Search Results (2,743)

RNA virus populations exist as quasispecies-complex, dynamic clouds of closely related but genetically diverse variants generated by high mutation rates during replication. Assessing quasispecies structure and diversity is crucial for understanding viral evolution, adaptation, and response to antiviral treatments. However, comparing single quasispecies observations from individual biosamples, especially at different infection or treatment time points, presents statistical challenges. Traditional inferential tests are inapplicable due to the lack of replicate observations, and resampling-based approaches such as the bootstrap and jackknife are limited by biases and non-independence, particularly for diversity indices sensitive to rare haplotypes. In this study, we address these limitations by applying the delta method to derive analytical variances for a set of quasispecies structure indicators specifically designed to assess the quasispecies maturation state. We demonstrate the utility of this approach using high-depth next-generation sequencing data from hepatitis C virus (HCV) quasispecies evolving in vitro under various conditions, including free evolution and exposure to antiviral or mutagenic treatments. Our results reveal that with highly fit HCV quasispecies, sofosbuvir inhibits quasispecies genetic diversity, while mutagenic treatments accelerate maturation, compared to untreated controls. We emphasize the interpretation of results through absolute differences, log-fold changes, and standardized effect sizes, moving beyond mere statistical significance. This framework enables robust, quantitative comparisons of quasispecies diversity from single observations, providing valuable insights into viral adaptation and treatment response. The R code and session info with required libraries and versions is provided in the supplementary material. Full article

The population size of black poplar (Populus nigra L.), once an important part of floodplain forests in the Czech Republic, has greatly declined due to human activity. In this study, we applied microsatellite (SSR) markers to identify species and assess genetic diversity, with the aim of supporting conservation of this endangered species. A total of 378 poplar trees were analyzed following field surveys. Five diagnostic SSR markers with species-specific alleles for P. deltoides Bartr. ex Marsh. enabled the identification of 39 interspecific hybrids, which were distinguished from native P. nigra. Thirteen SSR loci were used to evaluate genetic diversity among confirmed P. nigra individuals. The results revealed high genetic variation, with 66% of pairwise genotype comparisons differing at all loci. After excluding 45 genetically similar individuals, 292 genetically verified and polymorphic P. nigra trees were selected as potential sources of reproductive material. Genetic differentiation (Fst) was highest between P. nigra and P. deltoides (0.27), and lowest between reference Populus ×euroamericana clones and detected hybrid poplars (0.05) from natural localities. Distinct genetic structures were identified among P. nigra, P. deltoides, and hybrid individuals. These findings provide essential data for the protection, reproduction, and planting of black poplar. Full article

Background: Collabieae is a medium-sized group within the orchid subfamily Epidendroideae that is distributed primarily across tropical Asia. Most Collabieae species are known for their considerable ornamental and medicinal merits. However, habitat destruction and overharvesting have led to severe decline in their wild populations. Chloroplast (cp) genomes are highly valued in evolutionary studies, due to comparative conservation and accumulation of genomic variations. Elucidating the structure of chloroplast genome is instrumental in conserving genetic diversity within the Collabieae. Methods: we explored the chloroplast genome characteristics of Collabieae. We incorporated three newly sequenced genomes from species (Acanthophippium sylhetense, Eriodes barbata, and Spathoglottis plicata), along with seven related species. Results: all analyzed cp genomes displayed a typical quadripartite circular structure. The total lengths ranged from 157,036 bp to 158,321 bp. Each genome contained 136 genes: 88 protein-coding genes, 38 tRNA genes, eight rRNA genes, and two pseudogenes. Across the ten Collabieae species, gene number, order, orientation, GC content, and codon usage bias were highly consistent, indicative of strong sequence conservation. However, notable structural divergence was observed at the plastome junctions, alongside variations in SSR and repetitive element frequencies. Moreover, six hypervariable regions were identified. Noncoding regions exhibited higher variability compared to protein-coding regions. Phylogenetic analysis indicated that E. barbata forms a distinct, small branch sister to the rest of the Collabieae members. Genera Acanthophippium and Spathoglottis were sister to the remaining groups within the tribe. Conclusions: this overall phylogenetic framework aligns well with previous findings. Our study provides valuable cp genomic resources and advances evolutionary research in Collabieae. Full article

