Polymorphic Single Nucleotide Polymorphism Markers Research Articles

Identification of Quantitative Trait Loci Associated with Plant Adaptation Traits Using Nested Association Mapping Population.

This study evaluated 290 recombinant inbred lines (RILs) of the nested association mapping (NAM) population from the UK. The population derived from 24 families, where a common parent was "Paragon," one of the UK's spring wheat cultivar standards. All genotypes were tested in two regions of Kazakhstan at the Kazakh Research Institute of Agriculture and Plant Industry (KRIAPI, Almaty region, Southeast Kazakhstan, 2019-2022 years) and Alexandr Barayev Scientific-Production Center for Grain Farming (SPCGF, Shortandy, Akmola region, Northern Kazakhstan, 2019-2022 years). The studied traits consisted of plant adaptation-related traits, including heading date (HD, days), seed maturation date (SMD, days), plant height (PH, cm), and peduncle length (PL, cm). In addition, the yield per m2 was analyzed in both regions. Based on a field evaluation of the population in northern and southeastern Kazakhstan and using 10,448 polymorphic SNP (single-nucleotide polymorphism) markers, the genome-wide association study (GWAS) allowed for detecting 74 QTLs in four studied agronomic traits (HD, SMD, PH, and PL). The literature survey suggested that 16 of the 74 QTLs identified in our study had also been detected in previous QTL mapping studies and GWASs for all studied traits. The results will be used for further studies related to the adaptation and productivity of wheat in breeding projects for higher grain productivity.

Genome-wide association analysis of tan spot disease resistance in durum wheat accessions from Tunisia.

Background: Tunisia harbors a rich collection of unexploited durum wheat landraces (Triticum durum ssp. durum) that have been gradually replaced by elite cultivars since the 1970s. These landraces represent an important potential source for broadening the genetic background of elite durum wheat cultivars and for the introgression of novel genes for key traits, including disease resistance, into these cultivars. Methods: In this study, single nucleotide polymorphism (SNP) markers were used to investigate the genetic diversity and population structure of a core collection of 235 durum wheat accessions consisting mainly of landraces. The high phenotypic and genetic diversity of the fungal pathogen Pyrenophora tritici-repentis (cause of tan spot disease of wheat) in Tunisia allowed the assessment of the accessions for tan spot resistance at the adult plant stage under field conditions over three cropping seasons. A genome-wide association study (GWAS) was performed using a 90k SNP array. Results: Bayesian population structure analysis with 9191 polymorphic SNP markers classified the accessions into two groups, where groups 1 and 2 included 49.79% and 31.49% of the accessions, respectively, while the remaining 18.72% were admixtures. Principal coordinate analysis, the unweighted pair group method with arithmetic mean and the neighbor-joining method clustered the accessions into three to five groups. Analysis of molecular variance indicated that 76% of the genetic variation was among individuals and 23% was between individuals. Genome-wide association analyses identified 26 SNPs associated with tan spot resistance and explained between 8.1% to 20.2% of the phenotypic variation. The SNPs were located on chromosomes 1B (1 SNP), 2B (4 SNPs), 3A (2 SNPs), 3B (2 SNPs), 4A (2 SNPs), 4B (1 SNP), 5A (2 SNPs), 5B (4 SNPs), 6A (5 SNPs), 6B (2 SNPs), and 7B (1 SNP). Four markers, one on each of chromosomes 1B, and 5A, and two on 5B, coincided with previously reported SNPs for tan spot resistance, while the remaining SNPs were either novel markers or closely related to previously reported SNPs. Eight durum wheat accessions were identified as possible novel sources of tan spot resistance that could be introgressed into elite cultivars. Conclusion: The results highlighted the significance of chromosomes 2B, 5B, and 6A as genomic regions associated with tan spot resistance.

