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Genetic profiling of the biodiversity in cultivated crop plants is necessary to preserve important genes and utilize them in a breeding program. Cucumber is used as a model plant to study various characteristics of Cucurbitaceae. Its adaptation to a wide range of climatic conditions suggested analyzing the landraces. The present study was conducted to evaluate the differences, at the genetic level, among landraces spanning five continents. DNA extracted from fifty-six landraces selected from USDA germplasm bank to cover a global representative sample of world cucumber landraces was used for polymerase chain reaction using twenty-eight polymorphic expressed sequence tags simple sequence repeat (EST-SSR) markers. Twenty-eight EST-SSR markers covering all seven chromosomes yielded 98 bands with an average of 3.42 bands per marker. Polymorphic information content ranged from 0.00 (EC35) to 0.74 (EC17) with an average of 0.34. Six clusters provided an appropriate summary of the variation among the landraces, with the two largest groups including 32 (Asiatic) and 17 (European and American) landraces, respectively. Four small groups, three with two members, and one with one member (PI 525155-Egypt) were dissimilar to the two main groups. Landraces from the same region were often clustered together. Genetic similarity of the landraces was revealed by marker banding patterns. The locations of genetic diversity for cucumber landraces can be identified from this study., (© 2024. The Author(s).)

Orchidantha chinensis T. L. Wu, an endemic species in China, is listed as a key protected wild plant in Guangdong Province. However, the lack of reports on the chloroplast genome and simple sequence repeat (SSR) markers has hindered the assessment of its genetic diversity and conservation strategies. The limited number of molecular markers to assess the genetic diversity of this species, and thus develop proper conservation strategies, highlighted the urgent need to develop new ones. This study developed new SSR markers and investigated genetic variation using 96 samples of O. chinensis from seven populations. Through high-throughput sequencing, a complete chloroplast genome of 134,407 bp was assembled. A maximum-likelihood phylogenetic tree, based on the chloroplast genome, showed that O. chinensis is closely related to Ravenala madagascariensis . The study identified 52 chloroplast SSRs (cpSSRs) and 5094 expressed sequence tag SSRs (EST-SSRs) loci from the chloroplast genome and leaf transcriptome, respectively. Twenty-one polymorphic SSRs (seven cpSSRs and fourteen EST-SSRs) were selected to evaluate the genetic variation in 96 accessions across seven populations. Among these markers, one cpSSR and 11 EST-SSRs had high polymorphism information content (>0.5). Cluster, principal coordinate, and genetic structure analyses indicated that groups G1 and G6 were distinct from the other five groups. However, an analysis of molecular variance showed greater variation within groups than among groups. The genetic distance among the populations was significantly positively correlated with geographical distance. These findings provide new markers for studying the genetic variability of O. chinensis and offer a theoretical foundation for its conservation strategies.

In the present study, novel genomic-SSR (g-SSR) markers generated in our laboratory were used to characterize Tinospora cordifolia and related species. The g-SSR marker was also compared with EST-SSR and SCoT markers used earlier in our laboratory to assess the genetic diversity of T. cordifolia . A total of 26 accessions of T. cordifolia and 1 accession each of Tinospora rumphii and Tinospora sinensis were characterized using 65 novel g-SSR markers. A total of 125 alleles were detected with 49 polymorphic g-SSR markers. The number of alleles per locus varied from 1-4 with a mean value of 2.55 alleles per locus. Mean PIC, gene diversity, and heterozygosity were estimated to be 0.33, 0.41, and 0.65, respectively. The two species, namely T. rumphii and T. sinensis , showed cross-species transferability of g-SSRs developed in T. cordifolia . The success rate of cross-species transferability in T. rumphii was 95.3% and 93.8% in T. sinensis , proving the usefulness of this marker in genetic diversity studies of related species. The Tinospora accessions were also used for molecular characterization using SCoT and EST-SSR markers and compared for genetic diversity and cross-species transferability. The PIC, gene diversity, heterozygosity, and principal coordinate analysis showed that g-SSR is the better maker for a genetic diversity study of T. cordifolia. Additionally, high cross-species transferability of g-SSRs was found (95.3% and 93.8%) compared to EST-SSRs (68.8% and 67.7%) in T. rumphii and T. sinensis , respectively.

Background: Monochasma savatieri Franch. ex Maxim is a medicinally valuable herb. However, the collection and protection of the wild germplasm resources of M. savatieri are still insufficient, and their genetic diversity and population structure have been poorly studied., Results: We collected and examined 46 M. savatieri individuals from Fujian, Hunan, Jiangxi, and Zhejiang provinces for genetic diversity and population structure, using 33 newly developed expressed sequence tag-simple sequence repeat (EST-SSR) markers. Applying these markers, we detected a total of 208 alleles, with an average of 6.303 alleles per locus. The polymorphic information content varied from 0.138 to 0.884 (average: 0.668), indicating a high level of polymorphism. At the population level, there was a low degree of genetic diversity among populations (I = 0.535, He = 0.342), with Zhejiang individuals showing the highest genetic diversity among the four populations (Fst = 0.497), which indicated little gene flow within the M. savatieri populations (Nm = 0.253). Mantel test analysis revealed a significant positive correlation between geographical and genetic distance among populations (R 2  = 0.3304, p < 0.05), and structure and principal coordinate analyses supported classification of populations into three clusters, which was consistent with the findings of cluster analysis., Conclusions: As a rare medicinal plants, the protection of M. savatieri does not look optimistic, and accordingly, protective efforts should be beefed up on the natural wild populations. This study provided novel tools and insights for designing effective collection and conservation strategies for M. savatieri., (© 2022. The Author(s).)

High-throughput sequencing of the Phoebe bournei transcriptome was performed, and novel SSR markers were identified. A total of 73,518 nonredundant unigenes were assembled and annotated by sequence similarity searching in diverse public databases. A total of 40,853 SSRs were identified from 73,518 unigenes. Twenty-three pairs of polymorphic EST-SSR markers were selected from 98 markers and used for genetic analyses in 75 individuals from three P. bournei populations. The 23 pairs of markers could detect abundant genetic information from the samples (PIC = 0.769), and cross-species amplification was successfully performed in other related species. Three populations had high level of genetic diversity (He = 0.658 in average), of which the population YS from Jiangxi province had the most abundant genetic diversity (He = 0.722). The results of genetic structure analyses showed that the population YS from Jiangxi province had obvious genetic differences from the other two populations, and the genetic information of the population SX from Fujian province was related to that of the population LC from Guangdong province and the population YS. The transcriptomic resources and EST-SSR markers are valuable tools not only for the ecological conservation of P. bournei but also for phylogenetic studies.

Olive is considered one of the oldest and the most important cultivated fruit trees in Albania. In the present study, the genetic diversity and structure of Albanian olive germplasm is represented by a set of 194 olive genotypes collected in-situ in their natural ecosystems and in the ex-situ collection. The study was conducted using 26 microsatellite markers (14 genomic SSR and 12 Expressed Sequence Tag microsatellites). The identity analysis revealed 183 unique genotypes. Genetic distance-based and model-based Bayesian analyses were used to investigate the genetic diversity, relatedness, and the partitioning of the genetic variability among the Albanian olive germplasm. The genetic distance-based analysis grouped olives into 12 clusters, with an average similarity of 50.9%. Albanian native olives clustered in one main group separated from introduced foreign cultivars, which was also supported by Principal Coordinate Analysis (PCoA) and model-based methods. A core collection of 57 genotypes representing all allelic richness found in Albanian germplasm was developed for the first time. Herein, we report the first extended genetic characterization and structure of olive germplasm in Albania. The findings suggest that Albanian olive germplasm is a unique gene pool and provides an interesting genetic basis for breeding programs.

