An improved technique for isolating codominant compound microsatellite markers

Chloroplast DNA sequencing and detailed microsatellite genotyping of all remnant populations suggests that only a single genet survives of the critically endangered plant Rehmannia japonica

Rehmannia japonica (Thunb.) Makino ex T. Yamaz. is an endangered perennial herb species in Japan. Although earlier the Japanese considered it a variety of R. glutinosa, recent Japanese taxonomists have consistently regarded it as an independent species. According to the historical literature, Rehmannia japonica seems to have been known in China and Japan in the past. However, Chinese taxonomists do not recognize R. japonica at present. In Japan, only two populations are known, and although these populations flower every year, seed reproduction has not been observed. In this study, we aimed to reveal the phylogenetic relationships and levels of genetic diversity of R. japonica. A haplotype network based on two chloroplast DNA regions (trnL-trnF and rps16) showed that the sequences of R. japonica were distinguishable by three or four sites of indels from the most closely related species, R. chingii, consistent with the separate species status of R. japonica. An analysis of genetic diversity using twelve microsatellite loci showed that all of the ramets of R. japonica collected from two geographically isolated populations had an identical multilocus genotype, including identical heterozygous genotypes at six loci. This result indicated asexual origin of all sampled ramets. This study also suggests that the absence of sexual reproduction of R. japonica is explained by self-incompatibility combined with only a single genet remaining in the R. japonica populations.

The Relationship between Mating System and Genetic Diversity in Diploid Sexual Populations of Cyrtomium falcatum in Japan

The impact of variation in mating system on genetic diversity is a well-debated topic in evolutionary biology. The diploid sexual race of Cyrtomium falcatum (Japanese holly fern) shows mating system variation, i.e., it displays two different types of sexual expression (gametangia formation) in gametophytes: mixed (M) type and separate (S) type. We examined whether there is variation in the selfing rate among populations of this species, and evaluated the relationship between mating system, genetic diversity and effective population size using microsatellites. In this study, we developed eight new microsatellite markers and evaluated genetic diversity and structure of seven populations (four M-type and three S-type). Past effective population sizes (Ne) were inferred using Approximate Bayesian computation (ABC). The values of fixation index (F_IS), allelic richness (A_R) and gene diversity (h) differed significantly between the M-type (F_IS: 0.626, A_R: 1.999, h: 0.152) and the S-type (F_IS: 0.208, A_R: 2.718, h: 0.367) populations (when admixed individuals were removed from two populations). Although evidence of past bottleneck events was detected in all populations by ABC, the current N_e of the M-type populations was about a third of that of the S-type populations. These results suggest that the M-type populations have experienced more frequent bottlenecks, which could be related to their higher colonization ability via gametophytic selfing. Although high population differentiation among populations was detected (F_ST = 0.581, F’_ST = 0.739), there was no clear genetic differentiation between the M- and S-types. Instead, significant isolation by distance was detected among all populations. These results suggest that mating system variation in this species is generated by the selection for single spore colonization during local extinction and recolonization events and there is no genetic structure due to mating system.

Microsatellite markers for the critically endangered elm species Ulmus gaussenii (Ulmaceae)

The Anhui elm Ulmus gaussenii is listed as a critically endangered species by the International Union for Conservation of Nature and is endemic to China, where its only population is restricted to Langya Mountain in Chuzhou, Anhui Province. To better understand the population genetics of U. gaussenii, we developed 12 microsatellite markers using an improved technique. The 12 markers were polymorphic, with the number of alleles per locus ranging from two to nine. Observed and expected heterozygosities ranged from 0.021 to 0.750 and 0.225 to 0.744, respectively. The inbreeding coefficient ranged from -0.157 to 0.960. Significant linkage disequilibrium was detected for two pairs of loci, and significant deviations from Hardy-Weinberg equilibrium were found in nine loci. These microsatellite markers will contribute to the studies of population genetics in U. gaussenii, which in turn will contribute to species conservation and protection.

