Development of microsatellite markers in potato and their transferability in some members of Solanaceae

We have developed thirty new microsatellite markers in potato by screening genomic libraries and ESTs. Genomic libraries of potato cultivar Kufri Bahar were screened for sequences containing microsatellite motifs GA, GT, ACA, ATC, GAA, TAA and GATA. Using flanking sequences, PCR primers were designed for microsatellites identified from genomic libraries and ESTs. Sixteen new primer pairs from genomic libraries and fourteen from ESTs along with seven previously published primer pairs amplified PCR products in the selected genotypes comprising of 65 Solanum tuberosum lines and 14 other species of the potato gene pool. Neighbor-joining tree based on genetic distance matrix developed using microsatellite markers successfully distinguished all these genotypes in the expected size range. Seventeen microsatellites could also be cross-amplified in at least one of the five members of solanaceae, namely tomato, eggplant, pepper, petunia and tobacco. The new microsatellite markers obtained in this study will be useful in various genetic and taxonomic studies in potato and related genomes.     

CAPS-microsatellites: use of CAPS method to convert non-polymorphic microsatellites into useful markers

Microsatellites found in expressed sequence tags (ESTs) have several advantages in comparison to conventional microsatellites developed from genomic DNA. Advantages of EST-microsatellites include better transferability between the species and lower development cost of primer pairs. However, in many cases the amplified products of genomic DNA are larger than their expected sizes based on ESTs and these markers have low level of polymorphism. In the present study we report on a new approach as a modest modification of the cleavage amplified polymorphic sequence (CAPS) called CAPS-microsatellites. Using a total of 20 EST-microsatellite primer pairs on four Capsicum species and two Gossypium species we observed that all 20 monomorphic EST-microsatellites could be converted into polymorphic markers among the species used. Further analyses using a total of 37 F₂ individuals obtained from two Capsicum annuum L. lines indicated that CAPS-microsatellite markers usually segregated as co-dominant fashions, discriminating the homozygous from heterozygous genotypes and could be used in genetic analyses of plant species.     

Isolation and characterization of microsatellite loci in Penstemon rostriflorus (Plantaginaceae) and cross‐species amplification

Eight novel microsatellite primer pairs are presented for Penstemon rostriflorus, representing the first microsatellite markers available for this genus. Loci were characterized for 20 individuals from two populations in the Great Basin, USA. All loci are polymorphic within P. rostriflorus (seven to 13 alleles per locus; observed heterozygosity between 0.40 and 0.95), and therefore useful for population genetic studies within the species. Cross‐species transferability was tested on 40 additional species of Penstemon, and results indicate that these primers pairs will likely be useful for population genetic studies on many Penstemon species.     

Microsatellite markers developed from Theobroma cacao L. expressed sequence tags

Theobroma cacao L. expressed sequence tags (ESTs) were converted into useful genetic markers for fingerprinting individuals and genetic linkage mapping. Primers were designed to microsatellite‐containing ESTs. Twenty‐two T. cacao accessions, parents of various mapping populations segregating for disease resistance and crop yield characteristics, were tested. Twenty‐seven informative loci were discovered with 26 primer pairs. The number of detected alleles ranged from two to 11 and averaged 4.4 per locus. All 27 markers could be mapped into at least one of the existing F₁ or F₂ populations segregating for agronomically important traits.     

Isolation and characterization of microsatellite loci in Lesquerella fendleri (Brassicaceae) and cross‐species amplification

Fifteen novel microsatellite primer pairs are presented for Lesquerella fendleri, which were developed from seven dinucleotide, five trinucleotide and three tetranucleotide microsatellite DNA loci. These loci were characterized for 40 individuals from 24 localities throughout the species range. The number of alleles observed per locus ranged from three to 16, the observed heterozygosity ranged from 0.175 to 0.750, and the polymorphic information content ranged from 0.218 to 0.889. Cross‐species transferability tested on nine species of Lesquerella and one species of the related genus Physaria indicates that these primer pairs may be useful for population genetic studies of other species in Lesquerella and possibly other closely related genera.     

Development of thirty new polymorphic microsatellite primers for <Emphasis Type="Italic">Paeonia suffruticosa</Emphasis>

Four new microsatellite primer pairs were developed in tree peony (Paeonia suffruticosa) based on the database mining and other twenty-six primer pairs by fast isolation by AFLP of sequences containing repeats (FIASCO) method. The polymorphism of each locus was further evaluated in 40 individuals of one population plus 5 tree peony related species. The number of alleles per locus ranged from 3 to 7 and the expected (H_e) and observed (H_o) heterozygosity at each locus ranged from 0.42 to 0.78 and 0.28 to 0.59, respectively. These microsatellite markers will be useful for investigating genetic diversity and studies of population genetic structure of tree peony.     