Background: The Lycoris genus includes many ornamentally and medicinally important species. Polyploidization and hybridization are considered modes of speciation in this genus, implying great genetic diversity. However, the lack of effective molecular markers has limited the genetic analysis of this genus., Results: In this study, mining of EST-SSR markers was performed using transcriptome sequences of L. aurea, and 839 primer pairs for non-redundant EST-SSRs were successfully designed. A subset of 60 pairs was randomly selected for validation, of which 44 pairs could amplify products of the expected size. Cross-species transferability of the 60 primer pairs among Lycoris species were assessed in L. radiata Hreb, L. sprengeri Comes ex Baker, L. chinensis Traub and L. anhuiensis, of which between 38 to 77% of the primers were able to amplify products in these Lycoris species. Furthermore, 20 and 10 amplification products were selected for sequencing verification in L. aurea and L. radiata respectively. All products were validated as expected SSRs. In addition, 15 SSRs, including 10 sequence-verified and 5 unverified SSRs were selected and used to evaluate the genetic diversity of seven L. radiata lines. Among these, there were three sterile lines, three fertile lines and one line represented by the offspring of one fertile line. Unweighted pair group method with arithmetic mean analysis (UPGMA) demonstrated that the outgroup, L. aurea was separated from L. radiata lines and that the seven L. radiata lines were clustered into two groups, consistent with their fertility. Interestingly, even a dendrogram with 34 individuals representing the seven L. radiata lines was almost consistent with fertility., Conclusions: This study supplies a pool of potential 839 non-redundant SSR markers for genetic analysis of Lycoris genus, that present high amplification rate, transferability and efficiency, which will facilitate genetic analysis and breeding program in Lycoris.

Background: Lilac (Syringa oblata) is an important woody plant with high ornamental value. However, very limited genetic marker resources are currently available, and little is known about the genetic architecture of important ornamental traits for S. oblata, which is hindering its genetic studies. Therefore, it is of great significance to develop effective molecular markers and understand the genetic architecture of complex floral traits for the genetic research of S. oblata., Results: In this study, a total of 10,988 SSRs were obtained from 9864 unigene sequences with an average of one SSR per 8.13 kb, of which di-nucleotide repeats were the dominant type (32.86%, 3611). A set of 2042 primer pairs were validated, out of which 932 (45.7%) exhibited successful amplifications, and 248 (12.1%) were polymorphic in eight S. oblata individuals. In addition, 30 polymorphic EST-SSR markers were further used to assess the genetic diversity and the population structure of 192 cultivated S. oblata individuals. Two hundred thirty-four alleles were detected, and the PIC values ranged from 0.23 to 0.88 with an average of 0.51, indicating a high level of genetic diversity within this cultivated population. The analysis of population structure showed two major subgroups in the association population. Finally, 20 significant associations were identified involving 17 markers with nine floral traits using the mixed linear model. Moreover, marker SO104, SO695 and SO790 had significant relationship with more than one trait., Conclusion: The results showed newly developed markers were valuable resource and provided powerful tools for genetic breeding of lilac. Beyond that, our study could serve an efficient foundation for further facilitate genetic improvement of floral traits for lilac.

The genus Rhododendron, known for large impressive flowers is widely distributed throughout the world. Rhododendrons have limited genetic information, despite of comprising high species diversity, morphological overlap and weak genetic barrier. In present study, expressed sequence tag (EST) data from Rhododendron catawbiense Michx (Subgenus Hymenanthes, Section Ponticum) and Rhododendron mucronatum var. ripense (Makino) E.H. Wilson (Subgenus Tsutsusi, Section Tsutsusi) were utilized for mining and identification of the SSRs for genetic diversity analysis of R. arboreum Smith (Subgenus Tsutsusi, Section Tsutsusi). A total of 249 SSRs were developed from 1767 contigs. Di-nucleotide was found to be most abundant repeat followed by tri- and tetra-nucleotide repeats. The motif AG/CT was most common di-nucleotide motif (31.73%), whereas, AAC/GTT (8.43%), ACG/CGT (8.03%), AAG/CTT (7.23%) and AGG/CCT (6.43%) were most abundant tri-nucleotide repeat motif. Among these SSRs, 168 sequences were only fit into the criteria to design flanking primer pairs. A total of 30 randomly selected primer pairs were utilized for validation and genetic diversity study in 36 genotypes of R. arboreum collected from western Himalayan region. In aggregate, 26 SSR markers (86.66%) produced good and repeatable amplifications. Expected heterozygosity (H E ) ranged from 0.322 to 0.841 and observed heterozygosity (H O ) ranged from 0.327 to 1.000 and PIC value ranged from 0.008 to 0.786. These primers were able to distinguish the geographic differences of occurrence based on cluster analysis. These developed EST-SSRs can be useful in future population genetics analysis and micro-evolutionary studies in Rhododendron species.

Erect milkvetch (Astragalus adsurgens Pall.) is a major legume forage plant widely grown in Northern China. However, the lack of molecular markers has limited its research into its genetic diversity and work on germplasm improvement. In this study, a total of 39,163 EST-SSR loci were identified from 30,262 unigene sequences in the erect milkvetch transcriptome using Illumina sequencing. Moreover, 22,367 EST-SSR primer pairs (PPs) were successfully designed. In addition, 100 PPs were synthesized and preliminarily screened in two accessions; of these, 90 were determined to be clear and stable EST-SSR markers. Fifty-one PPs were randomly selected in order to assess the genetic diversity of 27 erect milkvetch accessions. The average polymorphism information content of the 51 PPs was 0.682. Greater genetic diversity was detected in accessions from Inner Mongolia and in the group of landrace and wild erect milkvetch accessions. This study provides an important resource for germplasm improvement and genetic diversity analysis in erect milkvetch.

Ligusticum chuanxiong is a well-known traditional Chinese medicine plant. The study on its molecular markers development and germplasm resources is very important. In this study, we obtained 24 422 unigenes by assembling transcriptome sequencing reads of L. chuanxiong root. EST-SSR was detected and 4 073 SSR loci were identified. EST-SSR distribution and characteristic analysis results showed that the mono-nucleotide repeats were the main repeat types, accounting for 41.0%. In addition, the sequences containing SSR were functionally annotated in Gene Ontology (GO) and KEGG pathway and were assigned to 49 GO categories, 242 KEGG pathways, among them 2 201 sequences were annotated against Nr database. By validating 235 EST-SSRs,74 primer pairs were ultimately proved to have high quality amplification. Subsequently, genetic diversity analysis, UPGMA cluster analysis, PCoA analysis and population structure analysis of 34 L. chuanxiong germplasm resources were carried out with 74 primer pairs. In both UPGMA tree and PCoA results, L. chuanxiong resources were clustered into two groups, which are believed to be partial related to their geographical distribution. In this study, EST-SSRs in L. chuanxiong was firstly identified, and newly developed molecular markers would contribute significantly to further genetic diversity study, the purity detection, gene mapping, and molecular breeding., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Chinese Pharmaceutical Association.)

