Population genetic diversity and structure of the endangered species Tetracentron sinense Oliver (Tetracentraceae) with SNPs based on RAD sequencing

Tetracentron sinense Oliv. (T. sinense), as a tertiary living fossil, has experienced a significant decline in population numbers. Currently, genetic resources depletion and human activities have led to habitat fragmentation of relict and endangered plants, despite the abundant evidence of its medicinal, economic, and ecological value. Conservation strategies were clarified and evaluated based on the genetic structure characteristics and diversity patterns among 25 wild populations using Restriction site-associated DNA sequencing (RAD-seq) technology. Through SNP calling, filtering, genetic diversity analysis, discriminant analysis of principal components (DAPC), maximum-likelihood phylogenetic tree, and ADMIXTURE clustering, significant population structure and differentiation were identified. The results revealed a total of 2,169 single nucleotide polymorphisms (SNPs), indicating lower genetic variation but higher genetic differentiation (He: 0.10, I: 0.16, Fst: 0.33). Analysis of molecular variance (AMOVA) showed that genetic variation within populations accounted for 77% of the total variance. DAPC, maximum-likelihood phylogenetic tree, and ADMIXTURE clustering analysis grouped the 25 populations into five distinct clades influenced by isolation, restricted gene flow, and complex topography. To preserve the genetic integrity of T. sinense, it is recommended to establish conservation units corresponding to different geographic clades, with a focus on populations with low/high genetic diversity by implementing artificial reproduction and germplasm resource nurseries. Given the species' vulnerable conservation status, urgent implementation of the aforementioned conservation strategies is necessary to safeguard the remaining genetic resources.

Brachiaria grass (Urochloa spp.) is one of the key forage grasses utilized in sub‐Saharan Africa for improving livestock productivity, particularly in terms of milk production and feed sufficiency. Limited information on its genetic resources has hindered its breeding and conservation strategies. This study used a set of 199 accessions collected across the Democratic Republic of Congo, which were genotyped using the Diversity Arrays Technology Sequencing platform. A total of 5787 high‐quality single nucleotide polymorphisms (SNPs) were used to evaluate genetic diversity and population structure. Markers were moderately informative in differentiating the accessions with average polymorphic information content and gene diversity of 0.29 and 0.08, respectively. Structure analysis showed seven sub‐populations (K = 7) with admixture corresponding to the geographical sources of the accessions. Discriminant analysis of principal component (DAPC) and principal component analysis further classified the accessions into five and six clusters, respectively. Genetic clustering was consistent with the DAPC and showed five main clusters with variable membership coefficients. Most pairs of accessions (80.6%) had a Euclidean genetic distance above 0.25, suggesting that most of them were genetically diverse. Mantel tests revealed a positive correlation between geographic and genetic distance among populations (r = 0.315, p = 0.0001), demonstrating consistency with the isolation by distance model. Analysis of molecular variance revealed significant differences between sub‐populations, 74.41%, and a high fixation index (Fst = 0.77) and low number of migrants per generation (Nm = 0.08), indicating high genetic differentiation and a low gene exchange among the sub‐populations and suggesting the presence of different Brachiaria grass species in our collection. The results revealed significant genetic diversity in the Brachiaria grass collection, which could be explored in genetic improvement, marker‐assisted breeding, and to enhance conservation management of this germplasm in the future.

Decision letter: Data-driven, participatory characterization of farmer varieties discloses teff breeding potential under current and future climates

