Isolation and Characterization of Novel Microsatellite Markers in Pomegranate (Punica granatum L.)

Pomegranate (Punica granatum L.) has been cultivated from ancient times for its economic, ornamental and medicinal properties globally. Here, we report the isolation and characterization of 12 polymorphic microsatellite markers from a repeat-enriched genomic library of Punica granatum L. The genetic diversity of these loci was assessed in 60 genotypes of Punica granatum L. All loci were variable: the number of polymorphic alleles per locus ranged from two to five (average 2.9). The observed and expected heterozygosities ranged from 0.15 to 0.87 and 0.29 to 0.65, respectively. The polymorphic information content ranged from 0.26 to 0.61 (average: 0.43). To the best of our knowledge, this is the first time that polymorphic microsatellite markers have been reported for P. granatum L. These new markers should allow studies of the population structure and genetic diversity of pomegranate to be performed in the future.     

Development and Characterization of Novel Microsatellite Markers for the Peach Fruit Moth Carposina sasakii (Lepidoptera: Carposinidae) Using Next-Generation Sequencing

The peach fruit moth Carposina sasakii is an economically important pest on dozens of fruits from Rosaceae and Rhamnaceae in Northeast Asia. We developed novel microsatellite markers for C. sasakii from randomly sequenced regions of the genome using next-generation sequencing. In total, 95,153 microsatellite markers were isolated from 4.70 GB genomic sequences. Thirty-five polymorphic markers were developed by assessing in 63 individuals from two geographical populations. The allele numbers ranged from 2 to 9 with an average value of 4.60 per locus, while the polymorphism information content ranged from 0.075 to 0.696 with an average value of 0.407. Furthermore, the observed and expected heterozygosity varied from 0.000 to 0.677 and 0.062 to 0.771, respectively. The microsatellites developed provide abundant molecular markers for investigating genetic structure, genetic diversity, and existence of host-plant associated biotypes of C. sasakii.     

Isolation and Characterization of New 24 Microsatellite DNA Markers for Golden Cuttlefish (Sepia esculenta)

Twenty-four microsatellite DNA markers were isolated and characterized for golden cuttlefish (Sepia esculenta) from a (GT)(13)-enriched genomic library. Loci were tested in 48 individuals from Jiaozhou bay of China. The numbers of alleles per locus ranged from two to 25 with an average of 10.3. The observed and expected heterozygosities ranged from 0.063 to 0.896 and from 0.137 to 0.953, with averages of 0.519 and 0.633, respectively. Six loci significantly deviated from Hardy-Weinberg equilibrium after Bonferroni's correction and no significant linkage disequilibrium between loci pairs was detected. These microsatellite markers would be useful for analyzing the population genetic structure to make conservation and management decisions for S. esculenta.     

Large-Scale Isolation of Microsatellites from Chinese Mitten Crab Eriocheir sinensis via a Solexa Genomic Survey

Microsatellites are simple sequence repeats with a high degree of polymorphism in the genome; they are used as DNA markers in many molecular genetic studies. Using traditional methods such as the magnetic beads enrichment method, only a few microsatellite markers have been isolated from the Chinese mitten crab Eriocheir sinensis, as the crab genome sequence information is unavailable. Here, we have identified a large number of microsatellites from the Chinese mitten crab by taking advantage of Solexa genomic surveying. A total of 141,737 SSR (simple sequence repeats) motifs were identified via analysis of 883 Mb of the crab genomic DNA information, including mono-, di-, tri-, tetra-, penta- and hexa-nucleotide repeat motifs. The number of di-nucleotide repeat motifs was 82,979, making this the most abundant type of repeat motif (58.54%); the second most abundant were the tri-nucleotide repeats (42,657, 30.11%). Among di-nucleotide repeats, the most frequent repeats were AC motifs, accounting for 67.55% of the total number. AGG motifs were the most frequent (59.32%) of the tri-nucleotide motifs. A total of 15,125 microsatellite loci had a flanking sequence suitable for setting the primer of a polymerase chain reaction (PCR). To verify the identified SSRs, a subset of 100 primer pairs was randomly selected for PCR. Eighty two primer sets (82%) produced strong PCR products matching expected sizes, and 78% were polymorphic. In an analysis of 30 wild individuals from the Yangtze River with 20 primer sets, the number of alleles per locus ranged from 2–14 and the mean allelic richness was 7.4. No linkage disequilibrium was found between any pair of loci, indicating that the markers were independent. The Hardy-Weinberg equilibrium test showed significant deviation in four of the 20 microsatellite loci after sequential Bonferroni corrections. This method is cost- and time-effective in comparison to traditional approaches for the isolation of microsatellites.     