The paucity of molecular markers limits the application of genetic and genomic research in date palm (Phoenix dactylifera L.). Availability of expressed sequence tag (EST) sequences in date palm may provide a good resource for developing gene-based markers. This study characterizes a substantial fraction of transcriptome sequences containing simple sequence repeats (SSRs) from the EST sequences in date palm. The EST sequences studied are mainly homologous to those of Elaeis guineensis and Musa acuminata. A total of 911 gene-based SSR markers, characterized with functional annotations, have provided a useful basis not only for discovering candidate genes and understanding genetic basis of traits of interest but also for developing genetic and genomic tools for molecular research in date palm, such as diversity study, quantitative trait locus (QTL) mapping, and molecular breeding. The procedures of DNA extraction, polymerase chain reaction (PCR) amplification of these gene-based SSR markers, and gel electrophoresis of PCR products are described in this chapter.

Tinospora cordifolia is known for its medicinal properties owing to the presence of useful constituents such as terpenes, glycosides, steroids, alkaloids, and flavonoids belonging to secondary metabolism origin. However, there is little information available pertaining to critical genomic elements (ESTs, molecular markers) necessary for judicious exploitation of its germplasm. We employed 454 GS-FLX pyrosequencing of entire transcripts and altogether ∼25 K assembled transcripts or Expressed sequence tags (ESTs) were identified. As the interest in T. cordifolia is primarily due to its secondary metabolite constituents, the ESTs pertaining to terpenoids biosynthetic pathway were identified in the present study. Additionally, several ESTs were assigned to different transcription factor families. To validate our transcripts dataset, the novel EST-SSR markers were generated to assess the genetic diversity among germplasm of T. cordifolia. These EST-SSR markers were found to be polymorphic and the dendrogram based on dice similarity index revealed three distinct clustering of accessions. The present study demonstrates effectiveness in using both NEWBLER and MIRA sequence read assembler software for enriching transcript-dataset and thus enables better exploitation of EST resources for mining candidate genes and designing molecular markers.

Background: Simple sequence repeats (SSRs) are defined as sequence repeat units between 1 and 6 bp that occur in both coding and non-coding regions abundant in eukaryotic genomes, which may affect the expression of genes. In this study, expressed sequence tags (ESTs) of eight Prunus species were analyzed for in silico mining of EST-SSRs, protein annotation, and open reading frames (ORFs), and the identification of codon repetitions., Results: A total of 316 SSRs were identified using MISA software. Dinucleotide SSR motifs (26.31 %) were found to be the most abundant type of repeats, followed by tri- (14.58 %), tetra- (0.53 %), and penta- (0.27 %) nucleotide motifs. An attempt was made to design primer pairs for 316 identified SSRs but these were successful for only 175 SSR sequences. The positions of SSRs with respect to ORFs were detected, and annotation of sequences containing SSRs was performed to assign function to each sequence. SSRs were also characterized (in terms of position in the reference genome and associated gene) using the two available Prunus reference genomes (mei and peach). Finally, 38 SSR markers were validated across peach, almond, plum, and apricot genotypes. This validation showed a higher transferability level of EST-SSR developed in P. mume (mei) in comparison with the rest of species analyzed., Conclusions: Findings will aid analysis of functionally important molecular markers and facilitate the analysis of genetic diversity.

Background: The allohexaploid Crambe abyssinica (crambe) is an oilseed crop that has been recognized for its potential value in the chemical industry, particularly in terms of producing high-erucic acid content vegetable oil. However, as an understudied crop, improvement of crambe has been hampered by the lack of genetic and genomic information to enhance its yield, oil quality and resistance against biotic and abiotic stress. Development of molecular markers is therefore of great significance to facilitate genetic improvement of crambe., Results: In this study, high-throughput sequencing was performed to generate sequences for the transcriptome and genome of a widely planted crambe cultivar, Galactica. A total of 186,778 expressed sequence tag (EST) contigs as 8,130,350 genomic contigs were assembled as well. Altogether, 82,523 pairs of primers were designed in the flanking sequences of the simple sequence repeat (SSR) within these contigs. Virtual PCR analysis showed that a fraction of these primers could be mapped onto the genomes of related species of Brassica, including Brassica rapa, B. oleraceae and B. napus. Genetic diversity analysis using a subset of 166 markers on 30 independent C. abyssinica accessions exhibited that 1) 95 % of the designed SSRs were polymorphic among these accessions; 2) the polymorphism information content (PIC) value of the markers ranged from 0.13 to 0.89; 3) the genetic distances (coefficient NEI72) between accessions varied from 0.06 to 0.36. Cluster analysis subsequent on the accessions demonstrated consistency with crambe breeding history. F-statistics analysis revealed a moderate level of genetic differentiation in C. abyssinica (Gst = 0.3934) and a accordingly low estimated gene flow (Nm = 0.7709)., Conclusion: Application of high-throughput sequencing technology has facilitated SSR marker development, which was successfully employed in evaluating genetic diversity of C. abyssinica as demonstrated in our study. Results showed these molecular markers were robust and provided powerful tools for assessing genetic diversity and estimating crambe breeding history. Moreover, the SSR primers and sequence information developed in the study are freely available to the research community.

Gynostemma pentaphyllum is an important medicinal herb of the Cucurbitaceae family, but limited genomic data have hindered genetic studies. In this study, transcriptomes of two closely-related Gynostemma species, Gynostemma cardiospermum and G. pentaphyllum, were sequenced using Illumina paired-end sequencing technology. A total of 71,607 nonredundant unigenes were assembled. Of these unigenes, 60.45% (43,288) were annotated based on sequence similarity search with known proteins. A total of 11,059 unigenes were identified in the Kyoto Encyclopedia of Genes and Genomes Pathway (KEGG) database. A total of 3891 simple sequence repeats (SSRs) were detected in 3526 nonredundant unigenes, 2596 primer pairs were designed and 360 of them were randomly selected for validation. Of these, 268 primer pairs yielded clear products among six G. pentaphyllum samples. Thirty polymorphic SSR markers were used to test polymorphism and transferability in Gynostemma. Finally, 15 SSR makers that amplified in all 12 Gynostemma species were used to assess genetic diversity. Our results generated a comprehensive sequence resource for Gynostemma research.