Identification and Molecular Mapping of the Gene YrFL in Wheat Cultivar Flanders with Durable Resistance to Stripe Rust.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most severe diseases of wheat (Triticum aestivum L.) worldwide. Identification and characterization of resistance genes is advantageous to cultivating wheat varieties with durable resistance, which is the most economic and effective strategy to control stripe rust. Flanders, a common wheat cultivar released in France in 1986, confers effective resistance to stripe rust both at the seedling and adult plant stages. To elucidate the genetic basis of resistance in Flanders, F1, F2, and F2:3 generations derived from the cross Mingxian169 × Flanders were evaluated with the most prevalent Chinese Pst race CYR33 at the seedling stage. Inheritance analysis showed that the stripe rust resistance of Flanders was controlled by a single dominant gene, temporarily designated as YrFL. Bulked segregant analysis (BSA) combined with a wheat 660K single-nucleotide polymorphism (SNP) array indicated that polymorphic SNP markers were mainly located in the 0 to 150 Mb on wheat chromosome 5A. One hundred and eleven kompetitive allele-specific PCR (KASP) and 39 simple sequence repeat (SSR) markers on chromosome 5A were used to locate the YrFL. Linkage analysis mapped YrFL with 19 KASP and three SSR markers on wheat chromosome 5AS, and the genetic distances of the closest flanking markers AX108925494 and Xbarc56 to YrFL were 0.6 and 2.0 cM, respectively. Chromosome location, resistance characterization, and molecular marker positions indicated that YrFL is likely a novel stripe rust resistance gene on wheat chromosome 5AS and could be pyramided with other resistance genes to improve resistance in wheat breeding programs.

Association Mapping of Quantitative Trait Loci for Agronomic Traits in a Winter Wheat Collection Grown in Kazakhstan

Central Asia is an important region for the growth of winter wheat, with a cultivation area of more than 15 million hectares (ha). However, the average yield is approximately 3 tons per ha, which is significantly lower than that in developed countries. Therefore, the development of new competitive high-yielding cultivars, including those based on the application of modern molecular genetics tools, is a key priority in winter wheat breeding projects. One of these tools is the result of the identification of new genes and quantitative trait loci (QTLs) for agronomic traits using diverse germplasm panels and genome-wide association studies (GWAS). In this work, a panel of winter wheat accessions was assembled using 115 accessions from Central Asia and 162 samples from other regions of the world. The GWAS, based on a two-year field evaluation of the collection in Kazakhstan’s southern and southeastern regions and 10,481 polymorphic SNP (single-nucleotide polymorphism) markers, allowed for the detection of 173 stable QTLs in nine studied agronomic traits. A survey of the published scientific literature suggests that 23 of these 173 stable QTLs have locations similar to those of previously reported QTLs, supporting the robustness of the research. In addition, 221 and 162 accessions surpassed local standards for grain yield at Kazakhstan’s southern and southeastern stations, respectively. Therefore, this study is an additional contribution to the identification of new QTLs for key agronomic traits and valuable genetic lines in winter wheat breeding projects.

Single nucleotide polymorphism analysis in Leptospermum scoparium (Myrtaceae) supports two highly differentiated endemic species in Aotearoa New Zealand and Australia

Leptospermum scoparium is the basis of a flourishing honey industry in Aotearoa New Zealand (NZ) and Australia. The genetic structure of L. scoparium across its range in NZ and Australia was previously assessed using pooled, whole genome sequencing; however, only one sampling site in Tasmania was included. Here, we used a single nucleotide polymorphism (SNP) array for genotyping samples of L. scoparium collected in natural stands around Tasmania and NZ, to determine the genetic relationship between L. scoparium individuals from the two regions. In total, 2069 high quality, polymorphic SNP markers were applied across the sample set of 504 individuals, revealing that Tasmanian L. scoparium are genetically distinct from NZ mānuka, confirming the observation from the pooled whole genome sequencing project. FST and discriminant analysis of principal components confirmed that the Tasmanian populations are well differentiated genetically from NZ populations, suggesting that they should be recognised as a separate, endemic Australian species. Within NZ, eight geographic groups are distinguished with genotypic variation exhibiting north to south landscape scale patterns with regional genetic clusters. We found support for isolation by distance, and this was reflected in the range of pairwise FST values estimated between NZ genetic clusters (0.056 to 0.356); however, each geographic genetic group exhibits geneflow and is only weakly differentiated from neighbouring clusters as evidenced by low population differentiation (low pairwise FST). These data provide little support for taxonomic revision and subdividing L. scoparium into segregate species within NZ.