Predominance of a single clone of the most widely distributed bamboo species Phyllostachys edulis in East Asia

Phyllostachys edulis, one of the most dominant bamboo species with the leptomorph rhizome system, has been asexually expanding its range into adjacent natural forest sites by shooting new culms. The resulting ecological problems include simplification of stand structure and decline in the species diversity of local flora. In this study, the genetic diversity of P. edulis for the entire distribution range from Japan to China was analyzed using 16 microsatellite markers. Among these, 12 loci were fixed by a single allele, whereas only two alleles were detected for each of the remaining 4 loci; all adult samples shared the same genotype at all loci including the four heterozygous loci. These observations indicate that all current samples from Japan and China comprise an identical clone. The clone is distributed over more than 2,800 km with an estimated biomass of approximately 6.6 × 10(11) kg, which is exceptionally large. Among seedlings from flowering events in 2005 and 2006, 20 different genets were generated by recombination through selfing of a single flowering genet. Predominance of a single clone in the wild and a diverse composition of genets among seedlings suggest that the intermittent flowering of P. edulis in the wild has produced a variety of clones through recombination. However, the resulting seedlings cannot compete with other tree species or adult P. edulis, and almost all adult P. edulis growing in Japan and China likely propagated through vegetative reproduction of a single clone by human transplantation, and subsequently expanded into adjacent forest sites by shooting young sprouts. The relatively small size of the flowering area and rapid culm reproduction has led to the stability of P. edulis communities. However, the low genetic diversity is an important consideration for the long-term management of this prevailing bamboo species.

Molecular phylogeography and ecological niche modelling of a widespread herbaceous climber, Tetrastigma hemsleyanum (Vitaceae): insights into Plio-Pleistocene range dynamics of evergreen forest in subtropical China

Warm-temperate evergreen (WTE) forest represents the typical vegetation type of subtropical China, but how its component species responded to past environmental change remains largely unknown. Here, we reconstruct the evolutionary history of Tetrastigma hemsleyanum, an herbaceous climber restricted to the WTE forest. Twenty populations were genotyped using chloroplast DNA sequences and nuclear microsatellite loci to assess population structure and diversity, supplemented by phylogenetic dating, ancestral area reconstructions and ecological niche modeling (ENM) of the species distributions during the Last Glacial Maximum (LGM) and at present. Lineages in Southwest vs Central-South-East China diverged through climate/tectonic-induced vicariance of an ancestral southern range during the early Pliocene. Long-term stability in the Southwest contrasts with latitudinal range shifts in the Central-South-East region during the early-to-mid-Pleistocene. Genetic and ENM data strongly suggest refugial persistence in situ at the LGM. Pre-Quaternary environmental changes appear to have had a persistent influence on the population genetic structure of this subtropical WTE forest species. Our findings suggest relative demographic stability of this biome in China over the last glacial-interglacial cycle, in contrast with palaeobiome reconstructions showing that this forest biome retreated to areas of today's tropical South China during the LGM.

Development of polymorphic microsatellite loci in the perennial herb Hepatica nobilis var. japonica (Ranunculaceae)

PREMISE OF THE STUDY

Microsatellite markers were developed and characterized in the vulnerable plant Hepatica nobilis var. japonica (Ranunculaceae) to investigate its genetic diversity, population structure, and gene flow.

METHODS AND RESULTS

Fourteen microsatellite markers were developed. The number of alleles per locus ranged from one to 12, and the expected heterozygosity per locus ranged from 0.043 to 0.855. Eleven markers were successfully amplified in the cultivar 'Mego' from Japan.

CONCLUSIONS

These microsatellite markers can be used to investigate the genetic diversity, population structure, and gene flow of H. nobilis var. japonica.

Development and characterization of polymorphic microsatellite markers (SSRs) for an endemic plant, Pseudolarix amabilis (Nelson) Rehd. (Pinaceae)

Pseudolarix (Pinaceae) is a vulnerable (sensu IUCN) monotypic genus restricted to southeastern China. To better understand levels of genetic diversity, population structure and gene flow among populations of P. amabilis, we developed five compound SSR markers and ten novel polymorphic expressed sequence tags (EST) derived microsatellites. The results showed that all 15 loci were polymorphic with the number of alleles per locus ranging from two to seven. The expected and observed heterozygosities varied from 0.169 to 0.752, and 0.000 to 1.000, respectively. The inbreeding coefficient ranged from −0.833 to 1.000. These markers will contribute to research on genetic diversity and population genetic structure of P. amabilis, which in turn will contribute to the species conservation.