The recent exponential increase in the number of next generation sequencing studies provides a new source of data for the discovery of functional genomics based markers. The RNA-seq and small RNA-seq provide a new source for the discovery of differentially expressed SSRs (simple sequence repeats) as biomarkers in various diseases. In the present study, for the first time, we applied RNA-seq SSR to find new biomarkers for pancreatic cancer (PC) diagnosis. Analysis of RNA-seq data revealed a significant alternation in the frequency of SSR motifs during cancer progression. In particular, RNA-seq SSR showed an increase in the frequencies of GCC/GGC and GCG/CGC motifs in PC samples compared to healthy pancreas. These findings were further confirmed using meta-analysis of EST-SSR data in 11 different cancers. Interestingly, the genes containing GCC/GGC and GCG/CGC motifs in their sequences were involved in many cancer-related biological processes, particularly regulation processes. The small RNA-seq data were also mined for the conserved patterns in SSR frequencies (sRNA-seq SSR) during cancer progression. Based on the results, we suggest the potential use of GCC/GGC and GCG/CGC motifs as biomarkers in PC. Based on the findings of this study, it seems that RNA-seq SSR and sRNA-seq SSR could open a new paradigm in the diagnostic and even therapeutic strategies for PC along the other types of cancers., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Scutellaria baicalensis Georgi is an herbaceous perennial plant used as one of the staple Chinese herbal medicines in China with a long officinal history. However, research on S. baicalensis is currently limited due to the lack of genome and gene expression information. A full-length cDNA library from leaves and roots of S. baicalensis subjected to water deficit and heat, conditions that have been shown to affect baicalein accumulation, was constructed. There were 6491 expressed sequence tags (ESTs) obtained. UniGenes were assembled by BLAST similarity searches and annotated with Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). A total of 78 simple sequence repeats (SSRs) were identified and SSR markers associated with the active ingredients of S. baicalensis were selected. EST-SSR transferability was determined from 5 populations from different areas. This study is the first to produce a large volume of gene expression data from S. baicalensis to facilitate gene discovery in S. baicalensis and provide an important resource for molecular genetic and functional genomic studies in this species., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The genus Arachis (Fabaceae), which originated in South America, consists of 80 species. Based on morphological traits and cross-compatibility among the species, the genus is divided into nine taxonomic sections. Arachis is the largest section including the economically valuable cultivated peanut (A. hypogaea). Seven genic sequences were utilized to better understand the phylogenetic relationships between species of genus Arachis. Our study displayed four clades of species of Arachis. Arachis triseminata was genetically isolated from all other species of Arachis studied, and it formed the basal clade with A. retusa and A. dardani from the most ancient sections Extranervosae and Heteranthae, respectively. Species of section Arachis formed a separated single clade from all other species, within which species having B and D genome clustered in one subgroup and three species characterized with an A genome grouped together in another subgroup. A divergent clade including species from five sections was sister to the clade of section Arachis. Between the sister clades and the basal clade there was a clade containing species from the more advanced sections. Phylogenetic relationships of all the species of Arachis using multiple genic sequences were similar to the phylogenies produced with single-copy genes.

We analyzed the mantle transcriptome of pearl oyster Pinctada maxima and developed EST-SSR markers using Illumina HiSeq 2000 paired-end sequencing technology. A total of 49,500,748 raw reads were generated. De novo assembly generated 108,704 unigenes with an average length of 407 bp. Sequence similarity search with known proteins or nucleotides revealed that 30,200 (27.78%) and 25,824 (23.76%) consensus sequences were homologous with the sequences in the non-redundant protein and Swiss-Prot databases, respectively, and that 19,701 (18.12%) of these unigenes were possibly involved in approximately 234 known signaling pathways in the Kyoto Encyclopedia of Genes and Genomes database. Ninety one biomineralization-related unigenes were detected. In a cultured stock, 1764 simple sequence repeats were identified and 56 primer pairs were randomly selected and tested. The rate of successful amplification was 68.3%. The developed molecular markers are helpful for further studies on genetic linkage analysis, gene localization, and quantitative trait loci mapping.

The clam Meretrix meretrix is an important commercial bivalve distributed in the coastal areas of South and Southeast Asia. In this study, marker-trait association analyses were performed based on the stock materials of M. meretrix with different vibrio-resistance profile obtained by selective breeding. Forty-eight EST-SSR markers were screened and 27 polymorphic SSRs of them were genotyped in the clam stocks with different resistance to Vibrio parahaemolyticus (11-R and 11-S) and to Vibrio harveyi (09-R and 09-C). Allele frequency distributions of the SSRs among different stocks were compared using Pearson's Chi-square test, and three functional EST-SSR markers (MM959, MM4765 and MM8364) were found to be associated with vibrio-resistance trait. The 140-bp allele of MM959 and 128-bp allele of MM4765 had significantly higher frequencies in resistant groups (11-R and 09-R) than in susceptive/control groups (11-S and 09-C) (P < 0.01), which suggested that the clams carrying these two alleles have stronger resistance against vibrio. Clam individuals of 11-S were divided into three subgroups based on the survival time post-challenge, and the multi-dimensional scaling (MDS) analysis showed that clusters generated by genetic similarity revealed by the three SSR markers were consistent with the three subgroups distinctions. The putative functions of contig959, contig4765 and contig8364 also suggested that the three SSR-involved genes might play important roles in immunity of M. meretrix. All these results supported that EST-SSR markers MM959, MM4765 and MM8364 were associated with vibrio-resistance and would be useful for marker-assisted selection (MAS) in M. meretrix genetic breeding., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Chimonanthus praecox, a member of the Calycanthaceae family, is a unique, traditional, and famous flowering economic tree species in China. Despite the existence of several varieties, only a few cultivars have been formally named. Currently, expression sequence tag–simple sequence repeat (EST-SSR) markers are extensively used to identify different species and varieties; a large number of microsatellites can be identified from transcriptome databases. A total of 162,638 unigenes were assembled using RNA-seq; 82,778 unigenes were annotated using the Nr, Nt, Swiss-Prot, Pfam, GO, KOG, and KEGG databases. In total, 13,556 SSR loci were detected from 11,691 unigenes, with trinucleotide repeat motifs being the most abundant among the six repeat motifs. To develop the markers, 64,440 pairs of SSR primers with polymorphism potential were designed, and 75 pairs of primers were randomly selected for amplification. Among these markers, seven pairs produced amplified fragments of the expected size with high polymorphism. Using these markers, 12 C. praecox varieties were clustered into two monophyletic clades. Microsatellites in the transcriptome of C. praecox exhibit rich types, strong specificity, and great polymorphism potential. These EST-SSR markers serve as molecular technical methods for identifying different varieties of C. praecox and facilitate the exploration of a large number of candidate genes associated with important traits. [ABSTRACT FROM AUTHOR]

Phaseolus coccineus L. is a highly valuable crop for human consumption with a high protein content and other associated health benefits. Herein, 14 P. coccineus L. landraces were selected for genetic characterization: two Protected Geographical Indication (PGI) landraces from the Prespon area, namely "Gigantes" ("G") and "Elephantes" ("E"), and 12 additional landraces from the Greek Gene Bank collection of beans (PC1–PC12). The genetic diversity among these landraces was assessed using capillary electrophoresis utilizing fluorescence-labeled Simple Sequence Repeat (SSR) and Expressed Sequence Tag (EST); Simple Sequence Repeat (SSR) is a molecular marker technology. The "G" and "E" Prespon landraces were clearly distinguished among them, as well as from the PC1 to PC12 landraces, indicating the unique genetic identity of the Prespon beans. Overall, the genetic characterization of the abundant Greek bean germplasm using molecular markers can aid in the genetic identification of "G" and "E" Prespon beans, thus preventing any form of fraudulent practices as well as supporting traceability management strategies for the identification of authenticity, and protection of the origin of local certified products. [ABSTRACT FROM AUTHOR]

