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Microsatellites, also known as SSR or STR, are essential molecular markers in genomic research, playing crucial roles in genetic mapping, population genetics, and evolutionary studies. Their applications range from plant breeding to forensics, highlighting their diverse utility across disciplines. Despite their widespread use, traditional methods for SSR analysis are often laborious and time-consuming, requiring significant resources and expertise. To address these challenges, a variety of computational tools for SSR analysis have been developed, offering faster and more efficient alternatives to traditional methods. However, selecting the most appropriate tool can be daunting due to rapid technological advancements and the sheer number of options available. This study presents a comprehensive review and analysis of 74 SSR tools, aiming to provide researchers with a valuable resource for SSR analysis tool selection. The methodology employed includes thorough literature reviews, detailed tool comparisons, and in-depth analyses of tool functionality. By compiling and analyzing these tools, this study not only advances the field of genomic research but also contributes to the broader scientific community by facilitating informed decision-making in the selection of SSR analysis tools. Researchers seeking to understand SSRs and select the most appropriate tools for their projects will benefit from this comprehensive guide. Overall, this study enhances our understanding of SSR analysis tools, paving the way for more efficient and effective SSR research in various fields of study. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a globally significant fungal disease that seriously threatens wheat yield, particularly in China. This study investigates the genetic structure and reproductive patterns of Pst populations in Ili, Xinjiang, using 12 pairs of Simple Sequence Repeat (SSR) molecular markers. Analyses of 79 Pst isolates from either spring or winter wheat areas in Ili revealed three primary genetic clusters, indicating notable differences between populations associated with spring and winter wheat. The STRUCTURE results, complemented by UPGMA and PCoA analyses, highlight significant genetic diversity within these populations, with evidence of genetic recombination and sexual reproduction in certain areas. Pst populations in Ili exhibit a mixed mode of reproduction, predominantly sexual in Qapqal and Xinyuan D and primarily asexual within the spring wheat populations. The gene flow analysis underscores extensive inter-population communication, which facilitates the spread and adaptation of the pathogen across diverse wheat-growing environments. This study marks the first documentation of sexual reproduction in Pst within Xinjiang, providing new insights into its spread and genetic variation. These findings suggest that sexual reproduction may play a role in the regional adaptation and evolution of Pst, impacting future management strategies for wheat stripe rust in Xinjiang and potentially in broader Central Asian contexts. [ABSTRACT FROM AUTHOR]

The Amazonian shrub Myrciaria dubia (camu-camu) produces vitamin C-rich fruits of growing commercial interest. However, sustainable utilization requires assessment and protection of the genetic diversity of the available germplasm. This study aimed to develop and apply microsatellite markers to assess genetic diversity and construct a core collection of M. dubia germplasm from the Peruvian Amazon. Sixteen polymorphic microsatellite loci were developed using an enrichment approach. The evaluation of 336 genotypes from 43 accessions of the germplasm bank, originating from eight river basins, was conducted using these newly developed markers. Genetic diversity parameters, including observed and expected heterozygosity, were calculated. Analysis of molecular variance (AMOVA) was performed to assess the distribution of genetic variation within and among accessions and river basins. Bayesian clustering analysis was employed to infer population structure. A core collection was constructed to maximize allelic richness. High genetic diversity was observed, with heterozygosity values ranging from 0.468 to 0.644 (observed) and 0.684 to 0.817 (expected) at the river basin level. AMOVA indicated significant genetic variation within (73–86%) compared to among (14–27%) accessions and river basins. Bayesian clustering detected ten genetic clusters, with several degrees of admixture among river basins, except for the genetically homogeneous Putumayo River basin. A core collection comprising 84 plant genotypes (25% of the full collection) was established, representing 90.82% of the overall allelic diversity. These results have important implications for M. dubia conservation strategies and breeding programs, in demonstrating a need for genetic connectivity between populations but preserving unique genetic resources in isolated basins. These results validate the expected levels of diversity and population subdivision in a crop and stress the need to secure genetically diverse germplasms, underscoring the importance of thorough genetic characterization for ex situ germplasm management. [ABSTRACT FROM AUTHOR]

Interspecific hybridization between two different Brassicaceae species, namely Brassica rapa ssp. pekinensis (♀) (AA, 2n = 2x = 20) and genetically modified Brassica napus (♂) (AACC, 2n = 4x = 38), was performed to study the transmission of a herbicide resistance gene from a tetraploid to a diploid Brassica species. Initially, four different GM B. napus lines were used for hybridization with B. rapa via hand pollination. Among the F1 hybrids, the cross involving the B. rapa (♀) × GM B. napus (♂) TG#39 line exhibited the highest recorded crossability index of 14.7 ± 5.7. However, subsequent backcross progenies (BC1, BC2, and BC3) displayed notably lower crossability indices. The F1 plants displayed morphological characteristics more aligned with the male parent B. napus, with significant segregation observed in the BC1 generation upon backcrossing with the recurrent parent B. rapa. By the BC2 and BC3 generations, the progeny stabilized, manifesting traits from both parents to varying degrees. Cytogenetic analysis revealed a substantial reduction in chromosome numbers, particularly in backcrossing progenies. BC1 plants typically exhibited 21–25 chromosomes, while BC2 progenies showed 21–22 chromosomes, and by the BC3 generation, stability was achieved with an average of 20 chromosomes. SSR marker analysis confirmed the progressive reduction of C-genome regions, retaining minimal C-genome-specific bands throughout successive backcrossing. Despite the extensive elimination of C-genome-specific genomic regions, the glyphosate resistance gene from the male parent B. napus was introgressed into BC3 progenies, suggesting that the glyphosate resistance gene located and introgressed in A-chromosome/genome regions of the Brassica plants. [ABSTRACT FROM AUTHOR]

To better understand the structure and evolution of the genomes of four plant pathogenic species of Zymoseptoria, we analyzed the occurrence, relative abundance (RA), and density (RD) of simple sequence repeats (SSRs) in their whole genome and transcriptome sequences. In this study, SSRs are defined as repeats of more than 12 bases in length. The genome and transcriptome sequences of Zymoseptoria ardabiliae show the highest RA (201.1 and 129.9) and RD (3229.4 and 1928.2) of SSRs, while those of Zymoseptoria pseudotritici show the lowest RA (167.2 and 118.5) and RD (2482.2 and 1687.0). The majority of SSRs in the genomic and transcriptome sequences of species were trinucleotide SSRs, while dinucleotide SSRs were the least common. The most common trinucleotide motifs in the transcriptomic sequences across all species were those that encoded the amino acid arginine. As per our motif conservation study, Zymoseptoria tritici (12.4%) possessed the most unique motifs, while Z. pseudotritici (3.9%) had the fewest. Overall, only 38.1% of the motifs were found to be conserved among the species. Gene enrichment studies reveal that three of the species, Z. ardabiliae, Zymoseptoria brevis, and Z. pseudotritici, have SSRs in their genes related to cellular metabolism, while the remaining Z. tritici harbors SSRs in genes related to DNA synthesis and gene expression. In an effort to improve the genetic resources for the orphan species of pathogenic Zymoseptoria, a total of 73,134 primers were created. The genomic resources developed in this study could help with analyses of genetic relatedness within the population and the development of species-specific markers. [ABSTRACT FROM AUTHOR]

This work aimed to conduct a comparative analysis of the occurrence, relative density (RD) and abundance (RA) of simple sequence repeats (SSRs), within the genomic and transcriptomic sequences of four different isolates of Cryptococcus neoformans. Among the whole genome sequences, it was observed that the C. neoformans isolate JEC21 exhibited the most elevated RA (165.3) and RD (2471.8) of SSRs. Conversely, among the transcriptome sequences, the C. neoformans isolate KN99 displayed the greatest RA (145.5) of SSRs. Among the classes of SSRs, trinucleotide repeats exhibited a higher prevalence in both the genomic sequences (50%) and transcriptome sequences (65%) over other repeats. Motif conservation analysis among the isolates demonstrated that 41.1% of motifs were conserved among the isolates of C. neoformans. The study also found unique motifs that could potentially serve as molecular probes for the purpose of isolate identification. A total of 8117 primers were created for the isolates of Cryptococcus to enrich it with genomic resources. The genomic resources created in this study have the potential to aid in the diversity analysis and the creation of markers specific to individual isolates. [ABSTRACT FROM AUTHOR]