Identification of quantitative trait loci of agronomic traits in bread wheat using a Pamyati Azieva×Paragon mapping population harvested in three regions of Kazakhstan.

Although genome-wide association studies (GWAS) are an increasingly informative tool in the mining of new quantitative trait loci (QTLs), a classical biparental mapping approach is still a powerful, widely used method to search the unique genetic factors associated with important agronomic traits in bread wheat. In this study, a newly constructed mapping population of Pamyati Azieva (Russian Federation)×Paragon (UK), consisting of 94 recombinant inbred lines (RILs), was tested in three different regions of Kazakhstan with the purpose of QTL identification for key agronomic traits. The RILs were tested in 11 environments of two northern breeding stations (Petropavlovsk, North Kazakhstan region, and Shortandy, Aqmola region) and one southeastern station (Almalybak, Almaty region). The following eight agronomic traits were studied: heading days, seed maturation days, plant height, spike length, number of productive spikes, number of kernels per spike, thousand kernel weight, and yield per square meter. The 94 RILs of the PAxP cross were genotyped using Illumina's iSelect 20K single nucleotide polymorphism (SNP) array and resulted in the identification of 4595 polymorphic SNP markers. The application of the QTL Cartographer statistical package allowed the identification of 53 stable QTLs for the studied traits. A survey of published studies related to common wheat QTL identification suggested that 28 of those 53 QTLs were presumably novel genetic factors. The SNP markers for the identified QTLs of the analyzed agronomic traits of common wheat can be efficiently applied in ongoing breeding activities in the wheat breeding community using a marker-assisted selection approach.

Genomic dissection reveals QTLs for grain biomass and correlated traits under drought stress in Ethiopian durum wheat (Triticum turgidum ssp.durum)

AbstractDrought stress seriously challenges wheat production and productivity. Grain biomass (GB) and related traits were assessed under drought stress and non‐stress for 285 and 185 durum wheat genotypes, respectively, in field and climate chamber experiments to identify quantitative trait loci (QTL). Significant correlations between traits estimated in field and climate chamber trials were observed (p < .001). Genotyping with the wheat 90 K iSelect single nucleotide polymorphism (SNP) array revealed 11,919 polymorphic SNP markers distributed across the durum wheat genome. The FarmCPU (Fixed and random model Circulating Probability Unification) method was used for genome‐wide association studies (GWAS). A total of 191 significant (−log10p ≥ 4) marker‐trait associations (MTAs) were detected at a linkage disequilibrium (LD,r2 ≥ .2) at 4.78 Mb and were clustered into 70 QTLs. A total of 69 (36%) of the MTAs passed a false discovery rate (FDR) of 5%. The numbers of QTLs detected were 21, 31, 9 and 9 under field drought stress (FDS), field non‐stress (FNS), climate chamber drought stress (CCDS) and climate chamber non‐stress (CCNS) conditions, respectively. About 43% and 57% of the QTLs were located on the A and B genomes, respectively. Some of the detected QTLs were in agreement with previously reported QTLs, while others are novel ones for the traits investigated. QTLs on 1A between 495694477and ‐501944537bp, on 3B between 416256124 and 430507900 bp, on 3B between 745357158 and 759608934 bp, on 4B between 593416763 and 605142497 bp and on 4B between 658785890 and 670511624 bp were selected for validation and may be used to increase grain yield under drought stress in marker‐assisted selection (MAS) schemes.Key messageGenome‐wide association studies (GWAS) enabled detecting novel quantitative trait loci (QTLs) and identifying single nucleotide polymorphism (SNP) markers associated with grain biomass and correlated traits for drought stress tolerance in durum wheat based on a combination of climate chamber and multiyear and multilocation field experiments.