BackgroundThe consumption of oats has rapidly increased due to their exceptional nutritional value. However, concerns over genetic erosion have emerged as oat breeding programs rely on a highly limited genetic pool. This study aimed to expand the genetic diversity pool of oats by collecting wild oat (Avena fatua L.) populations in South Korea and assessing their genetic diversity and seed storage protein patterns.ResultsA total of 237 A. fatua individuals were collected in 2022 from eight regions in the southwestern coastal areas of South Korea. Genetic diversity and seed storage protein patterns were analyzed using genotyping-by-sequencing (GBS) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The GBS analysis identified 20,836 single-nucleotide polymorphisms (SNPs). An analysis of molecular variance (AMOVA) based on regional populations revealed that 40.9% of the genetic variation was attributed to differences among populations, while 59.1% was within populations, indicating high genetic differentiation within regional populations. Subsequent population structure analysis and discriminant analysis of principal components (DAPC) both stated the formation of two distinct genetic groups, with an AMOVA value of 70.9% between the groups, suggesting a high level of genetic variation. Pairwise FST analysis was conducted to compare the genetic differentiation between two populations, revealing that Jindo and Jangheung exhibited the highest level of genetic differentiation (FST = 0.795) among the geographic groups. Seed storage proteins were analyzed using SDS-PAGE, and the patterns were grouped using k-means clustering. A comparison between the groups based on protein patterns and those based on genetic variation revealed no significant correlation.ConclusionThis study provides data on the genetic diversity of A. fatua, a wild relative of cultivated oats, aimed at expanding the genetic pool of oats for future breeding programs. These findings are expected to be a foundational resource for oat breeding and genetic improvement efforts.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12870-025-07315-x.

Landraces are considered a valuable source of potential genetic diversity that could be used in the selection process in any plant breeding program. Here, we assembled a population of 600 bread wheat landraces collected from eight different countries, conserved at the ICARDA's genebank, and evaluated the genetic diversity and the population structure of the landraces using single nucleotide polymorphism (SNP) markers. A total of 11,830 high-quality SNPs distributed across the genomes A (40.5%), B (45.9%), and D (13.6%) were used for the final analysis. The population structure analysis was evaluated using the model-based method (STRUCTURE) and distance-based methods [discriminant analysis of principal components (DAPC) and principal component analysis (PCA)]. The STRUCTURE method grouped the landraces into two major clusters, with the landraces from Syria and Turkey forming two clusters with high proportions of admixture, whereas the DAPC and PCA analysis grouped the population into three subpopulations mostly according to the geographical information of the landraces, i.e., Syria, Iran, and Turkey with admixture. The analysis of molecular variance revealed that the majority of the variation was due to genetic differences within the populations as compared with between subpopulations, and it was the same for both the cluster-based and distance-based methods. Genetic distance analysis was also studied to estimate the differences between the landraces from different countries, and it was observed that the maximum genetic distance (0.389) was between the landraces from Spain and Palestine, whereas the minimum genetic distance (0.013) was observed between the landraces from Syria and Turkey. It was concluded from the study that the model-based methods (DAPC and PCA) could dissect the population structure more precisely when compared with the STRUCTURE method. The population structure and genetic diversity analysis of the bread wheat landraces presented here highlight the complex genetic architecture of the landraces native to the Fertile Crescent region. The results of this study provide useful information for the genetic improvement of hexaploid wheat and facilitate the use of landraces in wheat breeding programs.

Single nucleotide polymorphisms (SNPs) are the most abundant form of genetic variation in eukaryote genomes and may be useful for selection of genetically distant parents for crossing in breeding programs. In this study, genome-wide SNPs of tall fescue (Festuca arundinacea Schreb.) were genotyped by using double-digest restriction-site-associated DNA sequencing to determine the genetic variation and differentiation among and within forage, turf and hybrid populations. After filtering, 16 036 SNPs were used to investigate genetic diversity and for structure analysis. SNP markers clearly differentiated the populations from each other. However, the hybrid population had a higher genetic similarity with the turf population than with the forage population. The results were confirmed by genetic differentiation (fixation index, Fst) and gene flow (Nm) statistics, so that low Fst and high Nm were observed between turf and hybrid groups, indicating less genetic distance and a high similarity between them. Based on the results of the weighted pair group method with arithmetic mean clustering, discriminant analysis of principal components and analysis of molecular variance, greater genetic differentiations were found among diverse turf, forage and hybrid populations, especially between turf and forage ones. In conclusion, numerous informative SNPs, natural allelic diversity-led domestication patterns, basic genetic variation statistics (e.g. Fst and heterozygosity) and population structures have multidimensional applicability for tall fescue genomics-assisted breeding.