Abstract The study was designed to validate the previously reported 34 SSR markers using 78 chilli genotypes to detect significant trait specific markers as well as superior genotypes resistant to Phytophthora capsici root rot (PcRR). In this context, the identification of germplasm with higher yield per plant (YPP) leads to hype in stress tolerance index (STI) in genotypes, Chakwal3 (11.98), Greenfire (10.14), Advanta5017 (9.94) and Chakwal4 (7.8). The identified genotypes were also found as resistant and moderately resistant due to existence of below 50% of disease incidence. Moreover, biplot showed the interrelation of STI with YPP through the formation of acute angle by their respective vectors. In the current study, the markers Hpms1172 and CAMS177 was found significant for STI. However, the marker CAMS066 was found associated with relative cell injury, CA06g27450 with disease incidence and CAMS173 with relative leaf damage. The bright bands on gel pictures of significant markers showed the association of these markers with resistant genotypes i.e. Chakwal3, Advanta-5017 and Chakwal4 as well as with a single moderately resistant genotype i.e. Greenfire. The markerstudes confirmed the phenotypic data by showing association of markers i.e. Hpms1172 and CAMS177, r with stress tolerance index. The principal coordinate analysis aligned with the results obtained from marker-assisted selection. Thus, currently practiced marker assisted selection detected high yielding genotypes in PcRR disease stress condition that will be helpful in progressing breeding programs in chilli.

Genetic markers are powerful tools for understanding genetic diversity and the molecular basis of traits, ushering in a new era of molecular breeding in crops. Over the past 50 years, DNA markers have rapidly changed, moving from hybridization-based and second-generation-based to sequence-based markers. Simple sequence repeats (SSRs) are the ideal markers in plant breeding, and they have numerous desirable properties, including their repeatability, codominance, multi-allelic nature, and locus specificity. They can be generated from any species, which requires prior sequence knowledge. SSRs may serve as evolutionary tuning knobs, allowing for rapid identification and adaptation to new circumstances. The evaluations published thus far have mostly ignored SSR polymorphism and gene evolution due to a lack of data regarding the precise placements of SSRs on chromosomes. However, NGS technologies have made it possible to produce high-throughput SSRs for any species using massive volumes of genomic sequence data that can be generated fast and at a minimal cost. Though SNP markers are gradually replacing the erstwhile DNA marker systems, SSRs remain the markers of choice in orphan crops due to the lack of genomic resources at the reference level and their adaptability to resource-limited labor. Several bioinformatic approaches and tools have evolved to handle genomic sequences to identify SSRs and generate primers for genotyping applications in plant breeding projects. This paper includes the currently available methodologies for producing SSR markers, genomic resource databases, and computational tools/pipelines for SSR data mining and primer generation. This review aims to provide a 'one-stop shop' of information to help each new user carefully select tools for identifying and utilizing SSRs in genetic research and breeding programs. [ABSTRACT FROM AUTHOR]

The silkworm is an ideal lepidopteran model for the study of genetics and genetic diversity. In this study, inter-simple sequence repeats (ISSR) and Simple Sequence Repeats (SSRs) were used to investigate genetic relationships among 32 mulberry silkworm genotypes which included bivoltine and multivoltine silkworm breeds. Genomic DNA was isolated from the silkmoth samples and six polymorphic ISSRs were utilized to screen the genotypes. A total of 641 scorable alleles were identified among 32 silkworm genotypes utilizing six polymorphic ISSR markers and size ranged from ~ 100 to ~ 1400 bp. The percent polymorphism for six ISSR primers ranged from 46.15 to 63.63%. A total of six monomorphic alleles were observed, accounting for 8.57%. Similarly, three thermotolerant SSR markers were screened which revealed a total of 108 alleles with a polymorphism of 69.44%. The molecular mass of the alleles ranged from ~ 190 bp to ~ 250 bp. The chi square based similarity index represents a clear genetic similarity of the silkworm breeds BMV2 and BM22 (0.23) and the maximum genetic distance for breeds TMS knob and CSR27SL (1.32). Cluster dendrogram utilizing distance matrix classified the genotypes into two clusters with five sub clusters representing highest polymorphism with 21 genotypes. Thus, ISSRs and SSRs polymorphic markers are informative for estimating the extent of genetic diversity as well as to determine the pattern of genetic relationships between different silkworm genotypes and provide unique molecular identity based on the identified monomorphic bands. ISSR and SSR marker-based barcodes could be an effective tool for the selection of parentage in silkworm breeding programs. [ABSTRACT FROM AUTHOR]

Microsatellites, also known as SSR or STR, are essential molecular markers in genomic research, playing crucial roles in genetic mapping, population genetics, and evolutionary studies. Their applications range from plant breeding to forensics, highlighting their diverse utility across disciplines. Despite their widespread use, traditional methods for SSR analysis are often laborious and time-consuming, requiring significant resources and expertise. To address these challenges, a variety of computational tools for SSR analysis have been developed, offering faster and more efficient alternatives to traditional methods. However, selecting the most appropriate tool can be daunting due to rapid technological advancements and the sheer number of options available. This study presents a comprehensive review and analysis of 74 SSR tools, aiming to provide researchers with a valuable resource for SSR analysis tool selection. The methodology employed includes thorough literature reviews, detailed tool comparisons, and in-depth analyses of tool functionality. By compiling and analyzing these tools, this study not only advances the field of genomic research but also contributes to the broader scientific community by facilitating informed decision-making in the selection of SSR analysis tools. Researchers seeking to understand SSRs and select the most appropriate tools for their projects will benefit from this comprehensive guide. Overall, this study enhances our understanding of SSR analysis tools, paving the way for more efficient and effective SSR research in various fields of study.

Farmers in Garut, West Java, grow mixed varieties of Arabica coffee (Coffea arabica L.). Subsequently, they use harvested beans as seeds. Intercrossing among varieties may result in hybrid progenies and harvesting hybrid progenies as seed results in genetic variations. This research aims to evaluate the genetic diversity of Arabica coffee grown in a mixed population. Ninety-one Arabica coffees comprised 37 Arabica cv. “Ahernt GRT KN” (yellow-), 45 “Sigararutang” (red-), and nine “S795” (red berries) were sampled. Twenty SSR primer pairs were validated using 15 samples representing three varieties; six were polymorphic and used to genotype 91 Arabica accessions. Genetic data were analyzed using PowerMaker 3.25 and Darwin version 6 software. The results showed that the six SSR loci generated from 2 – 3 alleles, with an average of 2.17 alleles per locus. Genetic analysis of Arabica coffee from Garut, West Java, generated SSR markers with an average PIC of 0,33 across loci and varieties. The PIC within Arabica coffee cv. “Ahernt GRT KN” and “Sigararutang” were low, and within “S795” was moderate. Those PICs indicate the presence of more genetic diversity within “S795” than the other two cultivars. The Ho across Arabica coffee cv. “Sigararutang” and “S795” were lower than the He values, confirming their self-pollination nature. However, the Ho values of Arabica coffee cv. “Ahernt GRT KN” was larger than the others, indicating the presence of residual heterozygosity and a low percentage of recent outcrossing. The low Ho values of “Sigararutang” suggest that Arabica coffee is homozygous. Arabica coffee cv. “S795” also showed a low Ho value, but its moderate He value indicates the presence of more genetic diversity than the other cultivars.