Introduction: Elymus nutans holds ecological and pastoral significance due to its adaptability and nutritional value, the Qinghai-Tibet Plateau (QTP) is a key hub for its genetic diversity. To conserve and harness its genetic resources in highland ecosystems, a thorough assessment is vital. However, a comprehensive phylogeographic exploration of E. nutans is lacking. The objective of this study was to unravel the genetic diversity, adaptation, and phylogenetics of E. nutans populations. Methods: Encompassing 361 individuals across 35 populations, the species' genetic landscape and dynamic responses to diverse environments were decoded by using four chloroplast DNA (cpDNA) sequences and nine microsatellite markers derived from the transcriptome. Results and discussion: This study unveiled a notable degree of genetic diversity in E. nutans populations at nuclear (I = 0.46, He = 0.32) and plastid DNA levels (Hd = 0.805, π = 0.67). Analysis via AMOVA highlighted genetic variation predominantly within populations. Despite limited isolation by distance (IBD), the Mekong-Salween Divide (MSD) emerged as a significant factor influencing genetic differentiation and conserving diversity. Furthermore, correlations were established between external environmental factors and effective alleles of three EST-SSRs (EN5, EN57 and EN80), potentially linked to glutathione S-transferases T1 or hypothetical proteins, affecting adaptation. This study deepens the understanding of the intricate relationship between genetic diversity, adaptation, and environmental factors within E. nutans populations on the QTP. The findings shed light on the species' evolutionary responses to diverse ecological conditions and contribute to a broader comprehension of plant adaptation mechanisms. [ABSTRACT FROM AUTHOR]

Cotton is a major source of natural fibre for the global textile industry and is also an important oilseed crop. Cotton fibre is the main source of textiles, the seeds are used for oil and the remaining bagasse is used as high-protein animal feed. In addition, cotton's so-called short fibre is used in more than 50 industries. Cotton breeding is generally based on crossing the best yielding and fibre quality genotypes. However, cotton breeding programmes are negatively affected by the narrow genetic diversity of varieties. It is for this reason that the identification of genetic resources and the disclosure of genetic diversity are so important. Here, the genetic diversity of G. hirsutum and G. barbadense genotypes was determined using high-resolution capillary gel electrophoresis. Using 19 EST-SSR markers, a total of 47 genotypes were screened. The PIC values of the markers used ranged from 0.268 to 0.889. The mean PIC value was calculated to be 0.603. In terms of clustering, PCoA and population structure analyses gave similar results, and the genotypes could be divided into three main groups. Genetic admixture with G. hirsutum was found in some genotypes of the G. barbadense species. We can conclude that (i) the EST-SSR markers used in this study are effective in the determination of genetic diversity, (ii) the genetic diversity should be increased through the collection of genetic resources and (iii) the genetic EST-SSR markers in this study should be considered in breeding programmes by using them in QTL studies. [ABSTRACT FROM AUTHOR]

The velvetbean caterpillar Anticarsia gemmatalis (VBC) is widely distributed in the Americas and causes severe damage to soybean foliage. This insect presents high ecological plasticity, a feature that is of great importance to understand its genetic diversity and potential gene flow to assist in resistance management strategies. With this objective, we developed microsatellite markers for VBC and applied them to five populations from Brazil. Nine primers were polymorphic, with high values of polymorphic information content (PIC > 0.5), and 134 alleles were identified in 155 individuals. These primers indicated deviation from the Hardy–Weinberg equilibrium for all populations (observed heterozygosity, Ho = 0.48, expected heterozygosity, He = 0.76), with moderate to high levels of genetic diversity and a moderate fixation index (FST = 0.14) among the populations. Analysis of population structure indicated the formation of two principal clusters. The northern one can be divided into the two populations that formed the cluster, with high genetic differentiation between them. The other cluster is formed by three populations, and we found evidence of low gene flow between them in the south–north direction, indicating that these populations may be migratory in certain conditions. These findings indicate that the designed primers were effective in describing the genetic diversity of VBC, with major implications for integrated pest management. Given the little gene flow and the high genetic diversity of populations, they present great potential to become resistant to control practices, which can lead to increased management costs. [ABSTRACT FROM AUTHOR]

Kenaf is one of the most important natural cannabis plants. Molecular marker-assisted breeding is vital for accelerating the breeding process of kenaf. However, the number of kenaf markers is insufficient for molecular marker-assisted breeding. Using transcriptome sequencing data for salt-stressed kenaf plants, the number and distribution of simple sequence repeats (SSRs) and single nucleotide variations (SNVs) in the expressed sequences were determined. The objectives of this study were to elucidate the sequence variations in kenaf genes expressed in response to salt stress and to identify stable and dependable molecular markers. Primers were designed for SSR loci and then EST-SSR molecular markers were generated. The subsequent analyses revealed that 30.50% of the unigenes contained SSR motifs, most of which were single nucleotides followed by trinucleotides and dinucleotides. The unigenes containing SSRs were mostly associated with kenaf salt tolerance. Additionally, 10,483 SNVs were detected in contig sequences. Of the 3995 differentially expressed genes encoding interacting proteins, 1297 contained SSRs. Most of these genes were associated with metabolic pathways (e.g., 03000 transcription factors, B09132 signal transduction, and 04122 sulfur relay system). We designed 20 pairs of EST-SSR primers to genotype 30 kenaf varieties (lines), of which 9 primer pairs were ideal for genotyping (e.g., 1 highly polymorphic marker and 2 moderately polymorphic markers). The primer pairs designed for the EST-SSR markers in the kenaf genome may be useful SSR molecular markers for future research on kenaf. The verified polymorphic markers may be applicable to the molecular marker-assisted breeding of salt-tolerant kenaf varieties. [ABSTRACT FROM AUTHOR]

【Objective】 The study aimed to explore the SSR locus and distribution characteristics of Codonopsis tangshen Oliv transcriptome. 【Method】 Transcriptome sequencing was performed on C.tangshen leaves. The SSR locus of the transcriptome sequence was identified by MISA software, and functional annotation was performed on the Unigenes containing the SSR locus. Primer 3.0 was used to design EST-SSR primers, and the amplification stability of EST-SSR primers was verified based on C.tangshen germplasm from different regions. 【Result】 A total of 124 179 Unigenes were identified from the transcriptome sequences of C.tangshen, of which 26 084 Unigenes contained 35 827 SSR locus, with a SSR occurrence frequency of 21.01%.There were 165 types of SSR repeat elements in these SSR locus. From the distribution ratio of repeat elements in all the SSRs, the single nucleotide repeat elements A/T accounted for the highest percentage of 37.59%. In respect of the average distance of nucleotide repeat units, pentanucleotide showed the largest distance of 1288.54 kb. Concerning the proportion of primitive repetition times, the SSRs with that of ten accounted for the largest percentage of 21.55% (7722). The base count of SSR sequences was concentrated between 12 and 19 bp, with a total of 19 628 sequences (54.79%). There were 6933 potential polymorphic SSRs above 20 bp, accounting for 19.35% of all.27 SSR primers with stable amplification were selected to amplify the genomic DNA of C.tangshen, with the amplified fragment size ranging from 124 to 393 bp. Based on germplasm resources from different regions of C.tangshen, partial polymorphic markers with clear bands were selected. In addition, 26 084 Unigenes containing SSR locus were annotated by Go and KEGG analysis. These genes were highly enriched in biological processes such as transcriptional regulation, DNA binding, catalysis, and signal transduction. 【Conclusion】 SSR locus of C.tangshen transcriptome have high potential polymorphism, and developed potential polymorphic SSR markers will be used in research on genetic diversity analysis, germplasm identification, molecular assisted breeding, etc. of C.tangshen. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Agronomy is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wheat leaf rust, caused by Puccinia triticina, is one of the most important fungal diseases of wheat in China. However, little is known about the dynamic changes of population structure and genetic diversity of P. triticina during a period of time. In this study, 247 isolates of P. triticina collected from Hebei Province from 2001 to 2010 were tested on 36 Thatcher near-isogenic lines for virulence diversity and detected by 21 pairs of Expressed Sequence Tag derived Simple Sequence Repeat (EST-SSR) primers for genetic diversity. A total of 204 isolates were successfully identified as 164 races, and THTT, THST, PHRT, THTS, and PHTT were the most common races in Hebei Province from 2001 to 2010. The cluster analysis based on virulence showed that P. triticina has a rich virulence polymorphism, which had a certain correlation with the years, while the cluster analysis based on EST-SSR showed that the genetic diversity of the P. triticina population was significantly different between years in Hebei Province from 2001 to 2010. In addition, the population structure of P. triticina may have changed greatly in 2007 and 2009, which was significantly different from that of 2001–2006 on either virulence or genetic characteristics. The variation frequency of the population structure had an increasing trend during this period. From 2001 to 2010, there was a certain degree of gene flow among the P. triticina populations. No significant correlation was found between virulence and molecular polymorphism. The genetic differentiation analysis of the 10 tested populations (each year as a population) showed that the coefficient of genetic differentiation (Gst) was 0.27, indicating that there was a certain genetic differentiation among or within populations of P. triticina in Hebei Province. The genetic variation within populations (73.08%) was higher than that among populations (26.92%), which indicated that the genetic variations were mainly found within populations. Our study provides the foundation for a better understanding of the population structure change and genetic diversity of P. triticina over a period in Hebei Province of China. [ABSTRACT FROM AUTHOR]