Migrant populations of Helicoverpa zea (Boddie) captured during 2002, 2005, 2016, and 2018 from Landisville and Rock Springs in Pennsylvania, USA were genotyped using 85 single nucleotide polymorphism (SNP) markers. Samples (n = 702) genotyped were divided into 16 putative populations based on collection time and site. Fixation indices (F-statistics), analysis of molecular variance, and discriminant analysis of principal components were used to examine within and among population genetic variation. The observed and expected heterozygosity in putative populations ranged from 0.317–0.418 and 0.320–0.359, respectively. Broad range of FST (0.0–0.2742) and FIS (0.0–0.2330) values indicated different genotype frequencies between and within the populations, respectively. High genetic diversity within and low genetic differentiation between populations was found in 2002 and 2005. Interestingly, high genetic differentiation between populations from two collection sites observed in 2018 populations was not evident in within-site comparisons of putative populations collected on different dates during the season. The shift of H. zea population genetic makeup in 2018 may be influenced by multiple biotic and abiotic factors including tropical storms. Continued assessment of these peripheral populations of H. zea will be needed to assess the impacts of genetic changes on pest control and resistance management tactics.

Lethrinus lentjan (Lacepède, 1802) is an important commercial species for marine fisheries in subtropical and tropical regions of the Indian and Indo-Pacific oceans. Although heavily exploited, their genetic diversity and population structuring along the Vietnam coastline are unclear. Here, we used a panel of single nucleotide polymorphisms (SNPs) generated from restriction site-associated DNA sequencing (RADseq). After removing 405 outlier loci, 1,506 putatively neutral SNPs from 62 individuals were used to assess the genetic population structure of L. lentjan. Observed/expected heterozygosity (Ho/He) within sites ranged from 0.170/0.202 (Southeast) to 0.188/0.213 (Central). Pairwise FST values, Structure and Discriminant Analysis of Principal Components (DAPC) analysis indicate the lack of spatial genetic structure, suggesting the presence of a single panmictic population. Larval dispersal by ocean currents may facilitated high gene flow of L. lentjan along the Vietnamese coastline, and Mekong River outflow may not act as the natural barrier.

An in-depth understanding of the extent and pattern of genetic diversity and population structure in crop populations is of paramount importance for any crop improvement program to efficiently promote the translation of genetic diversity into genetic gain. A reference collection of 150 common bean genotypes selected from the International Center for Tropical Agriculture’s global core collection was evaluated using single-nucleotide polymorphism (SNP) markers to quantify the amount of genetic diversity, linkage disequilibrium, and population structure. The cultivars and landraces of the collection were diverse and originated from 14 countries, and wild accessions were used as controls for each gene pool. The collection was genotyped using an SNP array, generating a total of 5398 locus calls distributed across the entire bean genome. The SNP data quality was checked, and two datasets were generated. The first dataset (Dataset_1) comprised a set of 5108 SNPs and 150 genotypes after filtering for 10% missing alleles and an MAF < 0.05. The second dataset (Dataset_2) comprised a set of 2300 SNPs that remained after removing any null-allele SNPs and LD pruning for a criterion of r2 < 0.2. Dataset_1 was used for a principal coordinate analysis (PCoA), phylogenetic relationship determination, an analysis of molecular variance (AMOVA), and a discriminant analysis of principal components. Dataset_2 was used for a population structure analysis using STRUCTURE software and is proposed for a genome-wide association study (GWAS). The population structure analysis split the reference collection into two subpopulations according to an Andean or Mesoamerican gene pool. The Mesoamerican populations displayed higher genetic differentiation and tended to split into more groups that were somewhat aligned with common bean races. Andean beans were characterized by a larger average LD but lower LD percentage, a small average genetic distance between members of the population, and a higher major allele frequency, which suggested narrower genetic diversity compared to the Mesoamerican gene pool. In conclusion, the results indicated the presence of high genetic diversity, which is useful for a GWAS. However, the presence of significant linkage disequilibrium requires that genetic distance be considered as a co-factor for any further genetic studies. Overall, the molecular variation observed in the genotypes shows that this reference collection is valuable as a genebank-derived diversity panel which is useful for marker trait association studies.