Abstract Background Tandem repeats are specific sequences in genomic DNA repeated in tandem that are present in all organisms. Among the subcategories of TRs we have Satellite repeats, that is divided into macrosatellites, minisatellites, and microsatellites, being the last two of specific interest because they can identify polymorphisms between organisms due to their instability. Currently, most mining tools focus on Simple Sequence Repeats (SSR) mining, and only a few can identify SSRs in the coding regions. Results We developed a microsatellite mining software called SATIN (Micro and Mini SATellite IdentificatioN tool) based on a new sliding window algorithm written in C and Python. It represents a new approach to SSR mining by addressing the limitations of existing tools, particularly in coding region SSR mining. SATIN is available at https://github.com/labgm/SATIN.git . It was shown to be the second fastest for perfect and compound SSR mining. It can identify SSRs from coding regions plus SSRs with motif sizes bigger than 6. Besides the SSR mining, SATIN can also analyze SSRs polymorphism on coding-regions from pre-determined groups, and identify SSRs differentially abundant among them on a per-gene basis. To validate, we analyzed SSRs from two groups of Escherichia coli (K12 and O157) and compared the results with 5 known SSRs from coding regions. SATIN identified all 5 SSRs from 237 genes with at least one SSR on it. Conclusions The SATIN is a novel microsatellite search software that utilizes an innovative sliding window technique based on a numerical list for repeat region search to identify perfect, and composite SSRs while generating comprehensible and analyzable outputs. It is a tool capable of using files in fasta or GenBank format as input for microsatellite mining, also being able to identify SSRs present in coding regions for GenBank files. In conclusion, we expect SATIN to help identify potential SSRs to be used as genetic markers.

Background: Tandem repeats are specific sequences in genomic DNA repeated in tandem that are present in all organisms. Among the subcategories of TRs we have Satellite repeats, that is divided into macrosatellites, minisatellites, and microsatellites, being the last two of specific interest because they can identify polymorphisms between organisms due to their instability. Currently, most mining tools focus on Simple Sequence Repeats (SSR) mining, and only a few can identify SSRs in the coding regions. Results: We developed a microsatellite mining software called SATIN (Micro and Mini SATellite IdentificatioN tool) based on a new sliding window algorithm written in C and Python. It represents a new approach to SSR mining by addressing the limitations of existing tools, particularly in coding region SSR mining. SATIN is available at https://github.com/labgm/SATIN.git. It was shown to be the second fastest for perfect and compound SSR mining. It can identify SSRs from coding regions plus SSRs with motif sizes bigger than 6. Besides the SSR mining, SATIN can also analyze SSRs polymorphism on coding-regions from pre-determined groups, and identify SSRs differentially abundant among them on a per-gene basis. To validate, we analyzed SSRs from two groups of Escherichia coli (K12 and O157) and compared the results with 5 known SSRs from coding regions. SATIN identified all 5 SSRs from 237 genes with at least one SSR on it. Conclusions: The SATIN is a novel microsatellite search software that utilizes an innovative sliding window technique based on a numerical list for repeat region search to identify perfect, and composite SSRs while generating comprehensible and analyzable outputs. It is a tool capable of using files in fasta or GenBank format as input for microsatellite mining, also being able to identify SSRs present in coding regions for GenBank files. In conclusion, we expect SATIN to help identify potential SSRs to be used as genetic markers. [ABSTRACT FROM AUTHOR]

Introduction: The Cucurbitaceae family comprises many agronomically important members, that bear nutritious fruits and vegetables of great economic importance. Coccinia grandis, commonly known as Ivy gourd, belongs to this family and is widely consumed as a vegetable. Members of this family are known to display an impressive range of variation in fruit morphology. Although there have been studies on flower development in Ivy gourd, fruit development remains unexplored in this crop. Methods: In this study, comparative transcriptomics of two Ivy gourd cultivars namely "Arka Neelachal Kunkhi" (larger fruit size) and "Arka Neelachal Sabuja" (smaller fruit size) differing in their average fruit size was performed. A de novo transcriptome assembly for Ivy gourd was developed by collecting fruits at different stages of development (5, 10, 15, and 20 days after anthesis i.e. DAA) from these two varieties. The transcriptome was analyzed to identify differentially expressed genes, transcription factors, and molecular markers. Results: The transcriptome of Ivy gourd consisted of 155205 unigenes having an average contig size of 1472bp. Unigenes were annotated on publicly available databases to categorize them into different biological functions. Out of these, 7635 unigenes were classified into 38 transcription factor (TF) families, of which Trihelix TFs were most abundant. A total of 11,165 unigenes were found to be differentially expressed in both the varieties and the in silico expression results were validated through real-time PCR. Also, 98768 simple sequence repeats (SSRs) were identified in the transcriptome of Ivy gourd. Discussion: This study has identified a number of genes, including transcription factors, that could play a crucial role in the determination of fruit shape and size in Ivy gourd. The presence of polymorphic SSRs indicated a possibility for markerassisted selection for crop breeding in Ivy gourd. The information obtained can help select candidate genes that may be implicated in regulating fruit development and size in other fruit crops. [ABSTRACT FROM AUTHOR]

The present investigation unveiled the first complete chloroplast (cp) genome of Tribulus macropterus var. arabicus (Hosni) Al-Hemaid & J. Thomas (Zygophyllaceae), a medicinal herb, indigenous to Saudi Arabia. The cp genome, comprising a length of 158,179 bp and a GC content of 35.8%, exhibited the typical circular quadripartite arrangement of flowering plants, including two inverted repeat regions (25842 bp) separated by a large single-copy (88873 bp) and a small single-copy region (17622 bp). Genome annotation unraveled 132 genes, comprising of 87 protein-coding genes, 37 tRNAs and eight rRNAs. A comparative plastomics approach demonstrated a very similar genome structure and gene organization in closely related taxa. Whole-genome alignment indicated that the inverted repeat regions exhibited greater conservation when compared to the single copy zones. Repeat analysis of the cp genome identified 80 simple sequence repeats, with the majority (64) being mononucleotides. Among the longer repeats, forward repeats were frequent (20) followed by palindromic and reverse repeats. The nucleotide diversity endeavor identified some hypervariable sites (rpl22, cemA, trnLUAG) in the small and large single copies which would offer opportunities to design molecular markers for potential application in taxonomic identification. Phylogenetic analysis with rbcL barcode elucidated the distinct position of T. macropterus var. arabicus compared to T. macropterus within Zygophyllaceae and further validated the assembly. The findings of this investigation provide significant insights into biological fields, particularly enhancing the current understanding of the genetic and evolutionary variations within Zygophyllaceae. [ABSTRACT FROM AUTHOR]

Because the universe of possible DNA sequences is inconceivably vast, organisms have evolved mechanisms for exploring DNA sequence space while substantially reducing the hazard that would otherwise accrue to any process of random, accidental mutation. One such mechanism is meiotic recombination. Although sexual reproduction imposes a seemingly paradoxical 50% cost to fitness, sex evidently prevails because this cost is outweighed by the advantage of equipping offspring with genetic variation to accommodate environmental vicissitudes. The potential adaptive utility of additional mechanisms for producing genetic variation has long been obscured by a presumption that the vast majority of mutations are deleterious. Perhaps surprisingly, the probability for adaptive variation can be increased by several mechanisms that generate mutations abundantly. Such mechanisms, here called 'mutation protocols', implement implicit 'constraints that deconstrain'. Like meiotic recombination, they produce genetic variation in forms that minimize potential for harm while providing a reasonably high probability for benefit. One example is replication slippage of simple sequence repeats (SSRs); this process yields abundant, reversible mutations, typically with small quantitative effect on phenotype. This enables SSRs to function as adjustable 'tuning knobs'. There exists a clear pathway for SSRs to be shaped through indirect selection favouring their implicit tuning‐knob protocol. Several other molecular mechanisms comprise probable components of additional mutation protocols. Biologists might plausibly regard such mechanisms of mutation not primarily as sources of deleterious genetic mistakes but also as potentially adaptive processes for 'exploring' DNA sequence space. [ABSTRACT FROM AUTHOR]