Development and characterization of microsatellite markers in sawih tree (Duabanga moluccana Blume) using ISSR-suppression PCR techniques

Duabanga moluccana (or locally known as sawih) is an indigenous fast growing tropical tree species that confers various advantages for the timber industry and for planted forests development. In this paper, we isolated and characterized 8 polymorphic microsatellite markers from the D. moluccana genome using ISSR-suppression PCR techniques. The number of alleles and PIC values ranged from 3 to 8 alleles per locus and from 0.488 to 0.792, respectively. Three microsatellite loci were deviated from Hardy-Weinberg equilibrium (P < 0.05). The transferability rate ranged from 24 to 100 % among the three indigenous tree species tested. This indicates that the newly developed microsatellite markers would be useful tools for population genetic studies on D. moluccana and other indigenous tree species.

Isolation and characterization of microsatellite loci in Fimbristylis sericea (Cyperaceae)(1.)

PREMISE OF THE STUDY

We developed microsatellite markers for Fimbristylis sericea, a coastal herb found in sand dunes in Asia and Australia. •

METHODS AND RESULTS

Twelve microsatellite loci were isolated, and the genetic variability within and among local populations was characterized. The number of alleles per locus was two to five with a mean of 3.5, total expected heterozygosity per locus was 0.069-0.645 with a mean of 0.336, and average expected heterozygosity within a population per locus was 0.051-0.230. Most of the loci deviated significantly from Hardy-Weinberg equilibrium. •

CONCLUSIONS

All 12 microsatellite loci were polymorphic within and among populations. These loci could be useful genetic markers for population genetic studies of F. sericea populations.

Development of microsatellite markers for Vitex rotundifolia (Verbenaceae), an endangered coastal plant in Lake Biwa, Japan

PREMISE OF THE STUDY

Microsatellite loci were developed for Vitex rotundifolia, an endangered species isolated to Lake Biwa, to investigate its genetic diversity and population structure. •

METHODS AND RESULTS

Ten primer sets were identified in Japanese populations of V. rotundifolia. The number of alleles per locus ranged from one to six and gene diversity per locus ranged from 0.040 to 0.697 between two populations. In addition, all loci could be successfully amplified in V. trifolia. •

CONCLUSIONS

These markers will be useful for studies of genetic diversity and population structure of endangered species isolated to Lake Biwa of V. rotundifolia, to aid in the development of conservation strategies.

Development of microsatellite loci in Scrophularia incisa (Scrophulariaceae) and cross-amplification in congeneric species

PREMISE OF THE STUDY

To elucidate the population genetics and phylogeography of Scrophularia incisa, microsatellite primers were developed. We also applied these microsatellite markers to its closely related species S. dentata and S. kiriloviana. •

METHODS AND RESULTS

Using the compound microsatellite marker technique, 12 microsatellite primers were identified in S. incisa. The number of alleles ranged from 14 to 26 when assessed in 78 individuals from four populations. With high cross-species transferability, these primers also amplified in S. dentata and S. kiriloviana. •

CONCLUSIONS

These results indicate that these microsatellite markers are adequate for detecting and characterizing population genetic structure in the Chinese species of sect. Tomiophyllum at fine and range-wide geographical scales.

Development of SSR markers for the tropical alpine tree species Leptospermum recurvum (Myrtaceae) on Mount Kinabalu in Borneo

PREMISE OF THE STUDY

Nuclear microsatellite (simple sequence repeat [SSR]) markers were developed for the woody species Leptospermum recurvum found on Mount Kinabalu, Borneo, to facilitate investigation of the genetic structure and patterns of gene flow in relation to leaf phenotypic polymorphisms. •

METHODS AND RESULTS

Eleven primer pairs were developed using the compound SSR marker technique. Ten of the 11 loci were polymorphic and their expected heterozygosity ranged from 0.04 to 0.83. Neither linkage disequilibrium nor departure from Hardy-Weinberg equilibrium were detected. All primer pairs also amplified the SSR loci of L. polygalifolium. •

CONCLUSIONS

These findings suggest the utility of these primers for investigating genetic structure and gene flow in L. recurvum and indicate their applicability to another species of Leptospermum.