Chrysosplenium macrophyllum Oliv., belonging to the family Saxifragaceae, is a traditional and unique Chinese herbal medicine. However, the lack of adequate molecular markers has hampered the progress regarding population genetics and evolution within this species. In this research, we used the DNBSEQ-T7 Sequencer (MGI) sequencing assay to analyze the transcriptome profiles of C. macrophyllum. SSR markers were developed on the basis of transcriptomic sequences and further validated on C. macrophyllum and other Chrysosplenium species. The genetic diversity and structure of the 12 populations were analyzed by using polymorphic expressed sequence tag simple sequence repeat (EST-SSR) markers. A potential pool of 3127 non-redundant EST-SSR markers were identified for C. macrophyllum in this study. The developed EST-SSR markers had high amplification rates and cross-species transferability in Chrysosplenium. Our results also showed that the natural populations of C. macrophyllum had a high level of genetic diversity. Genetic distance, principal component analysis, and popular structure analysis revealed that all 60 samples clustered into two major groups that were consistent with their geographical origins. This study provided a batch of highly polymorphic EST-SSR molecular markers that were developed via transcriptome sequencing. These markers will be of great significance for the study of the genetic diversity and evolutionary history of C. macrophyllum and other Chrysosplenium species. [ABSTRACT FROM AUTHOR]

Eastern black walnut (Juglans nigra L.), one of the most valuable timber and veneer trees in North America, provides nut shells with unique industrial uses and nut kernels with distinctive culinary attributes. A mature F1 full-sib progeny orchard of 248 individuals from the cross of two eastern black walnut cultivars provides a long-term resource for discovering genetic mechanisms controlling life history, quality traits, and stress resistance. The genetic linkage map, constructed with 356 single nucleotide polymorphism (SNP) markers and 62 expressed sequence tag simple sequence repeats (EST-SSRs), is 1645.7 cM in length, distributed across the expected 16 linkage groups. In this first application of QTL mapping in J. nigra, we report QTL for budbreak, peak pistillate bloom, peak staminate bloom, and heterodichogamy. A dominant major QTL for heterodichogamy is reported, the sequence for which is syntenic with the heterodichogamy QTL on chromosome 11 of Persian walnut (J. regia L.). The mapping population parents are both protogynous, and segregation suggests a Mendelian component, with a 3:1-like inheritance pattern from heterozygous parents. Mapping the sequenced EST-SSR markers to the J. regia "Chandler" V2.0 genome sequence revealed evidence for collinearity and structural changes on two of the sixteen chromosomes. The inclusion of sequenced EST-SSR markers enables the direct comparison of this and subsequent J. nigra maps and other Juglandaceae genetic maps. This investigation initiates long-term QTL detection studies for quality and stress resistance traits in black walnut. [ABSTRACT FROM AUTHOR]

The plant Camellia fascicularis , belonging to family Theaceae, has high ornamental and medicinal value, and rare gene resources for genetic improvement of Camellia crops, but is currently threatened with extinction because of the unique and extremely small wild populations. Molecular markers have clarified the wild plant species' genetic diversity structure, new gene resources and relationship with crops. This will be beneficial for conservation of these valuable crop-related wild species and crop improvement. In this study, we identified 95,979 microsatellite loci from 155,011 transcriptome unigenes, and developed 14 polymorphic expressed sequence tag-derived simple sequence repeat (EST-SSR) microsatellite markers for C. fascicularis. The number of alleles (Na) per locus was 2–8 with a mean of 4.86. The genetic diversity of 40 individuals from four natural populations of C. fascicularis was analysed using these polymorphic markers. The number of alleles (Na) for EST-SSR ranged from 2 to 5, with the expected heterozygosities (He) and observed heterozygosities (Ho) in all loci ranging from 0.183 to 0.683, and from 0.201 to 0.700, respectively, implying a rich genetic variation present in wild C. fascicularis populations. Moreover, the phylogenetic analysis among four populations, using the 14 EST-SSR markers developed in this study, grouped 40 individuals into three groups, which coincide with their geographic distribution. These results showed that 14 EST-SSR markers are available for the analysis of genetic variation in C. fascicularis populations and genetic improvement of new Camellias cultivars by interspecific hybridization, and are beneficial for conservation of the endangered species. [ABSTRACT FROM AUTHOR]

Pistacia chinensis Bunge (P. chinensis), a dioecious plant species, has been widely found in China. The female P. chinensis plants are more important than male plants in agricultural production, as their seeds can serve as an ideal feedstock for biodiesel. However, the sex of P. chinensis plants is hard to distinguish during the seedling stage due to the scarcity of available transcriptomic and genomic information. In this work, Illumina paired-end RNA sequencing assay was conducted to unravel the transcriptomic profiles of female and male P. chinensis flower buds. In total, 50,925,088 and 51,470,578 clean reads were obtained from the female and male cDNA libraries, respectively. After quality checks and de novo assembly, a total of 83,370 unigenes with a mean length of 1.3 kb were screened. Overall, 64,539 unigenes (77.48%) could be matched in at least one of the NR, NT, Swiss-Prot, COG, KEGG, and GO databases, 71 of which were putatively related to the floral development of P. chinensis. Additionally, 21,662 simple sequence repeat (SSR) motifs were identified in 17,028 unigenes of P. chinensis, and the mononucleotide motif was the most dominant type of repeats (52.59%) in P. chinensis, followed by dinucleotide (22.29%), trinucleotide (20.15%). The most abundant repeats were AG/CT (13.97%), followed by AAC/GTT (6.75%) and AT/TA (6.10%). Based on these SSR, 983 EST-SSR primers were designed, 151 of which were randomly chosen for validation. Of these validated EST-SSR markers, 25 SSR markers were found to be polymorphic between male and female plants. One SSR marker, namelyPCSSR55, displayed excellent specificity in female plants, which could clearly distinguish between male and female P. chinensis. Altogether, our findings not only reveal that the EST-SSR marker is extremely effective in distinguishing between male and female P. chinensis but also provide a solid framework for sex determination of plant seedlings. [ABSTRACT FROM AUTHOR]