The present study "Identification of heat tolerant bread wheat (Triticum aestivum L.)" genotypes through heat susceptibility index (HSI) and SSR markers" was undertaken by growing 52 genotypes during rabi 2019–20 and rabi 2020–21 in two different sowing conditions (timely sowing and late sowing). Based on pooled results of two years for heat susceptibility index (HSI) and yield stability ratio (YSR), eight genotypes, viz. AKAW 4901, UAS 375, K 1317, WH 1127, HTW 11, WH 1105, HIKK 09 and DBW 14 were identified as heat tolerant genotypes, as these genotypes had heat susceptibility index less than 0.50 and high yield stability ratio (> 83%) with less reduction in grain yield. The screening of all the genotypes was also carried out based on 14 heat tolerant specific SSR markers. Out of the total 14 SSR primers, 6 primers represented the A genome, 4 represented the B genome and the rest of the 4 were from the D genome of wheat. These primers detected 30 polymorphic alleles among the 52 wheat genotypes. The polymorphic information content (PIC) varied greatly between SSR primers and their value varied from 0.20 to 0.49. Cluster analysis using SSR data was determined for each pair of 52 genotypes by Jaccard's similarity coefficient, which revealed that the lowest similarity of 5 per cent was noticed between AKAW 4901 and DBW 246, while the highest of 88 per cent was noticed between DBW 179 and WH 1105 genotypes. Based on the HSI and molecular data analysis 6 genotypes, namely AKAW 4901, UAS 375, K 1317, HTW 11, WH 1105 and HIKK 09 were identified to be heat tolerant and are recommended for cultivation under late sown and rainfed environment. Furthermore, the result of molecular analysis coincides with the result of HSI, and hence in the future only molecular markers can be used to identify the tolerant genotypes rather than going for phenotyping in different environments. [ABSTRACT FROM AUTHOR]

Identification of markers associated with fertility restoration (Rf) genes is essential because they can streamline the breeding of new CMS lines and production of commercial hybrid seeds. Therefore, in the present study, F2 populations (M31‐2A × DSMR 8) was utilized to identify markers linked to Rf loci on maldandi (A4) cytoplasm through bulk segregant analysis (BSA). The F2 population was analysed for seed set percentage. Chi‐square (χ2) analysis showed that the fertility restoration trait followed expected digenic ratio. By BSA, simple sequence repeats (SSRs) markers, namely, Xtxp 34 and Xtxp 69 located on chromosome 3 and SB 3956 and Xtxp 312 located on chromosome 7, showed clear polymorphism between two groups of fertile and sterile bulks. The genomic region harbouring Rf locus on chromosome 3 (2.61 Mbp) predicted to encode five pentatricopeptide repeat (PPR) genes whereas, on chromosome 7, the gene SORBI_3007G047400 predicted to encode MYB (myeloblastosis) domain containing proteins. These predicted genes could be the candidate for restoring fertility on A4 cytoplasm. This finding will be fundamental in the production and rapid selection of novel restorer lines. [ABSTRACT FROM AUTHOR]

Tomato (Solanum lycopersicum L.) crop is well-known for its versatility worldwide and is also recognized as model species used extensively for various genetic studies. The aim of this research was to investigate both inter and intra-genetic diversity present among various tomato genotypes. This investigation was carried out through a comprehensive analysis encompassing morphological observations, biochemical assessments, and the utilization of SSR markers. A total of 15 discrete agro-morphological traits and six biochemical traits were undertaken in the current study for evaluating the analysis of variance, genetic parameters and correlation. The analysis of variance indicated significant differences across genotypes for all 15 agro-morphological traits and 6 biochemical traits tested, indicating that the experimental material included considerable variability. Morphological clustering divided the genotypes into 2 clusters and the genotype wise distance matrix was obtained to identify the most diverse genotypes. PCA analysis was conducted to understand the directive relation of traits and magnitude of variability contributed by them. SSR profiling with 24 primers identified 44 alleles with 1.83 as mean number of alleles/SSR with an average PIC value of 0.31. Structure analysis revealed two sub-populations (K = 2). The AMOVA indicated that 98% of the total variation was present within populations. This study presents a roadmap for composing future breeding strategies for integrating desirable traits in novel tomato lines that combine robustness and nutritive value. [ABSTRACT FROM AUTHOR]

Relying solely on cross-species analysis of single nucleotide polymorphisms (SNPs) through single-species genome mining can introduce biases. To address this challenge, we propose a sequencing-based approach for genome-wide genotyping of simple sequence repeats (SSRs) as an alternative method. Megalobrama, belonging to the family Xenocyprididae of the order Cypriniformes, comprises four primary species: M. amblycephala (Mambl), M. terminalis (Mterm), M. pellegrini (Mpell), and M. hoffmanni (Mhoff). This study employs a sequencing-based genome-wide SSR genotyping approach, analyzing genetic information from nine Megalobrama populations using SSRs extracted from the Mambl genome. Our genotyping efforts successfully covered 916 or 24,180 SSR loci, with less than 10% or 30% of missing data, respectively. The analysis reveals significant gene flow between Mterm, Mpell, and Mambl, validated by the D-statistic test. The F3-statistic values, estimated at -0.00868676 or -0.00831186 based on 916 or 24,180 SSR loci respectively, further support these findings. Additionally, the hypothesis of extensive gene flow among Mterm, Mambl, and Mpell gains robust support from Approximate Bayesian Computation, with a posterior probability of 0.674. Species trees and phylogenetic networks, constructed using 4,116 orthogroups identified across all species, corroborate this hypothesis. Importantly, our study emphasizes the suitability of genome-wide SSRs over SNPs for cross-species genetic diversity studies. In conclusion, our study contributes to the discourse of conservation genetics, advocating for a holistic approach that integrates diverse markers while recognizing their limitations. Our findings not only illuminate the genetic landscape of Megalobrama species but also offer guiding principles for conservation efforts. [ABSTRACT FROM AUTHOR]

Wood-apple (Limonia acidissima L., Rutaceae) is an underutilized fruit tree species in the Indian subcontinent. The edible fruit and other parts of the wood-apple tree have immense medicinal and nutritional properties. In this study, we used 24 polymorphic simple sequence repeats (SSRs), developed de novo through RNA sequencing, to estimate the genetic diversity and population structure in 96 wood-apple samples collected from 16 states of India. We identified 11,401 SSRs from 215,859 unigenes. The dinucleotide repeat motifs were the most abundant SSRs (56.89%), followed by trinucleotide (37.61%) and tetranucleotide repeats (3.63%). SSR profiling detected 129 alleles, with an average of 5.37 per locus and an average PIC value of 0.62. The Jaccard's genetic dissimilarity among 96 samples ranged from 0.39 to 1.0 (average 0.94 ± 0.03). Cluster analyses by Neighbour-joining (NJ) and principal coordinates analysis (PCoA) grouped all samples into three clusters. The Bayesian model-based structure analysis also identified three subpopulations. Population genetic analysis showed moderate gene diversity (0.226 ± 0.007) and Shannon's information index (0.369 ± 0.009) in the species. Analysis of molecular variance (AMOVA) revealed higher genetic variance within the populations than among populations, while the FST statistics (0.134, p < 0.010) indicated low but significant genetic differentiation. The overall results indicated moderate to high genetic diversity among wood-apple samples. This study identified 14 diverse samples and nine highly informative SSRs that could be useful for developing breeding programs to improve the species and conserve its genetic resources. [ABSTRACT FROM AUTHOR]

Simple sequence repeats (SSRs) are present across both coding & non-coding regions of the genomes of all organisms with diversity in incidence, complexity, and repetition. The present study is focused on Adenoviridae which are non-enveloped viruses consisting of linear double-stranded DNA genome. The members of Adenoviridae are known to cause respiratory illnesses like the common cold (cough, runny nose, mild fever), pneumonia (occasionally), keratoconjunctivitis (infection in the eye known as pink eye), croup and cystitis (inflammation of the bladder). Our investigation aims to extract and analyse SSRs from 68 Adenoviridae genomes. Virus genome sequences were retrieved from NCBI and SSRs extracted from MISA. ETE3 and iTOL were used for the phylogenetic tree construction, annotation and visualization. The genome length of Adenoviridae genomes ranged from 26163 bp to 45667 bp while GC content varied from 33.6 % to 66.9 %. Genome wide analysis revealed a total incidence of 9861 SSRs and 793 cSSRs. The minimum and maximum range of SSR incidence is 112 (A67) to 203 (A61) respectively. The most prevalent mono, di and tri-SSR motif is “A”, “GC/CG” and “GAG/CTC” comprised of 1177, 1859 and 201 occurrences respectively. About 78 % SSRs are present in the coding region in the studied genomes. In terms of protein specific distribution, DNA polymerase enzyme had the highest incidence of 485 SSRs. The presence of mono-SSRs in the A/T region is a marker for host determination and divergence. The average mono-SSRs present in A/T region is 67.14 % and it ranged from 16.22 % to 99.11 %. The high prevalence of mono-SSRs in the A/T region was associated with human and related species as hosts. Further, the clustering of viruses as per their hosts was observed in the phylogenetic tree suggesting the role of host in viral evolution. The presence of unique and conserved cSSRs as genome markers has also been highlighted.