A Molecular Genetic Linkage Map of Eucommia ulmoides and Quantitative Trait Loci (QTL) Analysis for Growth Traits

Eucommia ulmoides is an economically important tree species for both herbal medicine and organic chemical industry. Effort to breed varieties with improved yield and quality is limited by the lack of knowledge on the genetic basis of the traits. A genetic linkage map of E. ulmoides was constructed from a full-sib family using sequence-related amplified polymorphism, amplified fragment length polymorphism, inter-simple sequence repeat and simple sequence repeat markers. In total, 706 markers were mapped in 25 linkage groups covering 2133 cM. The genetic linkage map covered approximately 89% of the estimated E. ulmoides genome with an average of 3.1 cM between adjacent markers. The present genetic linkage map was used to identify quantitative trait loci (QTL) affecting growth-related traits. Eighteen QTLs were found to explain 12.4%–33.3% of the phenotypic variance. This genetic linkage map provides a tool for marker-assisted selection and for studies of genome in E. ulmoides.     

Comparison between Wild and Hatchery Populations of Korean Pen Shell (Atrina pectinata) Using Microsatellite DNA Markers

Pen shell (Atrina pectinata) is a popular food source with a high commercial value in a number of Asian Pacific areas. The natural A. pectinata population has been declining continuously over the past several decades. Microsatellite DNA markers are a useful DNA-based tool for monitoring the genetic variation of pen shell populations. In this study, 20 polymorphic microsatellite (MS) DNA markers were identified from a partial genomic pen shell DNA library enriched in CA repeats, and used to compare allelic variation between wild and hatchery pen shell populations in Korea. A total of 438 alleles were detected at the 20 MS loci in the two populations. All loci were easily amplified and demonstrated allelic variability, with the number of alleles ranging from 5 to 35 in the wild population and from 5 to 22 in the farmed population. The average observed and expected heterozygosities were 0.69 and 0.82, respectively, in the hatchery samples and 0.69 and 0.83, respectively, in the wild samples. Statistical analysis of fixation index (F(ST)) and analysis of molecular variance (AMOVA) showed minor, but significant, genetic differences between the wild and hatchery populations (F(ST) = 0.0106, CI(95%) = 0.003-0.017). These microsatellite loci may be valuable for future aquaculture and population genetic studies for developing conservation and management plans. Further studies with additional pen shell samples are needed to conclusively determine the genetic diversity between the wild and hatchery populations.     

Application of Novel Polymorphic Microsatellite Loci Identified in the Korean Pacific Abalone (Haliotis diversicolor supertexta (Haliotidae)) in the Genetic Characterization of Wild and Released Populations

The small abalone, Haliotis diversicolor supertexta, of the family Haliotidae, is one of the most important species of marine shellfish in eastern Asia. Over the past few decades, this species has drastically declined in Korea. Thus, hatchery-bred seeds have been released into natural coastal areas to compensate for the reduced fishery resources. However, information on the genetic background of the small abalone is scarce. In this study, 20 polymorphic microsatellite DNA markers were identified using next-generation sequencing techniques and used to compare allelic variation between wild and released abalone populations in Korea. Using high-throughput genomic sequencing, a total of 1516 (2.26%; average length of 385 bp) reads containing simple sequence repeats were obtained from 86,011 raw reads. Among the 99 loci screened, 28 amplified successfully, and 20 were polymorphic. When comparing allelic variation between wild and released abalone populations, a total of 243 different alleles were observed, with 18.7 alleles per locus. High genetic diversity (mean heterozygosity = 0.81; mean allelic number = 15.5) was observed in both populations. A statistical analysis of the fixation index (F_ST) and analysis of molecular variance (AMOVA) indicated limited genetic differences between the two populations (F_ST = 0.002, p > 0.05). Although no significant reductions in the genetic diversity were found in the released population compared with the wild population (p > 0.05), the genetic diversity parameters revealed that the seeds released for stock abundance had a different genetic composition. These differences are likely a result of hatchery selection and inbreeding. Additionally, all the primer pair sets were effectively amplified in another congeneric species, H. diversicolor diversicolor, indicating that these primers are useful for both abalone species. These microsatellite loci may be valuable for future aquaculture and population genetic studies aimed at developing conservation and management plans for these two abalone species.     