Development and characterization of microsatellite markers for Lilium longiflorum (Liliaceae)

PREMISE OF THE STUDY

Ten microsatellite primers were developed to obtain information on genetic variation in Lilium longiflorum, a bulbous species showing high intraspecific genetic differentiation. •

METHODS AND RESULTS

Of 61 microsatellite loci isolated using the dual suppression PCR technique, 10 loci were effective to characterize and estimate genetic variation in two populations of L. longiflorum. The number of alleles at each locus was different between the populations (averages = 3.2 and 10.3 alleles per locus), and the mean observed heterozygosity values were 0.245 and 0.732. •

CONCLUSIONS

Our results demonstrate that there is significant genetic variation between the populations and that the microsatellite markers developed in this study will be useful tools for the investigation of the genetic structure and mating system of natural L. longiflorum populations.

PERMANENT GENETIC RESOURCES: Development of microsatellite markers for two nonviviparous mangrove species, Acanthus ilicifolius and Lumnitzera racemosa

Eight and nine of microsatellite loci were isolated from two nonviviparous mangrove species, Acanthus ilicifolius and Lumnitzera racemosa, respectively. The number of alleles per locus ranged from two to eight in A. ilicifolius and two to nine in L. racemosa. The observed heterozygosities ranged from 0.200 to 0.875 in A. ilicifolius and from 0.025 to 0.350 in L. racemosa. These loci would be effective for analysing genetic diversity and population genetic structure of these two mangrove species.

Microsatellite loci isolated from the scleractinian coral, Acropora nobilis

We report the isolation and characterization of eight microsatellite loci from the scleractinian coral, Acropora nobilis. The microsatellite loci were obtained using compound SSR primers or an enrichment protocol. All the loci were polymorphic with four to eight alleles per locus and observed heterozygosities ranging from 0.22 to 0.76. Some of the primers developed for the two congeners, Acropora palmata and Acropora millepora were applicable to A. nobilis. These loci are useful for studying the connectivity among A. nobilis populations in Okinawa, southern Japan.

Isolation and characterization of 20 polymorphic microsatellite markers for Juglans mandshurica (Juglandaceae)

PREMISE OF THE STUDY

Fifty microsatellite loci were developed for the endangered species Juglans mandshurica to investigate its genetic diversity and population structure. •

METHODS AND RESULTS

In all, 50 microsatellite markers were isolated from J. mandshurica, using the Fast Isolation by AFLP of Sequences COntaining repeats (FIASCO) protocol. Twenty of these polymorphic markers were assessed in samples collected from 98 individuals among five populations in northeastern China. Across all of the J. mandshurica samples, the number of alleles per locus ranged from one to 17. •

CONCLUSIONS

These new microsatellite loci will be useful for conservation genetics studies of J. mandshurica.

The Complete Plastid Genome Sequence of Madagascar Periwinkle Catharanthus roseus (L.) G. Don: Plastid Genome Evolution, Molecular Marker Identification, and Phylogenetic Implications in Asterids