Interspecific hybridization between two different Brassicaceae species, namely Brassica rapa ssp. pekinensis (♀) (AA, 2n = 2x = 20) and genetically modified Brassica napus (♂) (AACC, 2n = 4x = 38), was performed to study the transmission of a herbicide resistance gene from a tetraploid to a diploid Brassica species. Initially, four different GM B. napus lines were used for hybridization with B. rapa via hand pollination. Among the F1 hybrids, the cross involving the B. rapa (♀) × GM B. napus (♂) TG#39 line exhibited the highest recorded crossability index of 14.7 ± 5.7. However, subsequent backcross progenies (BC1, BC2, and BC3) displayed notably lower crossability indices. The F1 plants displayed morphological characteristics more aligned with the male parent B. napus, with significant segregation observed in the BC1 generation upon backcrossing with the recurrent parent B. rapa. By the BC2 and BC3 generations, the progeny stabilized, manifesting traits from both parents to varying degrees. Cytogenetic analysis revealed a substantial reduction in chromosome numbers, particularly in backcrossing progenies. BC1 plants typically exhibited 21–25 chromosomes, while BC2 progenies showed 21–22 chromosomes, and by the BC3 generation, stability was achieved with an average of 20 chromosomes. SSR marker analysis confirmed the progressive reduction of C-genome regions, retaining minimal C-genome-specific bands throughout successive backcrossing. Despite the extensive elimination of C-genome-specific genomic regions, the glyphosate resistance gene from the male parent B. napus was introgressed into BC3 progenies, suggesting that the glyphosate resistance gene located and introgressed in A-chromosome/genome regions of the Brassica plants.

Knowledge of the parental origin of crop species is a prerequisite for formulating effective strategies for genetic conservation, management, and utilisation of genotypes in breeding programmes and genetic studies. In the case of the potato, although pedigree information is well documented, the possible lack of accurate pedigree data for certain cultivars constitutes a loss of opportunity to exploit the selection gain, the precise targeting of a market niche, or other breeding objectives. In this study, the genetic profiles of 1249 varieties were examined using a set of 35 polymorphic simple sequence repeats (SSR) markers with the available pedigree information to achieve pedigree validation. The maximum likelihood (LOD) was used to validate pedigree information of potato accessions for which the genetic data of at least one parent was available in the dataset. Our results showed that among the accessions for which both parents were genotyped, 81.7% presented a validated pedigree, while 18.3% presented a pedigree conflict (for at least one parent). Among the accessions for which only one parent was available in the dataset, 91.3% presented a validated pedigree, while 8.7% presented a pedigree conflict. Then, pedigree reconstruction was investigated to determine the most likely parent candidates for varieties whose pedigree is either questionable or lacking information. [ABSTRACT FROM AUTHOR]

Feces of animals that forage on nectar and fruit, including many species of bats, often contain DNA that is low in quality and quantity. We developed an approach based on DNA from feces gathered passively to generate microsatellite data for individual lesser long-nosed bats (Leptonycteris yerbabuenae), which are important pollinators for columnar cacti and agave across much of Mexico and in the southwestern U.S. We collected feces from roosts near the U.S-Mexico border and developed a two-step amplification approach to characterize five highly polymorphic microsatellite loci from fecal DNA. Addition of a multiplex PCR step improved amplification success and conserved DNA extracts with a minimal increase in cost. In our initial screening of 433 samples, five focal loci distinguished individuals reliably, with a probability of identity (i.e., the probability of two unrelated individuals having the same microsatellite profile by chance) of 7.5E-09. Repeated analyses revealed a genotyping error rate < 2%. We explore the benefits and limits of our approach for population studies of lesser long-nosed bats and other nectivorous and frugivorous species that provide key ecosystem services and are often of conservation concern. [ABSTRACT FROM AUTHOR]

Crop wild relatives (CWR) represent valuable sources of traits that can enhance the abiotic and biotic stress tolerance of crops. Due to climate change and expansion of land use, they may suffer from population decline, which increases the risk of losing these resources. The in situ conservation of CWR is receiving growing attention to preserve their intraspecific diversity. In contrast to the safeguarding of seeds ex situ, the preservation of taxa in their natural habitat facilitates the development of new adaptations to changing environmental conditions. However, studies aiming at the establishment of their in situ conservation are rare. Therefore, we identified and genotyped Helosciadium nodiflorum occurrences in Germany. Helosciadium nodiflorum is an endangered CWR of cultivated celery (Apium graveolens). For 20 occurrences the number of individuals, the number of sexually reproducing individuals, and potential threats were recorded. Genetic differences were examined using 17 newly developed simple sequence repeats (SSR). Population genetic analyses, like the inference of the compositional genetic differentiation, of population structure, and a Discriminant Analysis of Principal Components were conducted. The analyses revealed that most occurrences were genetically distinct. Geographically closely located populations are often also genetically more similar. Several populations revealed a composite genome indicative of hybridizations between distinct populations. Populations that experienced fixation were also identified. Based on the genetic diversity, the location in different ecogeographic units, and the support of local stakeholders, we recommend the establishment of 15 genetic reserves for H. nodiflorum in Germany. [ABSTRACT FROM AUTHOR]

Introduction: Simple sequence repeats (SSR), also known as microsatellites, are crucial molecular markers in both animals and plants. Despite extensive previous research on SSRs, the development of microsatellite markers in Brassica crops remains limited and inefficient. Methods: Krait software was used to identify microsatellites by genome-wide and marker development based on three recently sequenced basic species of Brassica crops in the triangle of U (Brassica rapa, B. nigra and B. oleracea), as well as three allotetraploids (B. juncea, B. napus and B. carinata) using public databases. Subsequently, the primers and the characteristics of microsatellites for most of them were accordingly designed on each chromosome of each of the six Brassica species, and their physical locations were identified, and the cross-transferability of primers have been carried out. In addition, a B-genome specific SSR marker was screened out. Results: A total of 79341, 92089, 125443, 173964, 173604, and 222160 SSR loci have been identified from the whole genome sequences of Brassica crops within the triangle of U crops, B. rapa (AA), B. nigra (BB), B. oleracea (CC), B. napus (AACC), B. juncea (AABB) and B. carinata (BBCC), respectively. Comparing the number distribution of the three allotetraploid SSR loci in the three subgenomes AA, BB and CC, results indicate that the allotetraploid species have significant reduction in the number of SSR loci in the genome compared with their basic diploid counterparts. Moreover, we compared the basic species with their corresponding varieties, and found that the microsatellite characters between the allotetraploids and their corresponding basic species were very similar or almost identical. Subsequently, each of the 40 SSR primers was employed to investigate the polymorphism potential of B. rapa (85.27%), B. nigra (81.33%) and B. oleracea (73.45%), and B. rapa was found to have a higher cross-transfer rate among the basic species in the triangle of U. Meanwhile, a B-genome specific SSR marker, BniSSR23228 possessing the (AAGGA)3 sequence characteristics was obtained, and it located in chromosome B3 with a total length of 97 bp. Discussion: In this study, results suggest that the pattern of distribution may be highly conserved during the differentiation of basic Brassica species and their allotetraploid counterparts. Our data indicated that the allotetraploidization process resulted in a significant reduction in SSR loci in the three subgenomes AA, BB and CC. The reasons may be partial gene dominated chromosomal homologous recombination and rearrangement during the evolution of basic diploid species into allotetraploids. This study provides a basis for future genomics and genetic research on the relatedness of Brassica species. [ABSTRACT FROM AUTHOR]