In this study, 944 Subo Merino sheep, a high-quality fine wool breed, were selected as research subjects. The SNP typing of the FAT3 gene was performed using the Fluidigm BiomarkTM HD system, and 11 missense mutation sites were identified. The analysis of population polymorphism of single-nucleotide polymorphisms was conducted. It is noteworthy that a substantial strong linkage disequilibrium was identified between SNP 5 and SNP 6 (r² > 0.8). The association between SNPs of the FAT3 gene and wool traits showed that multiple SNPs were significantly correlated with several different wool traits (p < 0.05). Furthermore, the investigation delved into the impact of the FAT3 gene on wool fiber through the utilization of quantitative polymerase chain reaction (qPCR), which yielded findings that this gene was notably expressed in fine wool fiber (FW) (p < 0.001). To predict the subcellular localization and protein transmembrane structure of FAT3, we employed the PSORT II Prediction and TMHMM online software. It was determined that the protein contains a transmembrane domain. This study provides molecular markers for the improvement of the selection and breeding of ultrafine-wool sheep and offers experimental evidence for accelerating the genetic breeding of sheep. Full article

Background/Objectives: Despite the increasing emergence of resistance, insecticide-based tools remain the primary method for malaria vector control in Africa. To maintain the effectiveness of these interventions, continuous monitoring and identification of novel resistance mechanisms is essential. This study aimed to investigate potential new insecticide resistance genes in the Anopheles gambiae complex. Methods: We analyzed whole-genome sequencing data from the An. gambiae 1000 Genomes Project. A broad range of genomic analysis techniques and tools were used to identify and explore genetic variation in the candidate resistance genes. Results: High haplotype homozygosity values, indicative of positive selection, were detected in a 2L chromosomal region corresponding to an aldehyde oxidase gene cluster (AGAP006220, AGAP006221, AGAP006224, AGAP006225, AGAP006226). Single nucleotide polymorphisms (SNPs) have been identified in these genes with frequencies up to 100%, including 569, 691, 1433, 978, and 811 non-synonymous SNPs in AGAP006220, AGAP006221, AGAP006224, AGAP006225, and AGAP006226, respectively. Copy number variations (CNVs) such as deletions and amplifications were also identified at low frequencies (<12%). Population structure analyses revealed adaptive and geographic gene flow between An. gambiae and An. coluzzii. Conclusions: This study provides evidence that aldehyde oxidase genes may contribute to insecticide resistance in An. gambiae s.l. populations. These results highlight the importance of genomic surveillance for detecting novel resistance loci and guiding the development of improved vector control strategies under changing ecological and evolutionary conditions. Full article