Development and characterization of 177 SNP markers in the mud shrimp Upogebia major

The mud shrimp Upogebia major (Crustacea, Decapoda, Gebiidea) (De Haan, 1841) is an ecological keystone species widely distributed in waters. It has contributed significantly to the maintenance of coastal benthic biodiversity as an ecosystem engineer. However, there is still a lack of effective molecular markers to effectively protect and manage this species. In this study, we used the DNeasy Blood & Tissue kit to extract DNA and Illumina HiSeq 4000 sequencing technology to obtain the SNP marker resources. A total of 177 single nucleotide polymorphism (SNP) markers were developed and characterized in U. major. The minor allele frequency ranged from 0.0500 to 0.5000. The observed heterozygosity and expected heterozygosity ranged from 0.0333 to 0.9000 and from 0.0966 to 0.5085, respectively. The polymorphic information content ranged from 0.0905 to 0.3750. The inbreeding coefficient values varied from − 0.2902 to 0.5968. Seventeen loci showed significant deviations from the Hardy–Weinberg equilibrium (P < 0.05). These polymorphic SNP markers will be helpful for the analysis of population genetic structure and the conservation of U. major.

Quantitative Trait Loci Mapping and Development of KASP Marker Smut Screening Assay Using High-Density Genetic Map and Bulked Segregant RNA Sequencing in Sugarcane (Saccharum spp.).

Sugarcane is one of the most important industrial crops globally. It is the second largest source of bioethanol, and a major crop for biomass-derived electricity and sugar worldwide. Smut, caused by Sporisorium scitamineum, is a major sugarcane disease in many countries, and is managed by smut-resistant varieties. In China, smut remains the single largest constraint for sugarcane production, and consequently it impacts the value of sugarcane as an energy feedstock. Quantitative trait loci (QTLs) associated with smut resistance and linked diagnostic markers are valuable tools for smut resistance breeding. Here, we developed an F1 population (192 progeny) by crossing two sugarcane varieties with contrasting smut resistance and used for genome-wide single nucleotide polymorphism (SNP) discovery and mapping, using a high-throughput genotyping method called “specific locus amplified fragment sequencing (SLAF-seq) and bulked-segregant RNA sequencing (BSR-seq). SLAF-seq generated 148,500 polymorphic SNP markers. Using SNP and previously identified SSR markers, an integrated genetic map with an average 1.96 cM marker interval was produced. With this genetic map and smut resistance scores of the F1 individuals from four crop years, 21 major QTLs were mapped, with a phenotypic variance explanation (PVE) > 8.0%. Among them, 10 QTLs were stable (repeatable) with PVEs ranging from 8.0 to 81.7%. Further, four QTLs were detected based on BSR-seq analysis. aligning major QTLs with the genome of a sugarcane progenitor Saccharum spontaneum, six markers were found co-localized. Markers located in QTLs and functional annotation of BSR-seq-derived unigenes helped identify four disease resistance candidate genes located in major QTLs. 77 SNPs from major QTLs were then converted to Kompetitive Allele-Specific PCR (KASP) markers, of which five were highly significantly linked to smut resistance. The co-localized QTLs, candidate resistance genes, and KASP markers identified in this study provide practically useful tools for marker-assisted sugarcane smut resistance breeding.

Genomic regions and candidate genes linked with Phytophthora capsici root rot resistance in chile pepper (Capsicum annuum L.)

BackgroundPhytophthora root rot, caused by Phytophthora capsici, is a major disease affecting Capsicum production worldwide. A recombinant inbred line (RIL) population derived from the hybridization between ‘Criollo de Morellos-334’ (CM-334), a resistant landrace from Mexico, and ‘Early Jalapeno’, a susceptible cultivar was genotyped using genotyping-by-sequencing (GBS)-derived single nucleotide polymorphism (SNP) markers. A GBS-SNP based genetic linkage map for the RIL population was constructed. Quantitative trait loci (QTL) mapping dissected the genetic architecture of P. capsici resistance and candidate genes linked to resistance for this important disease were identified.ResultsDevelopment of a genetic linkage map using 1,973 GBS-derived polymorphic SNP markers identified 12 linkage groups corresponding to the 12 chromosomes of chile pepper, with a total length of 1,277.7 cM and a marker density of 1.5 SNP/cM. The maximum gaps between consecutive SNP markers ranged between 1.9 (LG7) and 13.5 cM (LG5). Collinearity between genetic and physical positions of markers reached a maximum of 0.92 for LG8. QTL mapping identified genomic regions associated with P. capsici resistance in chromosomes P5, P8, and P9 that explained between 19.7 and 30.4% of phenotypic variation for resistance. Additive interactions between QTL in chromosomes P5 and P8 were observed. The role of chromosome P5 as major genomic region containing P. capsici resistance QTL was established. Through candidate gene analysis, biological functions associated with response to pathogen infections, regulation of cyclin-dependent protein serine/threonine kinase activity, and epigenetic mechanisms such as DNA methylation were identified.ConclusionsResults support the genetic complexity of the P. capsici–Capsicum pathosystem and the possible role of epigenetics in conferring resistance to Phytophthora root rot. Significant genomic regions and candidate genes associated with disease response and gene regulatory activity were identified which allows for a deeper understanding of the genomic landscape of Phytophthora root rot resistance in chile pepper.