Wild and hatchery populations of Korean starry flounder (Platichthys stellatus) compared using microsatellite DNA markers

Starry flounder (Platichthys stellatus) is an important sport and food fish found around the margins of the North Pacific. Aquaculture production of this species in Korea has increased because of its commercial value. Microsatellite DNA markers are a useful DNA-based tool for monitoring the genetic variation of starry flounder populations. In this study, 12 polymorphic microsatellite DNA markers were identified from a partial genomic starry flounder DNA library enriched in CA repeats, and used to compare allelic variation between wild and hatchery starry flounder populations in Korea. All loci were readily amplified and demonstrated high allelic diversity, with the number of alleles ranging from 6 to 18 in the wild population and from 2 to 12 in the farmed population. A total of 136 alleles were detected at the 12 microsatellite loci in the two populations. The mean observed and expected heterozygosities were 0.62 and 0.68, respectively, in the hatchery samples and 0.67 and 0.75, respectively, in the wild samples. These results indicate lower genetic variability in the hatchery population as compared to the wild population. Significant shifts in allelic frequencies were detected at eight loci, which resulted in a small but significant genetic differences between the wild and hatchery populations (F(ST) = 0.043, P < 0.05). Further studies with additional starry flounder sample collections are needed for comprehensive determinations of the genetic varieties between the wild and hatchery populations. These microsatellite loci may be valuable for future population genetic studies, monitoring the genetic variation for successful aquaculture management and the preservation of aquatic biodiversity.     

Isolation and Characterization of Microsatellite Markers for Passiflora contracta

Passiflora contracta Vitta (Passifloraceae) is an endemic species of the Atlantic Rainforest, one of the most species-rich ecoregions in the world, although extremely endangered. We have developed an enriched microsatellite library in order to fine-scale studies of the genetic structure of P. contracta. Twelve pairs of microsatellite primers were designed, and seven loci were successfully amplified and characterized by genotyping two wild populations of P. contracta. All seven loci were polymorphic, with an average number of alleles found being 4.8 and 5 per population. The cross-species transferability was tested using sister species Passiflora ovalis Vell. Ex Roemer. The development of these markers will contribute to the studies of population genetics in P. contracta as well as future studies concerning diversity patterns in the Atlantic Rainforest, and may also help to establish strategies for the conservation of this species.     

Elaeis oleifera Genomic-SSR Markers: Exploitation in Oil Palm Germplasm Diversity and Cross-Amplification in Arecaceae

Species-specific simple sequence repeat (SSR) markers are favored for genetic studies and marker-assisted selection (MAS) breeding for oil palm genetic improvement. This report characterizes 20 SSR markers from an Elaeis oleifera genomic library (gSSR). Characterization of the repeat type in 2000 sequences revealed a high percentage of di-nucleotides (63.6%), followed by tri-nucleotides (24.2%). Primer pairs were successfully designed for 394 of the E. oleifera gSSRs. Subsequent analysis showed the ability of the 20 selected E. oleifera gSSR markers to reveal genetic diversity in the genus Elaeis. The average Polymorphism Information Content (PIC) value for the SSRs was 0.402, with the tri-repeats showing the highest average PIC (0.626). Low values of observed heterozygosity (H(o)) (0.164) and highly positive fixation indices (F(is)) in the E. oleifera germplasm collection, compared to the E. guineensis, indicated an excess of homozygosity in E. oleifera. The transferability of the markers to closely related palms, Elaeis guineensis, Cocos nucifera and ornamental palms is also reported. Sequencing the amplicons of three selected E. oleifera gSSRs across both species and palm taxa revealed variations in the repeat-units. The study showed the potential of E. oleifera gSSR markers to reveal genetic diversity in the genus Elaeis. The markers are also a valuable genetic resource for studying E. oleifera and other genus in the Arecaceae family.     

Eleven Novel Polymorphic Microsatellite Loci for Oval Squid Sepioteuthis Lessoniana (Shiro-Ika Type)

The oval squid Sepioteuthis lessoniana is one of the most economically important squid species in Japan; however, its population structure is poorly understood due to the lack of hypervariable markers. Such information is critical for managing sustainable fisheries, as well as for ensuring the existence of wild S. lessoniana stocks. Eleven candidate microsatellite loci were isolated from a small insert genomic DNA library. Polymorphisms in these 11 loci were screened in 24 wild individuals. The number of alleles per locus was found to range from 5 to 19 alleles, and the observed heterozygosity ranged from 0.292 to 0.958. No evidence for linkage disequilibrium was detected among all the loci. The genotypic proportions conformed to Hardy-Weinberg equilibrium, except at one locus. In conclusion, these polymorphic microsatellite loci may be used to develop a genetic framework to manage S. lessoniana in the future.     