The Madagascar periwinkle (Catharanthusroseus in the family Apocynaceae) is an important medicinal plant and is the source of several widely marketed chemotherapeutic drugs. It is also commonly grown for its ornamental values and, due to ease of infection and distinctiveness of symptoms, is often used as the host for studies on phytoplasmas, an important group of uncultivated plant pathogens. To gain insights into the characteristics of apocynaceous plastid genomes (plastomes), we used a reference-assisted approach to assemble the complete plastome of C. roseus, which could be applied to other C. roseus-related studies. The C. roseus plastome is the second completely sequenced plastome in the asterid order Gentianales. We performed comparative analyses with two other representative sequences in the same order, including the complete plastome of Coffeaarabica (from the basal Gentianales family Rubiaceae) and the nearly complete plastome of Asclepiassyriaca (Apocynaceae). The results demonstrated considerable variations in gene content and plastome organization within Apocynaceae, including the presence/absence of three essential genes (i.e., accD, clpP, and ycf1) and large size changes in non-coding regions (e.g., rps2-rpoC2 and IRb-ndhF). To find plastome markers of potential utility for Catharanthus breeding and phylogenetic analyses, we identified 41 C. roseus-specific simple sequence repeats. Furthermore, five intergenic regions with high divergence between C. roseus and three other euasterids I taxa were identified as candidate markers. To resolve the euasterids I interordinal relationships, 82 plastome genes were used for phylogenetic inference. With the addition of representatives from Apocynaceae and sampling of most other asterid orders, a sister relationship between Gentianales and Solanales is supported.

Development of 10 novel polymorphic microsatellite markers for the Indo-Pacific horned starfish, Protoreaster nodosus

Ten novel polymorphic nuclear microsatellite simple sequence repeat (SSR) markers were isolated from an Indo-Pacific horned starfish, Protoreaster nodosus. The isolated SSR markers provided polymorphisms of 2-9 alleles per locus in three populations obtained from Indonesia and the Philippines. The expected and observed heterozygosities ranged from 0.049 to 0.691 and from 0.050 to 0.800, respectively. Pairwise FST values among three populations ranged from 0.018 to 0.050 (global FST=0.031). All P. nodosus individuals collected from three populations exhibited different genotypes for the ten identified SSR markers, indicating that P. nodosus reproduces sexually. Then the developed SSR markers will be useful for studying the population and conservation genetics of P. nodosus.

New microsatellite markers for Tricyrtis macrantha (Convallariaceae) and cross-amplification in closely related species

PREMISE OF THE STUDY

Microsatellite markers were characterized in Tricyrtis macrantha (sect. Brachycyrtis, Convallariaceae), a vulnerable species endemic to Japan, to investigate its genetic diversity and population structure. •

METHODS AND RESULTS

Eleven microsatellite markers were developed. The number of alleles per locus ranged from one to seven, and genetic diversity per locus ranged from 0.142 to 0.812. Four markers were successfully amplified in other species of sect. Brachycyrtis (T. ishiiana, T. ishiiana var. surugensis, and T. macranthopsis). •

CONCLUSIONS

The microsatellite markers can be used to investigate the genetic diversity and population structure of the vulnerable and endangered species of Tricyrtis sect. Brachycyrtis, to aid in the development of conservation strategies for each species.

Isolation and characterization of microsatellite markers for Canavalia cathartica and C. lineata (Fabaceae)

PREMISE OF THE STUDY

Microsatellite markers were developed for the sea-dispersed legume Canavalia cathartica to investigate its genetic diversity and population structure. We also applied these microsatellite markers to the closely related species C. lineata. •

METHODS AND RESULTS

Ten primer sets were developed for C. cathartica, and all of the primers were amplified in C. lineata. The number of alleles per locus ranged from two to 13 and one to 10 for C. cathartica and C. lineata, respectively. The expected heterozygosity ranged from 0.375 to 0.870 and from 0.071 to 0.877 for C. cathartica and C. lineata, respectively. •

CONCLUSIONS

The 10 microsatellite markers developed in this study can be used to analyze the population genetic structure of C. cathartica and other related taxa.

Isolation and characterization of polymorphic microsatellite markers from the Chinese medicinal herb Atractylodes macrocephala (Asteraceae)

Atractylodes macrocephala Koidz. (Asteraceae) is an economically important Chinese medicinal herb. In this study, 15 polymorphic microsatellite markers were developed from A. macrocephala using the compound microsatellite marker technique. Levels of polymorphism within the 15 markers were assessed using 83 individuals from two wild and two cultivated populations in China. The number of alleles per locus ranged from 2 to 20, with an average of 9.9 alleles. Observed and expected heterozygosities ranged from 0.083 to 1.000 and from 0.097 to 0.938, respectively. These markers will be valuable for germplasm classification and identification, as well as for assessing the genetic diversity and spatial genetic structure among wild and cultivated populations of A. macrocephala.