In species that primarily reproduce asexually, occasional sex can have important evolutionary consequences. Many plant species in the genus Oenothera have a genetic system called permanent translocation heterozygosity (PTH), which renders plants functionally asexual when they self-fertilize. PTH results from reciprocal translocations of chromosomes that suppress recombination and a balanced lethal mortality of homozygous gametes that prevents independent assortment of alleles. When PTH plants self-fertilize, the offspring are genetically identical to the parents, but when they outcross they can create new genotypes. Here, we sought to determine the outcrossing rate of natural populations of PTH Oenothera biennis L. (Onagraceae). We genotyped 46 parents from 14 populations in Tompkins County, NY, USA, and 754 of their offspring at highly polymorphic microsatellite loci. 99.5% of offspring were genetically identical to their seed parents, whereas 4 offspring out of 754 exhibited allelic mismatches with their seed parent. The estimated outcrossing rate ranged from 0.1% to 0.4%. Our study design also permitted us to estimate mutation rate of microsatellite loci, which ranged from 1.33 × 10−3 to 3.98 × 10−3. These results show that O. biennis typically exhibits a functionally asexual genetic system, but rare outcrossing events can generate novel genotypes that may have important evolutionary consequences. [ABSTRACT FROM AUTHOR]

Simple sequence repeat (SSR) markers are valuable genetic and genomic research tools and are extensively used in major crops. However, a paucity of available molecular markers in lentils (Lens culinaris Medik.) has significantly hindered genomic studies in this vital legume crop. In this study, we developed 33 new SSR markers for lentils using an enriched genomic library and tested their polymorphism in 10 lentil cultivars. We found that 16 (48.5%) SSR markers were polymorphic. The expected heterozygosity values of the polymorphic SSR markers ranged from 0.095 to 0.820, while observed heterozygosity values varied between 0.100 and 1.00. In addition, we tested the transferability of 86 SSR markers, including the 33 newly developed ones, to other legume species. Transferability rates of lentil SSR markers to other species varied between 13.76% (Vicia sativa L.) and 2.58% (Phaseolus vulgaris L. and Trifolium pratense L.). These new SSR markers could be used in further molecular breeding, population genetics, and genetic mapping studies in lentils and other legume species. [ABSTRACT FROM AUTHOR]

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases threatening wheat production both in Turkey and worldwide. However, the underlying genetic dynamics of Pst populations are not fully known in Turkey. To determine the population genetic structure and migration network among regional Pst populations, a total of 140 Pst isolates collected from six geographical regions of Turkey from 2018 to 2020 were sampled and genotyped using 21 simple sequence repeat loci. A total of 70 multilocus genotypes were identified and classified into the three major genetic groups by Bayesian assignment. The highest genotypic diversity was detected in Southeastern Anatolia, showing its critical role as one of the source populations to trigger possible stripe rust epidemics. Analysis of molecular variance revealed the highest variation (90.25%) within isolates. The migration network generated by the number of effective migrants showed that the highest migration (1.0) was determined between Southeastern Anatolia and Central Anatolia, and considerable levels of migration (>0.2) were determined among the other regions, except for the Black Sea. Linkage equilibrium (P > 0.05) was detected for many geographical regions, except for Marmara (P = 0.00) and the Mediterranean (P = 0.03), suggesting that reproduction of Pst populations is most likely sexual or mixed (sexual and clonal). To sum up, this is the first study on the genetic relationships and population genetic structure of the Pst population in Turkey, and these findings may provide critical information to develop management strategies for wheat stripe rust. [ABSTRACT FROM AUTHOR]

Abstract Dicliptera tinctoria is a member of Acanthaceae, which has a wide distribution and contains potentially medicinal species, and exhibited pharmaceutical potentials. This study sequenced and characterized the complete chloroplast genome of Dicliptera tinctoria. The newly sequenced cpDNA of D. tinctoria was 150,733 bp in length and had a typical quadripartite structure consisting of a large single copy (LSC, 82,895 bp), a small single copy (SSC, 17,249 bp), and two inverted repeat (IRs, 25,295 bp each) regions. This genome also contained 80 protein-coding genes, 30 transfer RNAs, and four ribosomal RNAs, which is identical to other chloroplast genomes in Acanthaceae family. Nucleotides diversity analysis among chloroplast genomes of Acanthaceae species revealed eight hypervariable regions, including trnK_UUU-matK, trnC_GCA-petN, accD, rps12-clpP, rps3-rps19, ycf1-ndhF, ccsA-ndhD, and ycf1. Phylogenetic analysis revealed the paraphyly of Dicliptera species and monophyly in four Acanthaceae subfamilies. These results provide an overview of genomic variations in Acanthaceae chloroplast genome, which is helpful for further genomic studies.

IntroductionThe Cucurbitaceae family comprises many agronomically important members, that bear nutritious fruits and vegetables of great economic importance. Coccinia grandis, commonly known as Ivy gourd, belongs to this family and is widely consumed as a vegetable. Members of this family are known to display an impressive range of variation in fruit morphology. Although there have been studies on flower development in Ivy gourd, fruit development remains unexplored in this crop.MethodsIn this study, comparative transcriptomics of two Ivy gourd cultivars namely “Arka Neelachal Kunkhi” (larger fruit size) and “Arka Neelachal Sabuja” (smaller fruit size) differing in their average fruit size was performed. A de novo transcriptome assembly for Ivy gourd was developed by collecting fruits at different stages of development (5, 10, 15, and 20 days after anthesis i.e. DAA) from these two varieties. The transcriptome was analyzed to identify differentially expressed genes, transcription factors, and molecular markers.ResultsThe transcriptome of Ivy gourd consisted of 155205 unigenes having an average contig size of 1472bp. Unigenes were annotated on publicly available databases to categorize them into different biological functions. Out of these, 7635 unigenes were classified into 38 transcription factor (TF) families, of which Trihelix TFs were most abundant. A total of 11,165 unigenes were found to be differentially expressed in both the varieties and the in silico expression results were validated through real-time PCR. Also, 98768 simple sequence repeats (SSRs) were identified in the transcriptome of Ivy gourd.DiscussionThis study has identified a number of genes, including transcription factors, that could play a crucial role in the determination of fruit shape and size in Ivy gourd. The presence of polymorphic SSRs indicated a possibility for marker-assisted selection for crop breeding in Ivy gourd. The information obtained can help select candidate genes that may be implicated in regulating fruit development and size in other fruit crops.

AbstractThe family Orchidaceae is renowned for its extensive diversity. Within this family, the genus Goodyera R. Br. is classified under the subtribe Goodyerinae, comprising approximately 99 species. In this study, a species Goodyera yunnanensis Schltr., its plastid genome was characterized. The plastid genome of G. yunnanensis is 146,197 bp in size and exhibits a typical quadripartite structure with a pair of inverted repeat regions (IRs) of 25,611 bp, a large single-copy region (LSC) of 81,300 bp and a small single-copy region (SSC) of 13,675 bp. A total of 126 genes were identified, containing 80 protein-coding genes, 38 tRNA genes and 8 rRNA genes. The overall GC content is 37.2%, with corresponding values of 43.3%, 34.7% and 29.1% in IR, LSC and SSC regions, respectively. Forty-seven simple sequence repeats (SSRs) are found in G. yunnanensis plastome, and the frequency of mononucleotide repeats is significantly higher than other repeat types. Phylogenetic analysis indicates that Goodyera is resolved into four clades. G. yunnanensis belongs to the monophyletic clade A, and its phylogenetic position can be reasonably supported by morphological and molecular data.

