seed dispersal to be biased to the area nearby and down slope from the mother plants. Patch establishment under massive gene flow may result from such pollen and seed dispersal. To understand the process of patch development, aerial photographs taken from 1962 to 1999 were compared, and then genets in each of 36 patches were identified from the microsatellite genotypes of P. cuspidatum shoots. The comparison of aerial photographs showed that most of the patches enlarged each year and that some neighbouring patches combined during growth. Genet analysis demonstrated a high correlation between patch area and the area of the largest genet within it, and that new genets were recruited at the patch periphery. These findings indicate that both vegetative and sexual reproduction, i.e. rhizome extension and the establishment of new seedlings, contribute to the development of P. cuspidatum patches.

The early stage of volcanic desert succession is underway on the southeastern slope of Mount Fuji. We used markers of nuclear microsatellites (simple sequence repeats; SSR) and chloroplast microsatellites (cpSSR) to investigate the population genetic structure and reproduction dynamics of Salix reinii , one of the dominant pioneer shrubs in this area. The number of S . reinii genets in a patch and the area of the largest genet within the patch increased with patch area, suggesting that both clonal growth and seedling recruitment are involved in the reproduction dynamics of S . reinii . Five polymorphic cpSSR markers were developed for S . reinii by sequencing the noncoding regions between universal sequences in the chloroplast genome. Nineteen different cpSSR haplotypes were identified, indicating that S . reinii pioneer genets were created by the long-distance dispersal of seeds originating from different mother genets around the study site, where all vegetation was destroyed during the last eruption. Furthermore, the clustered distributions of different haplotypes within each patch or plot suggested that newly colonized genets tended to be generated from seeds dispersed near the initially established mother genets. These results revealed that the establishment of the S . reinii population on the southeastern slope of Mount Fuji involved two sequential modes of seed dispersal: long-distance dispersal followed by short-distance dispersal.

Salix reinii Franch. et Savat., a crawl shrub, is one of the most dominant pioneer trees on the southeastern slope of Mt. Fuji, on which an early stage of the volcanic desert succession has been underway since the last eruption in 1707. To investigate the population genetic structure within and among patches of S. reinii, seven polymorphic microsatellite markers were developed by an enrichment procedure. The multiple banding patterns amplified by developed microsatellite markers showed the polyploidy in S. reinii growing on the southeastern slope of Mt. Fuji.