Background: Chinese Red Steppe cattle (CRS) combine indigenous environmental resilience with moderate dairy performance, whereas Holstein cattle (HOL), despite their high milk yield, suffer reduced genetic diversity and compromised adaptation. A comparative analysis of their population genetic architecture and selection signatures can reveal valuable targets for CRS dairy improvement. Methods: We genotyped 61 CRS and 392 HOL individuals using the Illumina GGP Bovine 100K SNP array and performed stringent quality control. Population structure was assessed via principal component analysis, neighbor-joining trees, and sparse nonnegative matrix factorization. Historical effective population size (Ne) and divergence time were inferred with SMC++. Genome-wide selection scans combined Fixation Index (FST) and Cross-Population Composite Likelihood Ratio test (XP-CLR); overlapping high-confidence regions were annotated and subjected to GO and KEGG enrichment analyses. Results: CRS and HOL were clearly separated along PC1 (explaining 57.48% of variance), with CRS exhibiting high internal homogeneity and weak substructure, versus greater diversity and complex substructure in HOL. SMC++ indicated a split approximately 3500 years ago (700 generations) and a pronounced recent decline in Ne for both breeds. Joint selection mapping identified 767 candidate genes; notably, the ACSM1/2B/3/4 cluster on chromosome 25—key to butanoate metabolism—showed the strongest signal. Enrichment analyses highlighted roles for proteasome function, endoplasmic reticulum stress response, ion homeostasis, and RNA processing in regulating milk fat synthesis and protein secretion. Conclusion: This study delineates the genetic divergence and demographic history of CRS and HOL, and pinpoints core genes and pathways—particularly those governing butanoate metabolism and protein quality control—underlying dairy traits. These findings furnish molecular markers and theoretical guidance for precision breeding and sustainable utilization of Chinese Red Steppe cattle. Full article

This study aimed to identify candidate genes associated with chlorophyll content in rice via genome-wide association studies (GWAS) and to develop molecular markers for the selection of genetic resources and breeding lines exhibiting high chlorophyll content. Measurement of the Soil and Plant Analysis Development (SPAD) values, indicative of chlorophyll content and photosynthetic potential, were measured in 198 rice genetic resources across three years under consistent nitrogen conditions. Nitrogen fertilizer (as urea) was applied at a rate of 90 kg N ha⁻¹. After analyzing the multi-year SPAD data, genetic resources with the coefficient of variation (CV) value exceeding 20% were excluded, and the remaining 175 accessions were used for subsequent analyses. Population structure analysis using the principal component analysis (PCA) and phylogenetic methods confirmed clear genetic differentiation, supporting the reliability of the GWAS. A GWAS using 289,569 SNPs identified 17 significant loci, among which four quantitative trait loci (QTLs)—qSV3-1, qSV3-2, qSV6, and qSV7—explained over 20% of phenotypic variance. Analysis of their additive effects revealed distinct SPAD distributions among QTL combination groups, with accessions harboring all four QTLs exhibiting the highest values. Candidate gene analysis within ± 200 kb of lead SNPs identified Os03g079100 (OsUCL8), involved in photosynthesis, near qSV3-2. A derived cleaved amplified polymorphic sequence (dCAPS) marker was developed to differentiate alleles at this locus and validated via restriction digestion. These results provide key genetic insights into chlorophyll accumulation and offer molecular markers for breeding high-yielding rice cultivars with enhanced chlorophyll content. The results of this study are expected to contribute to the development of sustainable rice varieties by utilizing the developed markers and identified candidate genes to increase SPAD values, thereby enhancing nitrogen use efficiency, improving photosynthetic capacity, and ultimately increasing rice productivity. Full article

Citrus tristeza virus (CTV) is an important pathogen threatening the global citrus industry, but its evolution and transmission mechanism in wild citrus has not been clarified. Most of the existing studies are based on CTV-specific gene fragments, lacking genome-wide analysis. There is especially a lack of understanding of CTV transmission dynamics in wild citrus, which needs further investigation. In this study, wild citrus samples from three provinces of China were collected, virus genome data were obtained by high-throughput sequencing (HTS) technology and combined with public database data, and Bayesian phylogeographic inference was used to analyze virus composition characteristics in wild citrus, as well as the population genetic structure, temporal dynamic evolution, and spatial transmission mode of CTV. The results showed that Yunnan wild citrus samples contained the most abundant virus components, including CTV, Citrus Exocortis Viroid (CEVd), Citrus associated Ampelovirus 1 (CaAV-1), and Citrus Virus B (CiVB), while Jiangxi and Hunan samples only contained CTV and CEVd, with all samples showing mixed infection. Phylogenetic analysis showed that nine wild citrus CTV isolates were scattered in different evolutionary clades, and only 9.27% of genetic variation existed between the populations, while 90.72% of genetic variation existed within the populations, indicating little effect of geographic isolation on gene flow. The time to the most recent common ancestor (tMRCA) of CTV was estimated at 1360 CE, with subsequent divergence into two lineages, with population size stabilizing after a rapid increase in 1980–1990. Asia has been identified as the central source of CTV’s global spread, with key migration events including Asia to North America (1746), Asia to Oceania (1829), and Asia to South America (1965), coinciding with global maritime trade and the expansion of the citrus industry. Full article