Isolation and characterization of 13 novel polymorphic microsatellite markers for Pinus koraiensis (Pinaceae)

PREMISE OF THE STUDY

Thirteen polymorphic microsatellite markers were developed to investigate the genetic diversity and population structure of Pinus koraiensis. •

METHODS AND RESULTS

Using the Fast Isolation by AFLP of Sequences COntaining repeats (FIASCO) method with three specific PCR primers for screening the positive clones, 13 loci were found to be polymorphic in 78 individuals of P. koraiensis. Across all of the P. koraiensis samples, the number of alleles per locus ranged from two to 11. •

CONCLUSIONS

These polymorphic markers will be useful for conservation genetics studies of this species and to inform the development of effective P. koraiensis conservation programs.

Development of 12 microsatellite markers for Platycrater arguta (Hydrangeaceae) endemic to East Asia

PREMISE OF THE STUDY

Microsatellite markers were characterized in Platycrater arguta, a rare endemic shrub from eastern China and southern Japan, to investigate its population genetic structure, phylogeographic patterns, and breeding system.

METHODS AND RESULTS

Using both the Fast Isolation by AFLP of Sequences COntaining repeats (FIASCO) protocol and the compound microsatellite marker technique, we developed 12 microsatellite markers. All primers showed polymorphism when assessed in 43 individuals from two populations in eastern China and southern Japan. Overall, the number of alleles ranged from five to 21, with an average of 14.91 alleles per locus.

CONCLUSIONS

These markers can be used in further studies on population genetics, phylogeography, and breeding system of P. arguta.

Development of microsatellite markers for the dove tree, Davidia involucrata (Nyssaceae), a rare endemic from China

PREMISE OF THE STUDY

Microsatellite primers were developed for the endangered Davidia involucrata to assess the population genetics and infer its evolutionary history.

METHODS AND RESULTS

Using both the modified magnetic bead hybridization method and the dual-suppression PCR method, we isolated and characterized 12 polymorphic microsatellite loci using 134 individuals from five populations in southwestern China. The number of alleles per locus ranged from six to 21 (mean = 10.8). The expected heterozygosity per locus ranged from 0.404 to 0.918 and observed heterozygosity ranged from 0.015 to 0.821.

CONCLUSIONS

All of the 12 microsatellite markers developed for D. involucrata are polymorphic, and lay a solid foundation for further studies of the population genetics of this famous tree.

Development and characterization of microsatellite markers for Emmenopterys henryi (Rubiaceae), a rare tree from China

PREMISE OF THE STUDY

Compound microsatellite primers were developed for Emmenopterys henryi, an endangered deciduous tree endemic to China, to assess its genetic diversity and population structure as well as its evolutionary history.

METHODS AND RESULTS

Using the compound microsatellite marker technique, 10 pairs of polymorphic microsatellite primers were isolated and characterized in E. henryi. Levels of polymorphism were tested across a total of 63 individuals from three natural populations. Allele numbers varied from 10 to 20 per locus, with an average of 14.50 alleles per locus. The observed heterozygosity per locus ranged from 0.125 to 0.962, and the expected heterozygosity ranged from 0.377 to 0.903.

CONCLUSIONS

The highly polymorphic markers developed and characterized in this study will facilitate evolutionary and population genetic studies in E. henryi.

Microsatellites reveal a strong subdivision of genetic structure in Chinese populations of the mite Tetranychus urticae Koch (Acari: Tetranychidae)

BACKGROUND

Two colour forms of the two-spotted spider mite (Tetranychus urticae Koch) coexist in China: a red (carmine) form, which is considered to be native and a green form which is considered to be invasive. The population genetic diversity and population genetic structure of this organism were unclear in China, and there is a controversy over whether they constitute distinct species. To address these issues, we genotyped a total of 1,055 individuals from 18 red populations and 7 green populations in China using eight microsatellite loci.