Mining Single Nucleotide Polymorphism (SNP) Markers for Accurate Genotype Identification and Diversity Analysis of Chinese Jujube (Ziziphus jujuba Mill.) Germplasm

Chinese jujube (Ziziphus jujuba Mill.) is an economically important fruit tree with outstanding adaptability to marginal lands and a broad range of climate conditions. There are over 800 cultivars, mostly landraces from China. However, a high rate of mislabeling in Chinese jujube germplasm restricts the sharing of information and materials among jujube researchers and hampers the use of jujube germplasm in breeding. In the present study, we developed a large panel of single nucleotide polymorphism (SNP) markers and validated 288 SNPs by genotyping 114 accessions of Chinese jujube germplasm. The validation resulted in the designation of a set of 192 polymorphic SNP markers that revealed a high rate of synonymous mislabeling in the jujube germplasm collection in Ningxia, China. A total of 17 groups of duplicates were detected, encompassing 49 of the 114 Chinese jujube cultivars. Model-based population stratification revealed two germplasm groups, and the core members of the two groups showed a significant genetic differentiation (Fst = 0.16). The results supported the hypothesis that the cultivated Chinese jujube had multiple origins and multiple regions of domestication. The Neighbor-Joining dendrogram further revealed that this collection is comprised of multiple sub-groups, each including 1-13 closely related cultivars. Parentage analysis of cultivars with known pedigree information proved the efficacy of using these SNP markers for parentage verification. A subset of 96 SNPs with high information index was selected for future downstream application including gene bank management, verification of pedigrees in breeding programs, quality control for propagation of planting materials and support of the traceability and authentication of jujube products.

Development of 30 SNP markers for the Daphnia magna based on restriction-site associated DNA sequencing (RAD-seq)

Daphnia magna belongs to the Cladocera and plays an important role in the water ecosystem. With the intensification of water pollution, the wild population of D. magna has declined rapidly in recent years, and insufficient molecular markers have limited effective research and conservation of this species. In this research, 30 novel single nucleotide polymorphism (SNP) markers were developed in a cultivar of D. magna and 12 wild D. magna using restriction site-associated DNA sequencing (RAD-seq). The minor allele frequency, observed heterozygosity, and expected heterozygosity ranged from 0.115 to 0.483, 0.073 to 0.800, and 0.077 to 0.520, respectively. The PIC ranged from 0.071 to 0.403. Six loci showed significant deviations from the Hardy-Weinberg equilibrium after Bonferroni correction (p < 0.05).These newly developed polymorphic SNP markers for D. magna are of great significance in terms of the genetic breeding of D. magna, identification of wild and artificially domesticated species and conservation genetics research.