Isolation and Characterisation of 11 Polymorphic Microsatellite Markers in Papaver rhoeas L. (Corn Poppy), a Major Annual Plant Species from Cultivated Areas

Papaver rhoeas, an annual plant species in the Papaveraceae family, is part of the biodiversity of agricultural ecosystems and also a noxious agronomic weed. We developed microsatellite markers to study the genetic diversity of P. rhoeas, using an enriched microsatellite library coupled with 454 next-generation sequencing. A total of 13,825 sequences were obtained that yielded 1795 microsatellite loci. After discarding loci with less than six repeats of the microsatellite motif, automated primer design was successful for 598 loci. We tested 74 of these loci for amplification with a total of 97 primer pairs. Thirty loci passed our tests and were subsequently tested for polymorphism using 384 P. rhoeas plants originating from 12 populations from France. Of the 30 loci, 11 showed reliable polymorphism not affected by the presence of null alleles. The number of alleles and the expected heterozygosity ranged from 3 to 7.4 and from 0.27 to 0.73, respectively. A low but significant genetic differentiation among populations was observed (F_ST = 0.04; p < 0.001). The 11 validated polymorphic microsatellite markers developed in this work will be useful in studies of genetic diversity and population structure of P. rhoeas, assisting in designing management strategies for the control or the conservation of this species.     

Isolation and Characterization of 15 New Microsatellite Markers in Oncomelania hupensis, the Snail Intermediate Host of Schistosoma japonicum in Mainland China

Oncomelania hupensis is the unique intermediate host of Schistosoma japonicum, which plays a key role during the transmission of schistosomiasis. It is mainly found in the Yangtze River valley and mountains or hills in southwest China. In this paper, we described 15 new microsatellite makers in O. hupensis. Polymorphism of each locus was assessed in 80 individuals from four wild populations (n = 20 per population). The number of alleles per locus ranged from 6 to 29, with an average of 15.8. The observed (H(O)) and expected (H(E)) heterozygosities varied from 0.397 to 0.851 and from 0.696 to 0.948, respectively. These microsatellite markers will be useful for population genetic studies and genome mapping in O. hupensis.     

Development of 20 Microsatellite Markers for Solenocera crassicornis and Their Cross-Species Application in Solenocera melantho

Twenty microsatellite markers were isolated and characterized for Solenocera crassicornis from a (GT)13-enriched genomic library. Their polymorphisms were investigated using 44 wild individuals from the South Yellow Sea. Our investigation revealed that all the markers were polymorphic. The number of alleles per locus varied from 6 to 19 with an average of 12.35. The observed and expected heterozygosities ranged from 0.400 to 0.977 and from 0.609 to 0.940, with averages of 0.788 and 0.859, respectively. Four loci significantly deviated from Hardy-Weinberg equilibrium after Bonferroni's correction. Cross-species amplification was also conducted in Solenocera melantho collected from the East China Sea. The result showed that 14 loci could be amplified from Solenocera melantho DNAs. These polymorphic markers would be useful for assessment of genetic variation and population structure of S. crassicornis and S. melantho.     

Isolation and Characterization of 21 Microsatellite Loci in Cardiocrinum giganteum var. yunnanense (Liliaceae), an Important Economic Plant in China

Twenty-one microsatellite markers from the genome of Cardiocrinum giganteum var. yunnanense, an important economic plant in China, were developed with a fast isolation protocol by amplified fragment length polymorphism of sequences containing repeats (FIASCO). Polymorphism within each locus was assessed in 24 wild individuals from Gaoligong Mountains in western Yunnan Province, China. The number of alleles per locus ranged from 2 to 4 with a mean of 2.9. The expected and observed levels of heterozygosity ranged from 0.042 to 0.726 and from 0.000 to 1.000, with averages of 0.44 and 0.31, respectively. These polymorphic microsatellite markers should prove useful in population genetics studies and assessments of genetic variation to develop conservation and management strategies for this species.     

Development of Nine Markers and Characterization of the Microsatellite Loci in the Endangered Gymnogobius isaza (Gobiidae)

Gymnogobius isaza is a freshwater goby endemic to Lake Biwa, Japan. They experienced a drastic demographic bottleneck in the 1950s and 1980s and slightly recovered thereafter, but the population size is still very small. To reveal dynamics of genetic diversity of G. isaza, we developed nine microsatellite markers based on the sequence data of a related goby Chaenogobius annularis. Nine SSR (Simple Sequence Repeats) markers were successfully amplified for raw and formalin-fixed fish samples. The number of alleles and expected heterozygosities ranged from one to 10 and from 0.06 to 0.84, respectively, for the current samples, while one to 12 and 0.09 to 0.83 for historical samples. The markers described here will be useful for investigating the genetic diversity and gene flow and for conservation of G. isaza.     