Simple sequence repeat (SSR) markers are valuable genetic and genomic research tools and are extensively used in major crops. However, a paucity of available molecular markers in lentils (Lens culinaris Medik.) has significantly hindered genomic studies in this vital legume crop. In this study, we developed 33 new SSR markers for lentils using an enriched genomic library and tested their polymorphism in 10 lentil cultivars. We found that 16 (48.5%) SSR markers were polymorphic. The expected heterozygosity values of the polymorphic SSR markers ranged from 0.095 to 0.820, while observed heterozygosity values varied between 0.100 and 1.00. In addition, we tested the transferability of 86 SSR markers, including the 33 newly developed ones, to other legume species. Transferability rates of lentil SSR markers to other species varied between 13.76% (Vicia sativa L.) and 2.58% (Phaseolus vulgaris L. and Trifolium pratense L.). These new SSR markers could be used in further molecular breeding, population genetics, and genetic mapping studies in lentils and other legume species.

Genetic breeding is an important approach to improve the economic traits of aquaculture animals. Unfortunately, the genetic basis for important economic traits of red swamp crayfish, including growth-related traits, has not yet been reported. In the present study, two full-sib families and two natural populations were employed to identify quantitative trait loci (QTLs) for growth-related traits of red swamp crayfish. In total, 28 QTLs for five growth-related traits, including body weight, body length, carapace length, carapace width, and abdomen length, were repeatedly identified in more than two families/populations, by means of association analysis; nine of these displayed a heterosis effect. The phenotypic variations of the five investigated traits explained by the 28 QTLs ranged from 4.2% to 19.0%. Eight additive and three heterosis QTLs were further successfully validated using comparative analysis of favoured alleles between the small and big size crayfish groups in the natural population. In conclusion, this study investigated the genetic basis of growth-related traits in red swamp crayfish, which is of great significance for their application in the future molecular breeding of the species.

Genetic markers are powerful tools for understanding genetic diversity and the molecular basis of traits, ushering in a new era of molecular breeding in crops. Over the past 50 years, DNA markers have rapidly changed, moving from hybridization-based and second-generation-based to sequence-based markers. Simple sequence repeats (SSRs) are the ideal markers in plant breeding, and they have numerous desirable properties, including their repeatability, codominance, multi-allelic nature, and locus specificity. They can be generated from any species, which requires prior sequence knowledge. SSRs may serve as evolutionary tuning knobs, allowing for rapid identification and adaptation to new circumstances. The evaluations published thus far have mostly ignored SSR polymorphism and gene evolution due to a lack of data regarding the precise placements of SSRs on chromosomes. However, NGS technologies have made it possible to produce high-throughput SSRs for any species using massive volumes of genomic sequence data that can be generated fast and at a minimal cost. Though SNP markers are gradually replacing the erstwhile DNA marker systems, SSRs remain the markers of choice in orphan crops due to the lack of genomic resources at the reference level and their adaptability to resource-limited labor. Several bioinformatic approaches and tools have evolved to handle genomic sequences to identify SSRs and generate primers for genotyping applications in plant breeding projects. This paper includes the currently available methodologies for producing SSR markers, genomic resource databases, and computational tools/pipelines for SSR data mining and primer generation. This review aims to provide a ‘one-stop shop’ of information to help each new user carefully select tools for identifying and utilizing SSRs in genetic research and breeding programs.

Next-generation sequencing technologies have opened new avenues for using genomic data to study and develop molecular markers and improve genetic resources. Simple Sequence Repeats (SSRs) as genetic markers are increasingly used in molecular diversity and molecular breeding programs that require bioinformatics pipelines to analyze the large amounts of data. Therefore, there is an ongoing need for online tools that provide computational resources with minimal effort and maximum efficiency, including automated development of SSR markers. These tools should be flexible, customizable, and able to handle the ever-increasing amount of genomic data. Here we introduce MegaSSR (https:// bioinformatics.um6p.ma/MegaSSR), a web server and a standalone pipeline that enables the design of SSR markers in any target genome. MegaSSR allows users to design targeted PCR-based primers for their selected SSR repeats and includes multiple tools that initiate computational pipelines for SSR mining, classification, comparisons, PCR primer design, in silico PCR validation, and statistical visualization. MegaSSR results can be accessed, searched, downloaded, and visualized with user-friendly web-based tools. These tools provide graphs and tables showing various aspects of SSR markers and corresponding PCR primers. MegaSSR will accelerate ongoing research in plant species and assist breeding programs in their efforts to improve current genomic resources. [ABSTRACT FROM AUTHOR]

The family Orchidaceae is renowned for its extensive diversity. Within this family, the genus Goodyera R. Br. is classified under the subtribe Goodyerinae, comprising approximately 99 species. In this study, a species Goodyera yunnanensis Schltr., its plastid genome was characterized. The plastid genome of G. yunnanensis is 146,197 bp in size and exhibits a typical quadripartite structure with a pair of inverted repeat regions (IRs) of 25,611 bp, a large single-copy region (LSC) of 81,300 bp and a small single-copy region (SSC) of 13,675 bp. A total of 126 genes were identified, containing 80 protein-coding genes, 38 tRNA genes and 8 rRNA genes. The overall GC content is 37.2%, with corresponding values of 43.3%, 34.7% and 29.1% in IR, LSC and SSC regions, respectively. Forty-seven simple sequence repeats (SSRs) are found in G. yunnanensis plastome, and the frequency of mononucleotide repeats is significantly higher than other repeat types. Phylogenetic analysis indicates that Goodyera is resolved into four clades. G. yunnanensis belongs to the monophyletic clade A, and its phylogenetic position can be reasonably supported by morphological and molecular data. [ABSTRACT FROM AUTHOR]

Background Microsatellites or simple sequence repeats (SSR) consist of 1-6 nucleotide motifs of DNA or RNA which are ubiquitously present in tandem repeated sequences across genome in viruses: prokaryotes and eukaryotes. They may be localized to both the coding and non-coding regions. SSRs play an important role in replication, gene regulation, transcription, and protein function. The Caliciviridae (CLV) family of viruses have ss-RNA, non-enveloped, icosahedral symmetry 27-35 nm in diameter in size. The size of the genome lies between 6.4 and 8.6 kb. Results The incidence, composition, diversity, complexity, and host range of different microsatellites in 62 representatives of the family of Caliciviridae were systematically analyzed. The full-length genome sequences were assessed from NCBI (https://www.ncbi.nlm.nih.gov), and microsatellites were extracted through MISA software. The average genome size is about 7538 bp ranging from 6273 (CLV61) to 8798 (CLV47) bp. The average GC content of the genomes was ~ 51%. There are a total of 1317 SSRs and 53 cSSRs in the studied genomes. CLV 41 and CLV 49 contain the highest and lowest value of SSRs with 32 and 10 respectively, while CLV16 had maximum cSSR incidence of 4. There were 29 species which do not contain any cSSR. The incidence of mono-, di-, and tri-nucleotide SSRs was 219, 884, and 206, respectively. The most prevalent mono-, di-, and tri-nucleotide repeat motifs were "C" (126 SSRs), AC/CA (240 SSRs), and TGA/ACT (23 SSRs), respectively. Most of the SSRs and cSSRs are biased toward the coding region with a minimum of ~ 90% incident SSRs in the genomes' coding region. Viruses with similar host are found close to each other on the phylogenetic tree suggesting virus host being one of the driving forces for their evolution. Conclusions The Caliciviridae genomes does not conform to any pattern of SSR signature in terms of incidence, composition, and localization. This unique property of SSR plays an important role in viral evolution. Clustering of similar host in the phylogenetic tree is the evidence of the uniqueness of SSR signature. [ABSTRACT FROM AUTHOR]

The Aegean region makes a prominent contribution to Turkish viticulture. The region, which includes important grape culture centers such as Manisa, Denizli, and İzmir, has extremely favorable conditions for the cultivation of seedless grapes as well as table and wine grape varieties. In this region, which possesses rich grapevine genetic diversity together with its area and production potential, it is seen that there is variety confusion caused by different nomenclature and intravariety variations. In addition, some old grape varieties that are not used in cultivation are at risk of disappearing. In order to address these problems, the viticulture potentials of Manisa, Muğla, İzmir, Kütahya, Aydın, Denizli, Uşak, and Afyon provinces as populations were evaluated using simple sequence repeat (SSR) markers. In and research conducted using 15 SSR markers on 151 grape varieties including 149 native and 2 reference varieties, 3 similar (identical), 7 synonymous, and 13 homonymous cases were determined. The highest numbers of alleles were seen at the VVMD7 (14 alleles) and VVS2 (13 alleles) loci. The highest genetic similarity ratio among the genotypes was found to be 0.96 (96%) and the lowest value was 0.13 (13%). In population structure analysis, it was observed that there was significant gene flow among the Aegean region populations, while in Bayesian analysis, it was determined that the Aegean region populations (except the Aydın and İzmir populations) were highly admixed. The findings obtained in this research, which was carried out for the characterization of grape genetic resources at the SSR level on a regional scale, shed light for other genetic characterization studies. In addition, the results of this research may contribute to other viticulture activities (breeding, reproduction, variety registration, etc.) to be carried out in the region. [ABSTRACT FROM AUTHOR]