English

Brown blotch disease caused by Colletotrichum capsici, is one of the most important disease affecting cowpea production in Burkna Faso. Every year the disease can cause yield losses as high as 42 to 100% on farmer&rsquo;s fileds. This study aimed to understand the inheritance of its resistance in cowpea and also identify quantitative trait loci (QTL) associated with the resistance. Seedlings of parents and F1, F2 and BC1F1 progenies from crosses involving four susceptible and four resistant parents were screened in greenhouse conditions for brown blotch disease reaction. The inheritance studies indicated that different genes action were involved in the resistance of brown blotch resistance disease. In KN-1 variety, two or several genes associated to brown blotch were suggested. In Donsin local, a partially dominant gene, Rcc1, would be associated with the resistance. In Moussa local, a single major dominant gene, Rcc2, was identified. A single major recessive gene, rcc2, was found to control resistance with brown blotch in the cowpea resistant variety IT93K-503/46-13. The research of gene or QTL associated with brown blotch in cowpea variety KN-1 has been investigated. Polymorphic single nucleotide polymorphisms (SNP) markers and QTL associated to brown blotch resistance were discovered from 63 F2 individuals from a cross involving the susceptible variety Tiligre and the resistant KN-1. More than 11800 polymorphic SNP markers covered 1019.3 cM of the whole genome of cowpea were identified. A single dominant QTL, nomed qBBDR2 and 102 individual SNP markers tightly associated with the resistance of C. capsici were identified on chromosome 2 (Phytozome) of the cowpea genome. Key word: Cowpea, Colletotrichum capsici, resistance, inheritance, single nucleotide polymorphisms (SNP) marker, QTL.

High‐density linkage map construction and QTL analysis of fiber quality and lint percentage in tetraploid cotton

AbstractImproving fiber quality and yield are major research objectives for cotton breeders in the United States. Identifying broadly existing and stable quantitative trait loci (QTLs) related to fiber quality is critical to properly utilizing genomic resources in cotton improvement programs. An F6 recombinant inbred line (RIL) population derived from the cross of NC05AZ21 × TX‐2324 was used to develop linkage maps and for QTL analysis of six fiber quality traits and lint percentage. The Illumina 63K single nucleotide polymorphism (SNP) array was used to genotype the RIL population. Analysis of variance of phenotypic trait data showed significant differences among lines and years for all traits tested. The heritability for tested traits ranged from 0.56 to 0.91. Genetic mapping was performed using 3,009 polymorphic SNP markers on the RILs. We constructed a genetic map with a total length of 4,983.73 cM and an average distance of 1.66 cM between markers. The linkage map corresponded well with the Upland cotton (Gossypium hirsutum L.) sequence‐based physical map. Thirty‐two QTLs with additive effects for lint percentage and fiber quality traits were identified on 15 chromosomes, explaining 7.9–22.2% of the phenotypic variance. The majority of these QTLs were mapped in the D subgenome, indicating that functional mutations in the D subgenome are responsible for the major fiber quality improvements in Upland cotton. Furthermore, five QTL clusters were located on four chromosomes (Chr.05, Chr.18, Chr.19, and Chr.26), which may explain the strong correlation between fiber quality traits measured. The QTLs identified in the current study could be targeted for marker‐assisted selection and map‐based cloning of fiber quality traits in Upland cotton.

Affected-embryo-based SNP haplotyping with NGS for the preimplantation genetic testing of Marfan syndrome

ABSTRACT Marfan syndrome (MFS), an autosomal dominant heritable disease of the connective tissue, is characterized by broad clinical manifestations in the musculoskeletal, cardiovascular, pulmonary, and ocular systems. In this study, a male patient with MFS caused by a heterozygous mutation NM_000138.5(FBN1):c.6037 + 2 T > C in the fibrillin 1 gene (FBN1) underwent preimplantation genetic testing (PGT) by using affected-embryo-based single nucleotide polymorphism (SNP) haplotyping. Multiple displacement amplification was used for whole genome amplification of biopsied trophectoderm cells after controlled ovarian stimulation. Sanger sequencing and next-generation sequencing (NGS) were used to detect the state of FBN1 mutation. A total of 14 blastocysts formed after intracytoplasmic sperm injection were biopsied. After NGS, 60 informative polymorphic SNP markers located upstream and downstream of the FBN1 gene and its pathogenic mutation site were linked to individual alleles. Sanger sequencing further confirmed that 8 blastocysts carried the mutation NM_000138.5(FBN1):c.6037 + 2 T > C, while 6 did not. Four of the non-carriers were euploid verified by copy number variation results. A female infant without MFS was born at 37 weeks gestation after a subsequent frozen embryo transfer. In conclusion, the successful case indicates that SNP haplotyping using sibling embryos as a reference is applicable to PGT in monogenetic diseases. Abbreviations MFS: Marfan syndrome; PGT: preimplantation genetic testing; FBN1: fibrillin 1 gene; NGS: next-generation sequencing; SNP: single nucleotide polymorphism.