Abelmoschus esculentus is a medicinal and edible plant that contains large amounts of active ingredients, including anthocyanins, polysaccharides, flavonoids, and terpenoids. However, because of a relative lack of molecular research, there are few molecular markers applicable for this plant species. In this study, on the basis of A. esculentus fruit color-related transcriptome sequencing data, we analyzed the patterns of simple sequence repeats (SSRs) in differentially expressed genes (DEGs) and revealed the biological processes and metabolic pathways associated with the related genes. We also designed primers for SSR loci to develop SSR molecular markers. Primers were synthesized using a DEG associated with a protein–protein interaction network. Polymorphic SSR markers were screened for the subsequent examination of A. esculentus germplasm resources and fruit color association analysis. The results indicated that 24.98% of the unigenes contained SSR motifs. Single-base (mononucleotide) repeats were the main SSRs, followed by trinucleotide and dinucleotide repeats. We selected 47 expressed sequence tag (EST)-SSR primer pairs for the genotyping of 153 A. esculentus varieties/lines. We ultimately obtained 21 EST-SSR markers suitable for genotyping. A generalized linear model-based association analysis detected two EST-SSR markers significantly associated with A. esculentus fruit color. In conclusion, several EST-SSR and SSR molecular markers in A. esculentus were developed in this study. The fruit color-associated markers may be useful for the molecular marker-assisted breeding of new A. esculentus varieties. [ABSTRACT FROM AUTHOR]

Copyright of Saffron Agronomy & Technology is the property of Torbat-e-Heydarie University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Psathyrostachys juncea is a perennial forage grass which plays an important role in soil and water conservation and ecological maintenance in cold and dry areas of temperate regions. In P. juncea , a variety of biotic and abiotic stress related genes have been used in crop improvement, indicating its agronomic, economic, forage, and breeding value. To date, there have been few studies on the genetic structure of P. juncea. Here, the genetic diversity and population structure of P. juncea were analyzed by EST-SSR molecular markers to evaluate the genetic differentiation related to tillering traits in P. juncea germplasm resources. The results showed that 400 simple sequence repeat (SSR) loci were detected in 2,020 differentially expressed tillering related genes. A total of 344 scored bands were amplified using 103 primer pairs, out of which 308 (89.53%) were polymorphic. The Nei's gene diversity of 480 individuals was between 0.092 and 0.449, and the genetic similarity coefficient was between 0.5008 and 0.9111, with an average of 0.6618. Analysis of molecular variance analysis showed that 93% of the variance was due to differences within the population, and the remaining 7% was due to differences among populations. Psathyrostachys juncea materials were clustered into five groups based on population genetic structure, principal coordinate analysis and unweighted pair-group method with arithmetic means (UPGMA) analysis. The results were similar between clustering methods, but a few individual plants were distributed differently by the three models. The clustering results, gene diversity and genetic similarity coefficients showed that the overall genetic relationship of P. juncea individuals was relatively close. A Mantel test, UPGMA and structural analysis also showed a significant correlation between genetic relationship and geographical distribution. These results provide references for future breeding programs, genetic improvement and core germplasm collection of P. juncea. [ABSTRACT FROM AUTHOR]

Zelkova schneideriana Hand.-Mazz. of the Ulmaceae family is a Tertiary relict and economically deciduous tree species endemic to Central and Southern China. In this study, we performed a transcriptome sequencing of Z. schneideriana using high-throughput sequencing approach to detect polymorphic expressed sequence tag-simple sequence repeats (EST-SSR) markers. A total of 3,235 microsatellite loci were detected from 53,517 unigenes. A set of 30 microsatellite markers were randomly selected to validate in 41 individuals from three populations, of which 10 were polymorphic. The number of alleles per locus ranged from 3 to 11. The observed heterozygosity and expected heterozygosity ranged from 0.366 to 0.829 and 0.439 to 0.848, respectively. These polymorphic SSR primers showed good transferability across different Zelkova species, and are valuable for future studies on genetic diversity, conservation, phylogeography, and species delimitation in Z. schneideriana, as well as other Zelkova species. [ABSTRACT FROM AUTHOR]

Colletotrichum fructicola causes strawberry anthracnose, which results in considerable economic losses in quality and production in Asia. However, the molecular mechanism of strawberry infection with C. fructicola is still poorly understood. Here, we employed RNA-Seq technology to mine the strawberry transcriptome for EST-SSRs (Expressed Sequence Tag–Simple Sequence Repeats) following C. fructicola infection. Fortunately, we detected 3019 potential EST-SSRs from the transcriptomic data of cv. Jiuxiang. The seven commonly occurring repeat motifs were A/T (278), GAA/TTC (263), GAG/CTC (215), AAG/CTT(188), GGA/TCC (163), AGA/TCT (153) and AGG/CCT (153). We identified 31, 84 and 129 differentially expressed EST-SSR-containing sequences corresponding to 24, 72 and 96 Hpi, while 13 DE-EST-SSRs -containing sequences were differentially expressed and common for all the three time points. Furthermore, we identified allele polymorphisms for some DE-EST-SSRs among several resistant and susceptible strawberry varieties and wild species. The EST-SSRs in our research were related to the reported QTL resistance loci in strawberry which are differentially expressed after C. fructicola infection and have allele polymorphisms in different strawberry varieties and wild species. These provide a clue for utilisation of the EST-SSRs in marker-assisted breeding to improve anthracnose-resistant breeding in future. [ABSTRACT FROM AUTHOR]

A factorial mating population between 10 Eucalyptus urophylla S. T. Blake and 10 E. tereticornis Smith parents tested at two sites was used to investigate the relationship of parental genetic variation to hybrid mean value (MV), specific hybridizing ability (SHA), and heterosis. Based on 184 polymorphic expressed sequence tag (EST) derived simple sequence repeats (SSR) markers, genetic distance (GD) between parents (GDAll) ranged from 0.293 to 0.783, averaging at 0.700. For tree height, breast-high diameter and wood density at age of 7.5 years, GDAll, GDs based on markers beyond 0.70 and 0.80 in polymorphism information content and GDs based on alleles within 0.10–0.90, 0.20–0.80, and 0.30–0.70 in allele frequency were not significantly correlated with MV, SHA, and the majority of heterosis types. GD based on effect-significant alleles was significantly correlated only with a few of traits or for certain site, while GDs based on effect-increasing (GDIA) and effect-decreasing alleles (GDDA) had significantly positive and negative correlations, respectively, with all the MV and SHA as well as across-site mid-parent heterosis. These results suggest the potential utility of GDIA and GDDA for molecular prediction of hybrid performance, SHA, and heterosis in Eucalyptus and may have implications for hybrid breeding in other plants. [ABSTRACT FROM AUTHOR]

High-quality simple sequence repeat (SSR) markers are invaluable tools for revealing genetic variability which could be utilized for many purposes, such as breeding new varieties or the identifying current ones, among other applications. Based on the analysis of 3.7 million EST sequences and 15 genomic sequences from bacterial artificial chromosome (BAC) libraries, 200 trinucleotide genic (EST)-SSR and three genomic (gSSR) markers were tested, where 17 of them fulfilled all criteria for quality markers. Moreover, the reproducibility of these new markers was verified by two genetics laboratories, with a mean error rate per allele and per locus equal to 0.17%. These markers were tested on 38 accessions of Papaver somniferum and nine accessions of another five species of the Papaver and Argemone genera. In total, 118 alleles were detected for all accessions (median = 7; three to ten alleles per locus) and 88 alleles (median = 5; three to nine alleles per locus) within P. somniferum alone. Multivariate methods and identity analysis revealed high resolution capabilities of the new markers, where all but three pair accessions (41 out of 47) had a unique profile and opium poppy was distinguished from other species. [ABSTRACT FROM AUTHOR]