Isolation and characterization of Ligustrum micranthum (Oleaceae) microsatellite loci using paired‐end Illumina reads

Twenty‐six microsatellite loci were developed and characterized for Ligustrum micranthum, a species endemic to the Ogasawara Islands, Japan. The genetic structure of this species must be clarified in order to restore the island's ecosystem. A total of 8511 primer pairs were designed from de novo sequencing. Of the 48 primer pairs selected, amplification and polymorphisms were tested using one population each from the Chichijima and Hahajima Islands of the Ogasawara Islands. Twenty‐six microsatellite loci were successfully amplified and the number of alleles for these loci ranged from five to 31 per locus, and the mean expected heterozygosities were 0.858 and 0.849, respectively. No significant deviation from the Hardy–Weinberg equilibrium was observed in either population, and no significant linkage disequilibrium was detected between any locus pair. The microsatellite loci reported in this study can be used in future studies to evaluate the genetic structure and mating system of L. micranthum.     

Evaluating the potential of barley and wheat microsatellite markers for genetic analysis of<Emphasis Type="Italic"> Elymus trachycaulus</Emphasis> complex species

The potential of barley and wheat microsatellite markers for genetic analysis of Elymus trachycaulus complex species was evaluated. A set of 25 barley and 3 wheat microsatellite markers were tested for their ability to cross-amplify DNA from four accessions of E. trachycaulus and two accessions Pseudoroegneria spicata. Thirteen barley (52%) and two (68%) wheat primer pairs successfully amplified consistent products from both E. trachycaulus and P. spicata species. Four of the 15 successful primer pairs produced visible polymorphisms among the accessions tested. A higher successful rate of cross-species amplification of barley and wheat microsatellite markers in E. trachycaulus and P. spicata was found in this study. These primer pairs are now available for use as markers in genetic analysis of E. trachycaulus complex species. Our results suggest that publicly available wheat and barley microsatellite markers are a valuable resource for the genetic characterization of wild Triticeae species.     

Transferability and Level of Heterozygosity of Microsatellite Markers in <Emphasis Type="Italic">Citrus</Emphasis> Species

Microsatellite markers are a powerful tool for genetic studies, including germplasm conservation, cultivar identification, and integration of linkage maps. Several works have shown that primer pairs designed for one species can be used in related species to facilitate wider application because it reduces the costs for primer development. The objective of this study was to evaluate the transferability of microsatellite primers which was previously developed from the genomic library of Pêra sweet orange (Citrus sinensis L. Osbeck) and to determine the level of heterozygosity between citrus accessions and related genera. Twenty-four microsatellite loci were evaluated on 12 genotypes of Citrus, Poncirus, and an intergeneric hybrid. All analyzed markers were transferable across all genotypes. Seventeen loci were polymorphic, and the number of alleles per loci ranged from one to six. The lowest level of heterozygosity was observed for Poncirus trifoliata (L.) Raf. cultivars while the highest level was for Swingle citrumelo. In general, microsatellite markers showed wide genetic variation and demonstrated that they can be useful in citrus breeding programs.     

Expressed sequence tag-derived microsatellite markers of perennial ryegrass (Lolium perenne L.)

An expressed sequence tag (EST) library of the key grassland species perennial ryegrass (Lolium perenne L.) has been exploited as a resource for microsatellite marker development. Out of 955 simple sequence repeat (SSR) containing ESTs, 744 were used for primer design. Primer amplification was tested in eight genotypes of L. perenne and L. multiflorum representing (grand-) parents of four mapping populations and resulted in 464 successfully amplified EST-SSRs. Three hundred and six primer pairs successfully amplified products in the mapping population VrnA derived from two of the eight genotypes included in the original screening and revealed SSR polymorphisms for 143 ESTs. Here, we report on 464 EST-derived SSR primer sequences of perennial ryegrass established in laboratory assays, providing a dedicated tool for marker assisted breeding and comparative mapping within and among forage and turf grasses. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Isolation and characterization of microsatellite loci from the orchid Serapias vomeracea (Orchidaceae) and cross‐priming to other Serapias species

In this paper we describe the isolation and characterization of six polymorphic microsatellite loci from the orchid Serapias vomeracea. This species is widely distributed in the Mediterranean region. Microsatellite loci were isolated from an enriched library and primer pairs were designed for 18 loci. Primer pairs for six loci amplified well and were tested on samples from southern Italy. Levels of genetic variability detected at these six loci are high, with numbers of alleles per locus ranging from 3 to 6, and observed heterozygosity (H_O) ranging from 0.35 to 0.86. All primer pairs tested amplified DNA from four other Serapias species, indicating that the primers are useful for population genetic studies throughout the genus.     