Development and characterization of 31 SNP markers for the Crested ibis (Nipponia nippon)

Single nucleotide polymorphisms (SNPs), known as the third-generation molecular markers, are becoming popular in molecular ecology studies. The rapid development of next generation sequencing technologies allow identifying large numbers of SNP markers that can be used in conservation genetics. Based on the genome resequencing dataset of Crested ibis (Nipponia nippon), we developed 31 polymorphic SNP markers using the restriction-site associated DNA (RAD) sequencing. The minor allele frequency per locus varied from 0.176 to 0.485, while the observed and expected heterozygosity varied from 0.118 to 0.794 and from 0.295 to 0.507, respectively. Three loci showed significant departures from Hardy–Weinberg equilibrium. These SNP markers could be useful in future population genetic analysis of Crested ibis.

A single nucleotide polymorphism assay sheds light on the extent and distribution of genetic diversity, population structure and functional basis of key traits in cultivated north American cannabis

BackgroundThe taxonomic classification of Cannabis genus has been delineated through three main types: sativa (tall and less branched plant with long and narrow leaves), indica (short and highly branched plant with broader leaves) and ruderalis (heirloom type with short stature, less branching and small thick leaves). While still under discussion, particularly whether the genus is polytypic or monotypic, this broad classification reflects putative geographical origins of each group and putative chemotype and pharmacologic effect.MethodsHere we describe a thorough investigation of cannabis accessions using a set of 23 highly informative and polymorphic SNP (Single Nucleotide Polymorphism) markers associated with important traits such as cannabinoid and terpenoid expression as well as fibre and resin production. The assay offers insight into cannabis population structure, phylogenetic relationship, population genetics and correlation to secondary metabolite concentrations. We demonstrate the utility of the assay for rapid, repeatable and cost-efficient genotyping of commercial and industrial cannabis accessions for use in product traceability, breeding programs, regulatory compliance and consumer education.ResultsWe identified 5 clusters in the sample set, including industrial hemp (K5) and resin hemp, which likely underwent a bottleneck to stabilize cannabidiolic acid (CBDA) accumulation (K2, Type II & III). Tetrahydrocannabinolic acid (THCA) resin (Type I) makes up the other three clusters with terpinolene (K4 - colloquial “sativa” or “Narrow Leaflet Drug” (NLD), myrcene/pinene (K1) and myrcene/limonene/linalool (K3 - colloquial “indica”, “Broad Leaflet Drug” (BLD), which also putatively harbour an active version of the cannabichrometic acid Synthase gene (CBCAS).ConclusionThe final chemical compositions of cannabis products have key traits related to their genetic identities. Our analyses in the context of the NCBI Cannabis sativa Annotation Release 100 allows for hypothesis testing with regards to secondary metabolite production. Genetic markers related to secondary metabolite production will be important in many sectors of the cannabis marketplace. For example, markers related to THC production will be important for adaptable and compliant large-scale seed production under the new US Domestic Hemp Production Program.

Genetic diversity of coffee (Coffea spp.) in Mexico evaluated by using DArTseq and SNP markers

The Coffea genus includes about 124 species, of which Coffea arabica L. and Coffea canephora Pierre ex A. Froehner are the most commercially important, supplying 63 and 37% of the world coffee production, respectively. C. arabica L. is associated with better cup quality, but presents serious problems with pests and diseases, potentiated by climate change. The development of new varieties of C. arabica L. requires the inclusion of genetic diversity, looking for incorporating new genes to tolerate or resist the most important pests and diseases, maintaining or improving yield and cup quality of the new materials. The technology of diversity arrays based on sequencing (DArTseq™) allows the rapid identification of the single nucleotide polymorphism (SNP) for a genomic approach of genetic diversity. The objectives of the present study were: (1) to evaluate the diversity and genetic structure of a central coffee collection of the Mexican National Bank of Coffee Germplasm; (2) assess the reproducibility and error rates of the markers and their broad representation in the genome and (3) to propose a new collection with representative and divergent promising genotypes for stablishing a coffee breeding program in Mexico. 87 coffee accessions of three different species of the Coffea genus were sequenced and 16,995 SNP markers were derived from 34,000 unique sequences obtained by the DArTseq™ method. After removing the markers with more than 10% of missing data and the MAF < 5%, we end up with 1739 polymorphic SNP markers for the analysis. A dendrogram was generated which divided the accessions into five divergent groups where promising genotypes were identified. In conclusion, there is genetic diversity among the accessions of Coffea spp. for use in future breeding programs.