Development of Seven Microsatellite Markers Using Next Generation Sequencing for the Conservation on the Korean Population of Dorcus hopei (E. Saunders, 1854) (Coleoptera,Lucanidae)

We developed microsatellite markers for genetic structural analyses of Dorcus hopei, a stag beetle species, using next generation sequencing and polymerase chain reaction (PCR)-based genotyping for regional populations. A total of 407,070,351 base pairs of genomic DNA containing >4000 microsatellite loci except AT repeats were sequenced. From 76 loci selected for primer design, 27 were polymorphic. Of these 27 markers, 10 were tested on three regional populations: two Chinese (Shichuan and Guangxi) and one Korean (Wanju). Three markers were excluded due to inconsistent amplification, genotyping errors, and Hardy-Weinberg equilibrium (HWE). By multi-locus genotyping, the allele number, observed heterozygosity and polymorphism information content of seven microsatellite loci were ranged 2‒10, 0.1333‒1.0000, and 0.1228‒0.8509, respectively. In an analysis on the genetic differentiation among regional populations including one Japanese population and one cross-breeding population, the individual colored bar-plots showed that both Chinese populations were closer to each other than to the Far East Asian populations. In Far East Asian populations, Wanju and Nirasaki populations could not be distinguished from each other because the frequency of genetic contents was very similar in some individuals of two populations. Moreover, the cross-breeding population contained all patterns of genetic contents shown in Chinese, Korean, and Japanese populations, compared with the genetic content frequency of each regional population. As a result, we examined whether the cross-breeding population might be a hybrid population, and might contain a possibility of interbreeding with Chinese populations in parental generations. Therefore, these markers will be useful for analyses of genetic diversity in populations, genetic relationships between regional populations, genetic structure analyses, and origin tests.     

Isolation and Characterization of Eleven Polymorphic Microsatellite Loci for the Valuable Medicinal Plant Dendrobium huoshanense and Cross-Species Amplification

Dendrobium huoshanense (Orchidaceae) is a perennial herb and a widely used medicinal plant in Traditional Chinese medicine (TCM) endemic to Huoshan County town in Anhui province in Southeast China. A microsatellite-enriched genomic DNA library of D. huoshanense was developed and screened to identify marker loci. Eleven polymorphic loci were isolated and analyzed by screening 25 individuals collected from a natural population. The number of alleles per locus ranged from 2 to 5. The observed and expected heterozygosities ranged from 0.227 to 0.818 and from 0.317 to 0.757, respectively. Two loci showed significant deviations from Hardy-Weinberg equilibrium and four of the pairwise comparisons of loci revealed linkage disequilibrium (p < 0.05). These microsatellite loci were cross-amplified for five congeneric species and seven loci can be amplified in all species. These simple sequence repeats (SSR) markers are useful in genetic studies of D. huoshanense and other related species and in conservation decision-making.     

Relationships among the A Genomes of Triticum L. Species as Evidenced by SSR Markers, in Iran

The relationships among 55 wheat accessions (47 accessions collected from Iran and eight accessions provided by the Institute of Plant Biology of the University of Zurich, Switzerland) belonging to eight species carrying A genome (Triticum monococcum L., T. boeoticum Boiss., T. urartu Tumanian ex Gandilyan, T. durum Desf., T. turgidum L., T. dicoccum Schrank ex Schübler, T. dicoccoides (Körn. ex Asch. & Graebner) Schweinf. and T. aestivum L.) were evaluated using 31 A genome specific microsatellite markers. A high level of polymorphism was observed among the accessions studied (PIC = 0.77). The highest gene diversity was revealed among T. durum genotypes, while the lowest genetic variation was found in T. dicoccoides accessions. The analysis of molecular variance (AMOVA) showed a significant genetic variance (75.56%) among these accessions, representing a high intra-specific genetic diversity within Triticum taxa in Iran. However, such a variance was not observed among their ploidy levels. Based on the genetic similarity analysis, the accessions collected from Iran were divided into two main groups: diploids and polyploids. The genetic similarity among the diploid and polyploid species was 0.85 and 0.89 respectively. There were no significant differences in A genome diversity from different geographic regions. Based on the genetic diversity analyses, we consider there is value in a greater sampling of each species in Iran to discover useful genes for breeding purposes.