RESULTS

We identified 109 alleles. We found a highly significant genetic differentiation among the 25 populations (global FST = 0.506, global FST {ENA} = 0.473) and a low genetic diversity in each population. In addition, genetic diversity of the red form mites was found to be higher than the green form. Pearson correlations between statistics of variation (AR and HE) and geographic coordinates (latitude and longitude) showed that the genetic diversity of the red form was correlated with latitude. Using Bayesian clustering, we divided the Chinese mite populations into five clades which were well congruent with their geographic distributions.

CONCLUSIONS

Spider mites possess low levels of genetic diversity, limit gene flow between populations and significant and IBD (isolation by distance) effect. These factors in turn contribute to the strong subdivision of genetic structure. In addition, population genetic structure results don't support the separation of the two forms of spider mite into two species. The morphological differences between the two forms of mites may be a result of epigenetic effects.

Isolation and characterization of polymorphic microsatellite loci from the invasive plant Solidago canadensis (Asteraceae)

Solidago canadensis, a clonal herb originally from North America (common name: Canada goldenrod), is an invasive species in many countries. We developed microsatellite primers for this species. Eleven polymorphic loci were generated and primers were designed. Polymorphism of these 11 loci was assessed in 35 plants from two populations (Wuhan and Shanghai) in China. The number of alleles per locus ranged from 3 to 14. The observed and expected heterozygosities varied from 0.0732 to 0.7391 and from 0.1177 to 0.8687, respectively. These microsatellite markers will be useful tools for studies of population genetics in the native and invasive range of this species.

Development of microsatellite markers in heterostylous Hedyotis chrysotricha (Rubiaceae)

PREMISE OF THE STUDY

Microsatellite primers were developed for a heterostylous herb, Hedyotis chrysotricha to investigate the effect of habitat fragmentation on its genetic diversity and population structure.

METHODS AND RESULTS

Twelve primer sets were developed and their polymorphisms were tested on 47 individuals from two island populations of H. chrysotricha in Thousand Island Lake of China. The number of alleles per locus ranged from five to 10, with an average of seven alleles. Expected heterozygosity per locus ranged from 0.284 to 0.821 and observed heterozygosity ranged from 0.191 to 0.851.

CONCLUSIONS

We showed that all of the 12 microsatellite markers developed for H. chrysotricha are polymorphic within populations, which should provide a powerful tool for assessing population structure and genetic diversity across fragmented and continuous populations, and for studying the genetic effects of habitat fragmentation on this species.

Narrowing Down the Mapping of Plant Sex-Determination Regions Using New Y-Chromosome-Specific Markers and Heavy-Ion Beam Irradiation-Induced Y-Deletion Mutants in Silene latifolia

Silene latifolia is a well-studied model system for plant XY sex determination. Three maleness factors are thought to function on the Y chromosome, gynoecium suppression factor (GSF), stamen-promoting factor (SPF), and male fertility factor (MFF), and their deletions result in hermaphrodites, anther defects, and pollen defects, respectively. Although a framework map of the Y chromosome exists, the sex determination genes have not been identified, and no markers close enough to potentially be used for BAC library screening are yet available. The analysis of Y deletion mutants by Y-chromosome-specific STS markers is an efficient way to isolate sex determination regions, but more Y-specific STS markers are needed to accelerate the exploration of sex determination factors. Herein, we report a marker design method that uses simple sequence repeats, which is especially effective on the Y chromosome of S. latifolia because it contains many simple sequence repeats. Six new Y-chromosome-specific STS markers were obtained, SmicSy1–6. These were used to detect relatively small Y deletion sites in heavy-ion beam irradiation-induced mutants. The mapping of male sex determination regions was narrowed down by using more markers and smaller-sized Y deletion mutants. One new marker, SmicSy6, is a proximal marker to SPF and, thus, a second index for SPF. The region including SPF is thought to be located between two SPF proximal markers. The flower phenotype correlates with the deletion size of SPF using SPF proximal markers. These findings represent new progress in isolating the sex determination factor, which has been studied for more than 50 years.