中国重要农业害虫韭菜迟眼蕈蚊多态性EST-SSR标记的开发

【背景】韭菜迟眼蕈蚊是我国重要的农业害虫,然而它的遗传资源有限。本研究旨在开发韭菜迟眼蕈蚊EST-SSR标记,为研究不同地区的韭菜迟眼蕈蚊种群结构和遗传多样性奠定基础。【方法】从韭菜迟眼蕈蚊的表达序列标签(EST序列)中设计16对简单重复序列(SSR)引物,进一步筛选出9对具有多态性的SSR引物。【结果】从42095条unigene中确定了3383个SSR位点。利用查找到的SSR位点共设计出16对引物,进一步检测筛选发现9对引物具有多态性,引物的每个位点平均有3.33个等位基因。利用9对引物对30头韭菜迟眼蕈蚊进行检测,共获得30个等位基因,观测杂合度和期望杂合度的范围分别为0.0000~0.6875和0.0370~0.6877;其中,9个位点中有5个位点显著偏离Hardy-Weinberg平衡。【结论与意义】本研究成功从迟眼蕈蚊EST序列中筛选出9个具有多态性的微卫星位点,这为进一步分析该害虫种群的遗传结构和遗传多样性奠定了基础。     

Development of expressed sequence tag-derived microsatellite markers for <Emphasis Type="Italic">Saccharina</Emphasis> (<Emphasis Type="Italic">Laminaria</Emphasis>) <Emphasis Type="Italic">japonica</Emphasis>

Expressed sequence tag-derived microsatellite markers (EST-SSR) were generated and characterized in Laminaria japonica using data mining from updated public EST databases and polymorphism testing. Fifty-eight of 578 ESTs (10.0%) containing various repeat motifs were used to design polymerase chain reaction (PCR) amplification primers. A total of 12 pairs of primer were generated and used in the PCR amplification. Alleles per locus ranged from two to ten (average of 5.7). The observed heterozygosities and expected heterozygosities were from 0.045 to 0.543 and from 0.056 to 0.814, respectively. All loci were in Hardy–Weinberg equilibrium and no linkage disequilibrium was detected. These robust, informative, and potentially transferable polymorphic markers appear suitable for population, genetic, parentage, and mapping studies of L. japonica.     

Abundance, variability and chromosomal location of microsatellites in wheat

The potential of microsatellite sequences as genetic markers in hexaploid wheat (Triticum aestivum) was investigated with respect to their abundance, variability, chromosomal location and usefulness in related species. By screening a lambda phage library, the total number of (GA)_n blocks was estimated to be 3.6 x 10⁴ and the number of (GT)_n blocks to be 2.3 x 10⁴ per haploid wheat genome. This results in an average distance of approximately 270 kb between these two microsatellite types combined. Based on sequence analysis data from 70 isolated microsatellites, it was found that wheat microsatellites are relatively long containing up to 40 dinucleotide repeats. Of the tested primer pairs, 36% resulted in fragments with a size corresponding to the expected length of the sequenced microsatellite clone. The variability of 15 microsatellite markers was investigated on 18 wheat accessions. Significantly, more variation was detected with the microsatellite markers than with RFLP markers with, on average, 4.6 different alleles per microsatellite. The 15 PCR-amplified microsatellites were further localized on chromosome arms using cytogenetic stocks of Chinese Spring. Finally, the primers for the 15 wheat microsatellites were used for PCR amplification with rye (Secale cereale) and barley accessions (Hordeum vulgare, H. spontaneum). Amplified fragments were observed for ten primer pairs with barley DNA and for nine primer pairs with rye DNA as template. A microsatellite was found by dot blot analysis in the PCR products of barley and rye DNA for only one primer pair.     