Myriophyllum spicatum is a globally distributed aquatic plant capable of sexual and clonal reproduction. Despite its ecological importance and biochemical potential, studies on its genetic and clonal structure in freshwater systems throughout South Korea remain limited. We investigated the genetic and clonal diversity of M. spicatum using 30 newly developed microsatellite markers across 120 individuals from six freshwater systems in South Korea. Overall, 148 alleles were identified, with an average polymorphism information content value of 0.530. Clonal diversity differed among populations, with the genotypes to individuals (G/N) ratio ranging from 0.200 to 1.000. Bottlenecks and clonal dominance were observed in riverine populations. High genetic differentiation (mean F_ST = 0.556) indicated limited gene flow, and STRUCTURE analysis revealed six distinct genetic clusters. No significant correlation was found between genetic and geographic distance, suggesting possible seed dispersal by waterfowl, particularly between adjacent populations. Genetic structure was shaped by habitat type, disturbance intensity, and reproductive strategy. Stable reservoir habitats favored sexual reproduction and higher genetic diversity, whereas disturbed river systems showed clonal dominance and reduced variation. These findings provide essential genetic insights for conservation planning and sustainable management of aquatic plant resources. Full article

Background: Tissue culture might be a method supplementing traditional plant propagation in various fields, like agriculture, medicine, industry, and the active conservation of plant species. For the purpose of plant restoration, it is important that the obtained progenies are identical with the mother plants to ensure the true-to-typeness of the future population. Methods: In the present study, the stability of Aldrovanda vesiculosa regenerants obtained in vitro through phenotypic and genetic analysis was estimated. Clones of aldrovanda plants were cultivated in tissue culture in the 1/10 MS liquid medium under the same conditions for over a year, with five weeks of subculturing. Results: It was observed that two clones formed plants that displayed atypical growth structures, the shoots were shorter with many lateral shoots, and they had a lower fresh weight. They also formed fewer and smaller snap-traps, which, in the case of carnivorous plants, determines the capability of catching prey. The 35 in vitro regenerated plants and 5 specimens obtained from the natural habitat were subjected to genetic analyses with two molecular markers: start codon targeted (SCoT) polymorphism and sequence-related amplified polymorphism (SRAP). Despite the visible morphological variants, the genetic stability of all the regenerants with the individuals from natural stands was confirmed. All of them were monomorphic except three bands that were obtained for reference, where individuals were amplified with SCoT28 and me12-em13 SRAP primers. Conclusions: As shown in the presented research, it might be recommended to use different methods to evaluate the stability of in vitro cultivated plants. Full article

Background/Objectives: Y-chromosomal short tandem repeats (Y-STR) are genetic markers widely used in forensic and population genetics. However, despite their importance, many populations remain under-represented in published studies and genetic databases. One such population is the Cape Verdean, which, despite its unique history of admixture between European and sub-Saharan African populations, continues to be under-represented in global Y-STR reference databases. This study aims to characterize the Y-STR haplotype diversity and paternal lineage composition of the Cape Verdean population using a high-resolution STR panel. Methods: A total of 143 unrelated Cape Verdean men were analyzed using a set of 26 Y-STR loci, including rapidly mutating markers. Allele and haplotype frequencies were calculated, along with standard forensic parameters such as gene and haplotype diversity. Paternal lineages were inferred, and genetic relationships with other populations were evaluated using distance-based and graphical methods. Results: A total of 135 haplotypes were detected, with 88.8% being unique, yielding a haplotype diversity of 0.999. The most common haplogroups reflected both West African and European ancestry. Genetic distance analysis positioned the Cape Verdean population between African and European groups, supporting its intermediate and admixed genetic background. Conclusions: This study provides the first high-resolution Y-STR dataset for Cape Verdeans, contributing valuable reference data for forensic casework and population genetic studies. The results highlight the utility of extended Y-STR panels in admixed populations and underscore the need to enhance the representation of admixed populations in international forensic reference databases. Full article