Isolation of compound microsatellite markers in Begonia fenicis (Begoniaceae) endemic to East and Southeast Asian islands

PREMISE OF THE STUDY

We developed compound microsatellite markers for Begonia fenicis, a species endemic to eastern and southeastern Asian islands, to investigate geographical genetic structure.

METHODS AND RESULTS

Using the compound microsatellite marker technique, 21 markers were developed and six polymorphic markers were characterized for samples from four islands in Taiwan and southern Japan. The number of alleles per locus ranged from two to six (mean = 4.33). Observed and expected heterozygosities were 0.125-0.725 (0.383) and 0.498-0.719 (0.641), and polymorphic information content was 0.371-0.664 (0.567). The interspecific transferability of the 21 markers was evaluated for eight species of the section Diploclinium from the Philippines; 15 markers were successfully amplified in one to eight species.

CONCLUSIONS

These results indicate the utility of the six microsatellite markers in B. fenicis to investigate geographical genetic structure. The transferable markers are potentially useful for other species of the section.

Development of microsatellite markers for Cinnamomum camphora (Lauraceae)

PREMISE OF THE STUDY

Cinnamomum camphora is an evergreen tree distributed in southern Japan, Taiwan, and southeastern China. Because of its vast utilization and cultivation, the natural distribution area of this species has been controversial.

METHODS AND RESULTS

I isolated and characterized 22 microsatellite loci in C. camphora. Levels of polymorphism were evaluated in 104 adult trees from three populations in Japan: Meiji Jingu (Shinto Shrine), Kajiya Plantation, and Manazuru Peninsula. The mean number of alleles per locus ranged from 4.1 to 8.0 among populations. The mean observed and expected heterozygosities per population ranged from 0.53 to 0.60 and 0.55 to 0.68, respectively.

CONCLUSIONS

All of 22 loci showed a clear and strong single band for each allele, and revealed a useful degree of polymorphism. The microsatellite markers described here will be useful to study the history, population dynamics, mating system, and genetic structure of C. camphora.

Genetic diversity of the Japanese wood pigeon, Columba janthina, endemic to islands of East Asia, estimated by newly developed microsatellite markers

The Japanese wood pigeon Columba janthina is endemic to islands of East Asia and is listed as Near Threatened by the International Union for Conservation of Nature (IUCN). One subspecies, C. janthina nitens, in particular, is at the greatest risk of extinction due to its small population size. To reduce the extinction risk of C. janthina, it is important to understand the species' present genetic status and to develop an appropriate conservation plan based on genetic data. We developed seven new microsatellite markers for two subspecies of C. janthina: C. janthina janthina and C. janthina nitens. We also confirmed the cross-use of one microsatellite marker developed for Columba livia var. domestica. Seven loci were polymorphic in C. janthina janthina, while two loci were polymorphic in C. janthina nitens. Using the markers, we performed preliminary analysis of genetic diversity and genetic structure within each subspecies. The expected heterozygosity ranged from 0.00 to 0.64 in C. janthina janthina and from 0.00 to 0.08 in C. janthina nitens. Each subspecies and each population within C. janthina janthina had different allele frequencies. C. janthina nitens exhibited far lower genetic diversity than C. janthina janthina. Furthermore, C. janthina nitens appears to have experienced strong genetic drift from a common ancestral population, inferred by STRUCTURE analysis. The markers described here may be useful for investigating genetic diversity and genetic structure of C. janthina populations, and could be used to estimate appropriate evolutionary significant unit and to guide development of a captive breeding program based on genetic information.

Isolation and characterization of microsatellite loci in a clonal herb, Cardamine leucantha (Brassicaceae)

PREMISE OF THE STUDY

Microsatellite markers were developed to analyze the clonal diversity and population genetic structure of a clonal plant, Cardamine leucantha.

METHODS AND RESULTS

Microsatellite loci were isolated by using compound simple sequence repeat (SSR) primers, resulting in 25 pairs including 14 useful markers. Samples from 33, 20, and 17 ramets in three populations were identified as belonging to 23, 18, and 17 genotypic individuals, respectively.

CONCLUSIONS

These SSR markers will be used for identifying genets and evaluating genetic diversity of the clonal plant C. leucantha.