Ternstroemia sylvatica inhabits several temperate and tropical montane forests in eastern Mexico. Its current discontinuous distribution results from both natural and anthropogenic fragmentation. We assessed the genetic diversity and population differentiation of T. sylvatica across its distribution range using 18 microsatellite markers. We sampled 366 individuals from 16 populations, analyzing genetic diversity (He) and population structure via STRUCTURE and Discriminant Analysis of Principal Components (DAPC). Our results revealed high genetic differentiation (FST = 0.21), with most genetic variation occurring within populations (79.50%). STRUCTURE analysis identified two major genetic clusters: a northern group, comprising the populations with the lowest genetic diversity, and a southern group with higher genetic diversity (He = 0.59–0.73) geographically structured into ten subgroups. Additionally, the results suggest historical fragmentation, limited gene flow among populations and inbreeding, as a heterozygote deficit is prevalent across populations. The high genetic diversity in specific populations indicates potential hybridization with other sympatric Ternstroemia species.

BackgroundTicks are crucial vectors of a wide range of pathogens, posing significant threats to human and animal health globally. Understanding the genetic basis of tick biology and host–parasite interactions is essential for developing effective control programs. This study investigates the fine-scale genetic structure of Hyalomma marginatum Koch, 1844, the primary vector of Crimean-Congo hemorrhagic fever (CCHF) in Türkiye. Despite its significant public health importance, information regarding its population structure and genetic diversity is quite limited.MethodsWe used restriction site-associated DNA sequencing (RAD-Seq) to obtain genome-wide sequence data from 10 tick populations in Türkiye, collected from regions with low, moderate, and high incidence rates of CCHF. Based on these data, we determined population structure and diversity of populations using principal component analysis (PCA) and admixture analysis. Furthermore, we calculated pairwise FST and utilized discriminant analysis of principal components (DAPC) to understand genetic differentiation between populations.ResultsPCA and admixture analysis indicated minimal genetic structure between populations, but we detected notable genetic differentiation and high genetic diversity from regions with high CCHF rates. Furthermore, our DAPC identified 31 significant single-nucleotide polymorphisms (SNPs) associated with regions with high CCHF incidence, with 25 SNPs located near genes involved in critical biological functions such as nucleic acid binding, transmembrane transport, and proteolysis. These findings suggest that genetic variations in these regions may confer adaptive advantages in environments with high pathogen loads.ConclusionsThis study provides the first comprehensive analysis of H. marginatum genetic diversity in Türkiye, revealing significant differentiation in populations from CCHF-endemic regions. These results underscore the importance of considering fine-scale genetic diversity to fully understand the drivers of genetic variation in ticks and their implications for vectorial capacity.Graphical

Brazil is among the largest producers and consumers of common bean (Phaseolus vulgaris L.) and can be considered a secondary center of diversity for the species. The aim of this study was to estimate the genetic diversity, population structure, and relationships among 288 common bean accessions in an American Diversity Panel (ADP) genotyped with 4,042 high-quality single nucleotide polymorphisms (SNPs). The results showed inter-gene pool hybridization (hybrids) between the two main gene pools (i.e., Mesoamerican and Andean), based on principal component analysis (PCA), discriminant analysis of principal components (DAPC), and STRUCTURE analysis. The genetic diversity parameters showed that the Mesoamerican group has higher values of diversity and allelic richness in comparison with the Andean group. Considering the optimal clusters (K), clustering was performed according to the type of grain (i.e., market group), the institution of origin, the period of release, and agronomic traits. A new subset was selected and named the Mesoamerican Diversity Panel (MDP), with 205 Mesoamerican accessions. Analysis of molecular variance (AMOVA) showed low genetic variance between the two panels (i.e., ADP and MDP) with the highest percentage of the limited variance among accessions in each group. The ADP showed occurrence of high genetic differentiation between populations (i.e., Mesoamerican and Andean) and introgression between gene pools in hybrids based on a set of diagnostic SNPs. The MDP showed better linkage disequilibrium (LD) decay. The availability of genetic variation from inter-gene pool hybridizations presents a potential opportunity for breeders towards the development of superior common bean cultivars.