Grain protein content and thousand kernel weight QTLs identified in a durum × wild emmer wheat mapping population tested in five environments.

Genetic dissection of GPC and TKW in tetraploid durum × WEW RIL population, based on high-density SNP genetic map, revealed 12 GPC QTLs and 11 TKW QTLs, with favorable alleles for 11 and 5 QTLs, respectively, derived from WEW. Wild emmer wheat (Triticum turgidum ssp. dicoccoides, WEW) was shown to exhibit high grain protein content (GPC) and therefore possess a great potential for improvement of cultivated wheat nutritional value. Genetic dissection of thousand kernel weight (TKW) and grain protein content (GPC) was performed using a high-density genetic map constructed based on a recombinant inbred line (RIL) population derived from a cross between T. durum var. Svevo and WEW acc. Y12-3. Genotyping of 208 F6 RILs with a 15K wheat single nucleotide polymorphism (SNP) array yielded 4166 polymorphic SNP markers, of which 1510 were designated as skeleton markers. A total map length of 2169cM was obtained with an average distance of 1.5cM between SNPs. A total of 12 GPC QTLs and 11 TKW QTLs were foundunder five different environments. No significant correlations were found between GPC and TKW across all environments. Four major GPC QTLs with favorable alleles from WEW were found on chromosomes 4BS, 5AS, 6BS and 7BL. The 6BS GPC QTL coincided with the physical position of the NAC transcription factor TtNAM-B1, underlying the cloned QTL, Gpc-B1. Comparisons of the physical intervals of the GPC QTLs described here with the results previously reported in other durum × WEW RIL population led to the discovery of seven novel GPC QTLs. Therefore, our research emphasizes the importance of GPC QTL dissection in diverse WEW accessions as a source of novel alleles for improvement of GPC in cultivated wheat.

Association mapping for agronomic traits in six-rowed spring barley from the USA harvested in Kazakhstan.

In barley, six-rowed barley is advantageous over two-rowed barley for feed due to the larger number of seeds per spike and the higher seed protein content. The growth of six-rowed barley is potentially important for breeding in agriculturally oriented countries, such as Kazakhstan. Nevertheless, until recently, very little attention was given to six-rowed barley in breeding projects in Kazakhstan, one of the largest countries in the world. In this study, phenotyping and single nucleotide polymorphism (SNP) genotyping data were generated from 275 accessions originating from six different breeding organizations in the USA as well as 9 accessions from Kazakhstan in field trials at six breeding institutions. The USA six-rowed barley was tested in comparison to local accessions over three years (2009–2011) based on analyses of key agronomic traits. It was determined that the average yield in the USA accessions in comparison to local lines showed heavier yield in all six tested sites. Principal Coordinate Analysis based on 1618 polymorphic SNP markers separated Kazakh lines from six USA barley origin groups based on PC1 (77.9%), and Montana lines from the remaining five USA groups based on PC2 (15.1%). A genome-wide association study based on eighteen field trials allowed the identification of 47 stable marker-trait associations (MTA) for ten agronomic traits, including key yield related characters such as yield per square meter, thousand grain weight, number of kernels per spike, and productive tillers. The comparison of chromosomal positions of identified MTA with positions of known genes and quantitative trait loci suggests that 25 out of those 47 MTAs are presumably novel. The analysis of 42 SNPs associated with 47 MTAs in the Ensemble genome annotation system (http://ensemblgenomes.org) suggested that 40 SNPs were in genic positions of the genome, as their sequences successfully aligned with corresponding Gen ID.