Germplasm resources embody the genetic diversity of plants and form the foundation for breeding and the ongoing improvement of elite cultivars. The establishment of germplasm banks, along with their systematic evaluation, constitutes a critical step toward the conservation, sustainable use, and innovative utilization of these resources. Liriodendron, a rare and endangered tree genus with species distributed in both East Asia and North America, holds considerable ecological, ornamental, and economic significance. However, a standardized evaluation system for Liriodendron germplasm remains unavailable. In this study, 297 Liriodendron germplasm accessions were comprehensively evaluated using 34 phenotypic traits and whole-genome resequencing data. Substantial variation was observed in most phenotypic traits, with significant correlations identified among several characteristics. Cluster analysis based on phenotypic data grouped the accessions into three distinct clusters, each exhibiting unique distribution patterns. This classification was further supported by principal component analysis (PCA), which effectively captured the underlying variation among accessions. These phenotypic groupings demonstrated high consistency with subsequent population structure analysis based on SNP markers (K = 3). Notably, several key traits exhibited significant divergence (p < 0.05) among distinct genetic clusters, thereby validating the coordinated association between phenotypic variation and molecular markers. Genetic diversity and population structure were assessed using 4204 high-quality single-nucleotide polymorphism (SNP) markers obtained through stringent filtering. The results indicated that the Liriodendron sino-americanum displayed the highest genetic diversity, with an expected heterozygosity (He) of 0.18 and a polymorphic information content (PIC) of 0.14. In addition, both hierarchical clustering and PCA revealed clear population differentiation among the accessions. Association analysis between three phenotypic traits (DBH, annual height increment, and branch number) and SNPs identified 25 highly significant SNP loci (p < 0.01). Of particular interest, the branch number-associated locus SNP_17_69375264 (p = 1.03 × 10⁻⁵) demonstrated the strongest association, highlighting distinct genetic regulation patterns among different growth traits. A minimal set of 13 core SNP markers was subsequently used to construct unique DNA fingerprints for all 297 accessions. In conclusion, this study systematically characterized phenotypic traits in Liriodendron, identified high-quality and core SNPs, and established correlations between key phenotypic and molecular markers. These achievements enabled differential analysis and genetic diversity assessment of Liriodendron germplasm, along with the construction of DNA fingerprint profiles. The results provide crucial theoretical basis and technical support for germplasm conservation, accurate identification, and utilization of Liriodendron resources, while offering significant practical value for variety selection, reproduction and commercial applications of this species. Full article