The range-wide genetic structure of the highly productive and valuable timber species Sequoia sempervirens (D. Don) Endl. is still insufficiently studied, although published data based on different genetic markers (nuclear and chloroplast microsatellites, AFLP, RFLP and isozymes) demonstrated relatively low population structure. However, more genetic markers are needed to increase the efficiency of population genetic studies in coast redwood. Therefore, we developed seven nuclear and five chloroplast microsatellite or simple sequence repeat (SSR) markers based on expressed sequence tags (ESTs) and the complete chloroplast genome sequence, respectively. All selected markers were tested in a range-wide sample representing trees from 16 locations. They are highly polymorphic microsatellite loci with the number of alleles ranging from 3 to 17, and the number of effective alleles from 1.1 to 2.48. Coast redwood is a hexaploid species, and its chloroplasts are paternally inherited. Therefore, the chloroplast SSR markers are especially useful for this species, because their genotyping is not affected by nuclear genome ploidy. Moreover, they showed high gene diversity for each locus within and across all populations and can be used to study range-wide population genetic structure, pollen-based gene flow and long-distance gene transfer. Coast redwood can propagate clonally, and nuclear polymorphic EST-SSRs can be used for clonal identification. They are linked with expressed genes and their variation can reflect variation in genes under selection, including those that could be potentially important for local adaptation of coast redwood considering the threat of climate change. [ABSTRACT FROM AUTHOR]

The article focuses on a study to find isolation and characterization of twenty-nine novel expressed sequence tag-simple sequence repeat (EST-SSR) markers in Siniperca undulata. Topics discussed include economic impact of Siniperca undulata, information on population genetic, extraction of Genomic DNA using TIANamp Genomic DNA Kit, and analysis of population genetic structure and gene flow.

The intertidal marine red alga Porphyra umbilicalis reproduces asexually in the Northwest Atlantic. We looked for population substructure among typical opencoastal and atypical estuarine habitats in seven asexual populations of P. umbilicalis from Maine to New Hampshire using eight expressed sequence tag-simple sequence repeats (EST-SSR) or microsatellite loci. Six genotypes were identified, four of which may represent recombinant genotypes from a recombination event that took place locally, or that took place prior to introduction to the Northwest Atlantic. Genotypic diversity was lowest in a population from Wiscasset, Maine, which inhabits an atypical habitat high in the intertidal zone of a bridge piling in an estuarine tidal rapid. Genotypic diversity was highest in the southernmost populations from New Hampshire; we identified two genotypes that were unique to the southernmost populations, and probably represent the most derived genotypes. We looked at genetic distances among populations in similar habitats, and found that populations were more closely related to their closest neighboring population than to a population in a similar habitat. We show that genotypic diversity within P. umbilicalis populations in the Gulf of Maine is relatively high and thus fits a model of high steady-state variation within asexual populations. [ABSTRACT FROM AUTHOR]

Polyporus umbellatus , known as Zhuling in China, is a well-known and important medicinal fungus in Asia. Although P. umbellatus is highly valued for its medicinal properties, the expressed sequence based (genetic) markers are unknown. High-throughput transcriptome sequencing provides large amounts of transcriptome data for gene discovery and the development of molecular markers. In this study, all 38,444 unigenes were used to screen the SSR loci. A total of 1527 primer pairs were designed for marker development. Tri-nucleotide repeat motifs were the most abundant type, with a frequency of 47.4%, followed by mono- (28.5%), di- (21.1%), tetra- (0.16%), hexa- (0.1%) and penta-nucleotide repeat motifs (0.05%). A total of 50 primer pairs were synthesized, of which 31 (62%) yielded PCR amplification products. Eight individuals were used to examine amplifications and polymorphisms for all 50 loci. In eight P. umbellatus accessions, eight markers were polymorphic. To describe the genetic diversity and genetic relationship of P. umbellatus , the genotypes of 42 accessions representing diverse wild genotypes of P. umbellatus were analyzed. The number of alleles per locus varied from 7 to 13 alleles, and the genetic diversity values ranged from 0.345 to 0.785. We performed genetic diversity analysis using these 8 polymorphic markers. A UPGMA dendrogram was constructed based on Jaccard's similarity coefficients, revealing distinct clusters among the 42 accessions. This comprehensive set of genic SSR markers developed in our study is powerful and suitable for genetic analysis. [ABSTRACT FROM AUTHOR]

Microsatellite or Simple Sequence Repeat (SSR) markers have evolved to the status of a most versatile and popular genetic marker in a ubiquity of plant systems. Due to their co-dominant, hyper-variable and multiallelic nature, they are the prominent markers of choice for fingerprinting, conservation genetics, plant breeding and phylogenetic studies. Despite its development of a new set of SSR markers for a species remained time consuming and expensive for many years. However, with the recent advancement in genomics, new strategies/protocols are now available for the generation of SSR markers. This review presents an overview on microsatellite markers with a special emphasis on the various strategies used for the development of microsatellite markers. [ABSTRACT FROM AUTHOR]

A set of 33 wheat EST-SSR markers was designed and 18 from them were polymorphic and used for assessment of genetic diversity within 36 introduced genotypes of hexaploid bread wheat. Altogether 105 alleles were detected, in average 3.18 alleles per locus. Maximum number of alleles 14 was detected at the locus TDI389708. Five the most polymorphic markers were used for the evaluation and comparison of genetic variation within 46 domestic (Slovak) wheat genotypes and 36 introduced (foreign) wheat genotypes. The number of alleles per used primer pair within domestic genotypes varied from 7 to 19, with an average of 13.2 alleles, an average gene diversity 0.846 and PIC 0.980 per locus. The number of alleles per primer within introduced genotypes varied from 7 to 14, with an average of 10.8 alleles, an average gene diversity 0.780 and PIC 0.958 per locus. The level of polymorphism in EST- SSRs was sufficient for discrimination between genotypes and variation within domestic genotypes was slightly higher than in introduced genotypes. Variation revealed by 5 selected EST-SSR markers clustered genotypes according to origin. Domestic and introduced wheats were grouped distinctly into two separate groups. [ABSTRACT FROM AUTHOR]

With 1 figure and 1 table Abstract The availability of a large set of molecular markers is an excellent resource for both applied and basic research for any organism. The current consensus molecular map of pea is 1430 cM and contains 239 simple sequence repeat markers. The goal was to identify and test unique gene-based simple sequence repeat markers to increase the available number for comparative mapping with sequenced legume species. A total of 6327 mRNA sequences were screened using a JAVA algorithm, culminating in the design of 96 novel, gene-based simple sequence repeat markers. The markers were tested for polymorphism between the parents of two recombinant inbred line mapping populations (Early Freezer 680 × PI 269818 and C580257A × 74SN3A) and 11 additional pea lines. A total of 45 new EST-SSR polymorphic markers were identified using these test lines, another 35 were monomorphic and the remaining 16 failed or produced substandard amplification profiles. Linkage map locations are presented for seven of the new EST-SSR markers. Primer sequence, repeat type, status within tested genotypes and the SSR-finding algorithm are presented. [ABSTRACT FROM AUTHOR]