Lactarius hatsudake is an ecologically and economically significant wild edible mushroom in southern China. To elucidate its population genetic diversity, differentiation, and evolutionary history, we analyzed 172 fruiting bodies from eight geographic populations (AQ, BS, DZ, JS, NC, PT, SG, YX) across seven provinces in the western and eastern regions of southern China using five highly polymorphic simple sequence repeat (SSR) markers. Combined with STRUCTURE clustering, discriminant analysis of principal components (DAPC), unweighted pair group method with arithmetic mean (UPGMA), and analysis of molecular variance (AMOVA), the results revealed high polymorphism across the studied loci (mean PIC = 0.842). A total of 75 alleles were identified, averaging 15 alleles per locus. At the population level, the mean effective number of alleles (Ne) was 4.023, and the mean unbiased gene diversity (uH) was 0.768. The NC population exhibited the highest genetic diversity (uH = 0.796), whereas the BS population showed relatively lower diversity (uH = 0.647). Clustering analyses (STRUCTURE, DAPC, and UPGMA) consistently identified two distinct genetic clusters (K = 2). Cluster I consisted of populations AQ, PT, BS, and SG, while Cluster II was composed of the remaining four populations. Notably, individuals from AQ and NC displayed significant genetic admixture, suggesting a transitional zone. AMOVA revealed that the majority of genetic variation (83%) resided within populations and 17% among populations. Moderate population differentiation (ENA-corrected global Fst = 0.102) and admixture signals suggest non-negligible connectivity among populations.

Ternstroemia sylvatica inhabits several temperate and tropical montane forests in eastern Mexico. Its current discontinuous distribution results from both natural and anthropogenic fragmentation. We assessed the genetic diversity and population differentiation of T. sylvatica across its distribution range using 18 microsatellite markers. We sampled 366 individuals from 16 populations, analyzing genetic diversity (He) and population structure via STRUCTURE and Discriminant Analysis of Principal Components (DAPC). Our results revealed high genetic differentiation (FST = 0.21), with most genetic variation occurring within populations (79.50%). STRUCTURE analysis identified two major genetic clusters: a northern group, comprising the populations with the lowest genetic diversity, and a southern group with higher genetic diversity (He = 0.59-0.73) geographically structured into ten subgroups. Additionally, the results suggest historical fragmentation, limited gene flow among populations and inbreeding, as a heterozygote deficit is prevalent across populations. The high genetic diversity in specific populations indicates potential hybridization with other sympatric Ternstroemia species.

Genetic diversity and population structure are fundamental to studying population dynamics and understanding demographic history, playing a key role in marine organism conservation. To study the genetic diversity and population structure of whitespotted conger Conger myriaster, an important commercial marine species, broadly distributed in Asia, a total of 197 individuals were collected from six locations along the East China Coast. Around 655 bp sequence of mitochondrial control region was used to assess the genetic diversity, population differentiation, and demographic history of C. myriaster populations. A high level of haplotype diversity was detected. No significant population structure was observed by using analysis of molecular variance (AMOVA), consistent with the results of discriminant analysis of principal components (DAPC) and Mantel tests. Bayesian phylogenetic tree revealed three distinct lineages, which diverged during the Pleistocene. Mismatch and Bayesian skyline analyses supported that all geographical populations as well as three evolutionary lineages had experienced demographic expansions. This genetic assessment would give an important contribution to revealing the interaction between phylogeographic history and demographic history and future utilization and conservation of this species.