Although genomic selection can accelerate livestock breeding, its application in many countries is hindered due to the limited size of reference populations. To address this issue, researchers have explored methods of combining multiple breeds to create reference populations, aiming to enhance the accuracy of genomic prediction. The main objective of this study was to evaluate the impact of the construction of mixed reference populations at different genetic distance levels on the accuracy of multi-breed genome prediction in multi-breed beef cattle populations using three evaluation methods: GBLUP, ssGBLUP, and wGBLUP. In order to study the effect of genetic correlation on multiple populations and to resolve the optimal mixing ratio, we considered six scenarios, including (1) population A as the main body, where the nearest 10% of individuals in populations B and C were added; (2) population A was the main body, where the 15% of individuals with the closest genetic distance in groups B and C were added; and (3) population A as the main body, where the 20% of individuals in populations B and C with the closest genetic distance were added. Our results suggest that the wGBLUP model can be enhanced when the mixing ratio is 15%, and the wGBLUP model shows higher accuracy in predicting populations with different LD decay patterns. Among them, whether combined with PopB or PopC, the wGBLUP model shows better prediction ability than the GBLUP and ssGBLUP models. However, when the mixing ratio is 10% or 20%, the accuracy of the three models is less than 15%, and the wGBLUP and ssGBLUP models show high and stable accuracy. Our results highlight the importance of considering the proportion of mixing between different populations when using genetic assessment models to predict accuracy, especially for endemic beef cattle breeds with different genetic structures and LD patterns and limited resources. However, this study also has some limitations. First, the determination of the optimal mixing ratio still needs further exploration, especially for populations with different genetic structures and LD patterns. Second, future studies can introduce more advanced models to further improve prediction accuracy. Full article

The endangered Bengal slow loris (Nycticebus bengalensis) relies heavily on captive/rescue populations for conservation. This study investigated the critical link between Major Histocompatibility Complex (MHC) class II DRB1 exon 2 (DRB1e2) genetic variation and gut microbiota in 46 captive individuals, aiming to improve ex situ management. Using standardized conditions across three enclosure types, we characterized DRB1e2 polymorphism via targeted sequencing and analyzed fecal microbiota using 16S rRNA gene amplicon sequencing. Results demonstrated that high DRB1e2 polymorphism significantly reduced microbial community evenness. Specific genotypes showed distinct microbial associations: G9 strongly correlated with beneficial short-chain fatty acid producers like Fructobacillus, and G2 positively correlated with Bifidobacterium spp., while G2, G3, and G4 correlated negatively with Buchnera (a nutrient-provisioning symbiont). Genotypes and polymorphism collectively explained 9.77% of microbiota variation, exceeding the weaker (5.15%), though significant, influence of enclosure type on β-diversity. These findings reveal that host DRB1e2 variation is a primary driver shaping gut microbiota structure and taxon abundance in captive slow lorises, providing evidence for MHC-mediated host–microbe co-adaptation. This offers a genetically informed framework for optimizing conservation strategies, such as tailoring diets or probiotics to specific genotypes, to enhance gut health and population viability. Full article

Sugar beet (Beta vulgaris L.) is a biennial herbaceous plant belonging to the genus Beta within the family Amaranthaceae. Its root tuber can be used as an effective source for sucrose production. In the pursuit of sustainable development and maximizing the economic value of crops, the full utilization of crop germplasm resources and efficient production is necessary. To better facilitate the collection and utilization of sugar beet germplasm resources, this study used 106 accessions of multigerm sugar beet germplasm provided by the Key Laboratory of Molecular Genetic Breeding for sugar beet as materials. We evaluated the core collections constructed under various strategies using relevant genetic parameters and ultimately established two core collection construction strategies based on morphological and molecular markers. The optimal strategy based on morphological data was “Euclidean distance + Multiple clustering deviation sampling + UPGMA + 25% sampling proportion”, while the optimal strategy based on molecular marker data was “Jaccard distance + Multiple clustering random sampling + UPGMA + 20% sampling proportion”. In addition, representativeness evaluation of the core collection was conducted based on parameters related to both morphology and molecular markers. Principal component analysis (PCA) was utilized for the final determination of the core collection. The results showed that for both the morphological parameters and molecular marker-related parameters, there were no significant differences between the constructed core collection and the original germplasm; the phenotypic distribution frequencies were basically similar. Principal component analysis indicated that the core collection possessed a population structure similar to that of the original germplasm. The constructed core collection had good representativeness. This study, for the first time, proposed a core collection construction approach suitable for sugar beet by integrating morphological and molecular marker methodologies. It aimed to provide a scientific basis for the utilization and development of sugar beet germplasm resources, genetic improvement, and the breeding of new cultivars. Full article