Strawberry (Fragaria x ananassa Duchesne ex Rozier) is an economically important fruit crop grown commercially worldwide due to its known nutritional value. The demand for strawberries in the Philippines has been increasing but varietal development is slow due to the lack of genetic information on locally available germplasm. In addition, molecular marker resources for strawberries are limited. Here, we developed Simple Sequence Repeats (SSR) markers to characterize strawberries cultivated in tropical environments, particularly in the Philippines. In silico mining generated a total of 219,239 SSR markers, from which 160,025 unique markers were identified. Polymorphism scoring and the variation on the expected alleles resulting to the synthesis of the top 160 markers were validated using representative strawberry cultivars from the core collection. All 70 markers produced successful amplicons from all the genotypes, but only 67 markers displayed polymorphism. Using UPGMA, genetic similarities among the cultivars were calculated generating a dendrogram which categorized the strawberry cultivars into 3 groups. The grouping clearly showed the separation of the diploid Fragaria vesca from the octoploid F. x ananassa cultivars, considered as group 1. Furthermore, Groups 2 and 3 contained cultivars from different geographical origins (US, Japan, and North America). The eight novel markers developed and validated here can be added to the genetic marker resource for cultivar verification, assessment of genetic diversity, and most importantly, marker-assisted breeding. [ABSTRACT FROM AUTHOR]

Knowing the extent of genetic variability among and within barley accessions provide bases of selection for breeders. However, given the heterogeneous nature of the germplasm, genetic information about barley landraces stored in gene bank of Ethiopia is not well archived. Therefore, genetic diversity study was conducted among and within 20 barley accessions represented by 194 barley plants. The accessions originate from 10 different geographic regions of Ethiopia covering a wide range of altitudes. The accessions were tested using 15 simple sequence repeat markers (SSRs). The SSR markers detected 57 alleles ranging from two (GBM1042) to seven (Bmac0040) alleles per marker indicating the genetic diversity in the barley plants. The allelic diversity across geographic regions and altitude reveals that barley accessions collected from mid and low altitudes of Ethiopia show high allelic diversity compared to accessions originating from high altitudes. Analysis of molecular variance results based on geographic regions (64.39%) and altitude classes (64.04%) also showed the highest variation within accessions compared to among accessions and groups. Both geographic regions and altitude-based genetic structure analysis detected two sub-populations. The individual assignment following the altitude of collection revealed the role of altitude in shaping the genetic diversity observed in barley populations. In general, the result of this study shows that each single barley line within the accessions should be considered as a potential source of genetic material and must be treated distinctly during germplasm collection and utilization. [ABSTRACT FROM AUTHOR]

Columbia root-knot nematode, Meloidogyne chitwoodi, parasitizes potato plants and causes visible small brown dots in the tuber flesh that dramatically reduce the market value of the crop. In the Pacific Northwest, two races of M. chitwoodi, Race 1 and Race 2, and a pathotype, Race 1Roza, exist. The races and pathotype of M. chitwoodi are primarily differentiated based on host tests. Currently, M. chitwoodi can be differentiated from M. hapla and other Meloidogyne spp. based on morphology and molecular markers; however, the different pathotypes of M. chitwoodi cannot be differentiated using the aforementioned techniques. Based on the in silico genome comparison of M. chitwoodi Race 1, Race 2, and Race 1Roza, we developed diagnostic molecular markers that could successfully differentiate between M. chitwoodi races and the pathotype. We also developed three race-specific markers that can specifically amplify Race 1, Race 2, or Race 1Roza. Overall, we have potential markers that can successfully differentiate the two races and one pathotype of M. chitwoodi through simplex PCR, which has a potential application in plant disease diagnostics. [Figure: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Next-generation sequencing technologies have opened new avenues for using genomic data to study and develop molecular markers and improve genetic resources. Simple Sequence Repeats (SSRs) as genetic markers are increasingly used in molecular diversity and molecular breeding programs that require bioinformatics pipelines to analyze the large amounts of data. Therefore, there is an ongoing need for online tools that provide computational resources with minimal effort and maximum efficiency, including automated development of SSR markers. These tools should be flexible, customizable, and able to handle the ever-increasing amount of genomic data. Here we introduce MegaSSR (https://bioinformatics.um6p.ma/MegaSSR), a web server and a standalone pipeline that enables the design of SSR markers in any target genome. MegaSSR allows users to design targeted PCR-based primers for their selected SSR repeats and includes multiple tools that initiate computational pipelines for SSR mining, classification, comparisons, PCR primer design, in silico PCR validation, and statistical visualization. MegaSSR results can be accessed, searched, downloaded, and visualized with user-friendly web-based tools. These tools provide graphs and tables showing various aspects of SSR markers and corresponding PCR primers. MegaSSR will accelerate ongoing research in plant species and assist breeding programs in their efforts to improve current genomic resources.

Abstract The GenoSSRFinder is a new tool enables the research of Simple Sequence Repeats (SSRs) in DNA sequences and genomes much simpler and more precise in short time. The analysis is carried out by targeting a certain SSR in genome and gene sequences. This utility is quick, accurate, and does its function quite well. It quickly goes across the sequence, revealing all of the locations at which the selected SSR may be found. This tool will tell researchers where selected SSR begins and where it stops, how long it is, how often it repeats, and how long each repetition is. GenoSSRFinder gets the findings quickly, and they will be simple to comprehend. Therefore, when studying SSRs, researchers will have more time to use to thorough work as a result of this time savings. In addition, it provides a valuable information since it is highly precise. GenoSSRFinder is simple to use and produces high-quality findings. It is also accelerating SSRs gene research, which is a direct result of the new approach we use to analyse SSRs. Three case studies in this study demonstrated the usefulness of this program by immediately studying a particular SSR that was associated with genetic illness, biodiversity and criminal science in living organisms. This demonstration explains that GenoSSRFinder might be utilized in a wide variety of fields, such as the research of genetic illnesses, the biodiversity and genetic studies, or even in criminal investigations.

In this study, we evaluated the occurrence, relative abundance (RA), and density (RD) of simple sequence repeats (SSRs) in the complete genome and transcriptomic sequences of the plant pathogenic species of Pythium to acquire a better knowledge of their genome structure and evolution. Among the species, P. ultimum had the highest RA and RD of SSRs in the genomic sequences, whereas P. vexans had the highest RA and RD in the transcriptomic sequences. The genomic and transcriptomic sequences of P. aphanidermatum showed the lowest RA and RD of SSRs. Trinucleotide SSRs were the most prevalent class in both genomic and transcriptomic sequences, while dinucleotide SSRs were the least prevalent. The G + C content of the transcriptomic sequences was found to be positively correlated with the number (r = 0.601) and RA (r = 0.710) of SSRs. A motif conservation study revealed the highest number of unique motifs in P. vexans (9.9%). Overall, a low conservation of motifs was observed among the species (25.9%). A gene enrichment study revealed P. vexans and P. ultimum carry SSRs in their genes that are directly connected to virulence, whereas the remaining two species, P. aphanidermatum and P. arrhenomanes, harbour SSRs in genes involved in transcription, translation, and ATP binding. In an effort to enhance the genomic resources, a total of 11,002 primers from the transcribed regions were designed for the pathogenic Pythium species. Furthermore, the unique motifs identified in this work could be employed as molecular probes for species identification. [ABSTRACT FROM AUTHOR]