Assessment of genetic diversity and relationships of Krachaai Sayam,an endemic plant in Thailand using microsatellite markers

Nineteen microsatellite markers were developed from Boesenbergia siamensis (Gagnep.) P. Sirirugsa, an endemic plant of Kanchanaburi Province, Thailand and used to determine genetic diversity of this plant. The number of alleles of each locus varied from 4 to 16 in 25 individual samples. The average values of observed and expected heterozygosities were 0.577 and 0.804, respectively. The polymorphic information content value ranged between 0.486 and 0.912. Ten loci significantly deviated from Hardy–Weinberg equilibrium, and eight pairs of loci showed significant evidence of linkage disequilibrium. Moreover, these newly developed microsatellite markers were used to determine cross-species amplification with three samples each of B. thorelii (Gagnep.) Loes., B. rotunda (L.) Mansf. and Kaempferia parviflora Wall. Of the 19 markers developed, 13 (68.42%) primer pairs were able to be used with B. thorelii (Gagnep.) Loes. and K. parviflora Wall., while 12 (63.16%) primer pairs were able to be used with B. rotunda (L.) Mansf. These microsatellite markers will be useful for further genetic analysis of this endemic plant as well as related species.     

Development and characterisation of microsatellite markers for the medicinal plant Scutellaria baicalensis (Lamiaceae)

Scutellaria baicalensis is a popular medicinal plant that is on the verge of extinction due to uncontrolled harvesting, habitat destruction and deterioration of its ecosystem. We isolated and characterised 21 microsatellite loci in this species. Ninety-four individuals from six populations were used to test the polymorphism of the microsatellite loci. The number of alleles per locus ranged from 1 to 13, with a mean of 7.2. Observed and expected heterozygosities varied from 0.000 to 1.000 and 0.000 to 0.938, respectively. Among these new microsatellite markers, only two loci showed significant deviation from Hardy–Weinberg equilibrium. No locus pairs showed significant linkage disequilibrium. The 21 primer pairs were tested in other Scutellaria species. Most of these primer pairs worked successfully, except for Scut18. These new microsatellite markers could be applied to investigate the genetic diversity and population genetic structure of S. baicalensis and its closely related species.     

Isolation and characterization of microsatellite loci from Larix kaempferi

Microsatellites were isolated and characterized for Japanese larch, Larix kaempferi, a conifer species distributed in Japan. A larch genomic DNA library enriched for (AG)_n repeats was screened using the colony polymerase chain reaction method and 145 unique microsatellite containing sequences were obtained. Seventy‐two primer pairs were designed and 30 produced single‐locus products, and 19 of them were polymorphic. The expected heterozygosity ranged from 0.566 to 0.951. These 19 polymorphic microsatellite loci should be valuable markers for genetic studies on Japanese larch.     

Identification of microsatellite markers in the red flour beetle,Tribolium castaneum

We isolated and characterized microsatellite markers for the red flour beetle Tribolium castaneum, an important model species for studies in various areas of evolutionary biology and ecology. A microsatellite‐enriched genomic library was constructed and screened with single stranded oligonucleotide probes [(CCT)₁₇, (AAT)₁₇ and (CAG)₁₇]. Forty‐five primer pairs were designed of which 19 pairs produced successful amplification. Polymorphism screening involved beetles from five beetle strains and revealed 15 polymorphic and four monomorphic markers. The development of polymorphic microsatellite markers will facilitate future ecological and genetic studies involving T. castaneum beetles.     

Microsatellite markers for genome analysis in Brassica. II. Assignment of rapeseed microsatellites to the A and C genomes and genetic mapping in Brassica oleracea L.

Microsatellites are highly polymorphic and efficient markers for the analysis of plant genomes. Primer specificity, however, may restrict the applicability of these markers even between closely related species for comparative mapping studies. We have demonstrated that the majority of microsatellites identified in oilseed rape (Brassica napus L; AC genome) correspond to loci which can be easily assigned to the A and C progenitor genomes. A study with 63 primer pairs has shown that 54% detect two loci, one from each genome, while 25% and 21%, respectively, are either A or C genome-specific. The distribution of rapeseed microsatellites in the C genome was investigated by genetic mapping in Brassica oleracea L. Ninety two dinucleotide microsatellites were screened for polymorphism in an F₂ population derived from a cross between collard and cauliflower, for which an RFLP map has been constructed previously. Thirty three primer pairs (35.7%) have yielded either unspecific or no PCR products whereas the remaining primer pairs amplified one or more distinct loci. The level of polymorphism found in the mapping population was 49.2%. A total of 29 primer pairs disclosed 34 loci of which 31 are evenly distributed on 8 of the 9 B. oleracea linkage groups. For the remaining three markers linkage could not be established. Our results showed that microsatellite markers from the composite genome of B. napus can serve as a useful marker system in genetic studies and for plant-breeding objectives in B. oleracea. Received: 14 April 2000 / Accepted: 3 July 2000