scholarly journals Linkage disequilibrium and population structure in a core collection of Brassica napus (L.)

2021 ◽  
Author(s):  
Mukhlesur Rahman ◽  
Ahasanul Hoque ◽  
Jayanta Roy
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Linkage Disequilibrium ◽  
Core Collection ◽  
Crop Improvement ◽  
Snp Markers ◽  
Hybrid Breeding ◽  
Brassica Napus L ◽  
A Genome ◽  
C Genome

AbstractEstimation of genetic diversity in rapeseed/canola is important for sustainable breeding program to provide an option for the development of new breeding lines. The objective of this study was to elucidate the patterns of genetic diversity within and among different structural groups, and measure the extent of linkage disequilibrium (LD) of 383 globally distributed rapeseed/canola germplasm using 8,502 single nucleotide polymorphism (SNP) markers. The germplasm accessions were divided into five subpopulations (P1 to P5) with obvious geographic and growth habit-related patterns. All subpopulations showed moderate genetic diversity (average H = 0.22 and I = 0.34). The pairwise Fst comparison revealed a great degree of divergence (Fst > 0.24) between most of the combinations. The rutabaga type showed highest divergence with spring and winter types. Higher divergence was also found between winter and spring types. Overall, mean linkage disequilibrium was 0.03 and it decayed to its half maximum within < 45 kb distance for whole genome. The LD decay was slower in C genome (< 93 kb), relative to the A genome (< 21 kb) which was confirmed by availability of larger haplotype blocks in C genome than A genome. To maximize genetic gain, hybridization between rutabaga and other types are potentially the best option. Hybridization between spring and winter, semi-winter type is also helpful to maximize the diversity in subsequent populations. Low genetic differentiation between both spring type subpopulations (P4 and P3) will accelerate favorable allele accumulation for specific traits in elite lines. The Neighbor-Joining tree and kinship matrix will assist to identify distantly related genotypes from subpopulations to utilize in hybridization. The low levels of LD and population structure make the core collection an important resource for association mapping efforts to identify genes useful in crop improvement as well as for selection of parents for hybrid breeding.

scholarly journals Evaluation of linkage disequilibrium, population structure, and genetic diversity in the U.S. peanut mini core collection

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Paul I. Otyama ◽  
Andrew Wilkey ◽  
Roshan Kulkarni ◽  
Teshale Assefa ◽  
Ye Chu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Linkage Disequilibrium ◽  
Core Collection ◽  
Mini Core Collection ◽  
The U.S

scholarly journals Population structure and genetic diversity analyses of common bean germplasm collections of East and Southern Africa using morphological traits and high-density SNP markers

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243238
Author(s):  
Wilson Nkhata ◽  
Hussein Shimelis ◽  
Rob Melis ◽  
Rowland Chirwa ◽  
Tenyson Mzengeza ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Common Bean ◽  
Southern Africa ◽  
Crop Improvement ◽  
Phenotypic Expression ◽  
Snp Markers ◽  
High Yield ◽  
Gene Pools

Knowledge of genetic diversity in plant germplasm and the relationship between genetic factors and phenotypic expression is vital for crop improvement. This study's objectives were to understand the extent of genetic diversity and population structure in 60 common bean genotypes from East and Southern Africa. The common bean genotypes exhibited significant (p<0.05) levels of variability for traits such as days to flowering (DTF), days to maturity (DTM), number of pods per plant (NPP), number of seeds per pod (NSP), and grain yield per hectare in kilograms (GYD). About 47.82 per cent of the variation among the genotypes was explained by seven principal components (PC) associated with the following agronomic traits: NPP, NFF (nodes to first flower), DTF, GH (growth habit) and GYD. The SNP markers revealed mean gene diversity and polymorphic information content values of 0.38 and 0.25, respectively, which suggested the presence of considerable genetic variation among the assessed genotypes. Analysis of molecular variance showed that 51% of the genetic variation were between the gene pools, while 49% of the variation were within the gene pools. The genotypes were delineated into two distinct groups through the population structure, cluster and phylogenetic analyses. Genetically divergent genotypes such as DRK57, MW3915, NUA59, and VTTT924/4-4 with high yield and agronomic potential were identified, which may be useful for common bean improvement.

scholarly journals Whole Genome Diversity, Population Structure, and Linkage Disequilibrium Analysis of Chickpea (Cicer arietinum L.) Genotypes Using Genome-Wide DArTseq-Based SNP Markers

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 676 ◽  
Author(s):  
Farahani ◽  
Maleki ◽  
Mehrabi ◽  
Kanouni ◽  
Scheben ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Linkage Disequilibrium ◽  
Large Scale ◽  
Principal Component ◽  
Snp Markers ◽  
Genome Diversity ◽  
High Genetic Diversity ◽  
Breeding Programs ◽  
Population Structure Analysis

Characterization of genetic diversity, population structure, and linkage disequilibrium is a prerequisite for proper management of breeding programs and conservation of genetic resources. In this study, 186 chickpea genotypes, including advanced “Kabuli” breeding lines and Iranian landrace “Desi” chickpea genotypes, were genotyped using DArTseq-Based single nucleotide polymorphism (SNP) markers. Out of 3339 SNPs, 1152 markers with known chromosomal position were selected for genome diversity analysis. The number of mapped SNP markers varied from 52 (LG8) to 378 (LG4), with an average of 144 SNPs per linkage group. The chromosome size that was covered by SNPs varied from 16,236.36 kbp (LG8) to 67,923.99 kbp (LG5), while LG4 showed a higher number of SNPs, with an average of 6.56 SNPs per Mbp. Polymorphism information content (PIC) value of SNP markers ranged from 0.05 to 0.50, with an average of 0.32, while the markers on LG4, LG6, and LG8 showed higher mean PIC value than average. Unweighted neighbor joining cluster analysis and Bayesian-based model population structure grouped chickpea genotypes into four distinct clusters. Principal component analysis (PCoA) and discriminant analysis of principal component (DAPC) results were consistent with that of the cluster and population structure analysis. Linkage disequilibrium (LD) was extensive and LD decay in chickpea germplasm was relatively low. A few markers showed r2 ≥ 0.8, while 2961 pairs of markers showed complete LD (r2 = 1), and a huge LD block was observed on LG4. High genetic diversity and low kinship value between pairs of genotypes suggest the presence of a high genetic diversity among the studied chickpea genotypes. This study also demonstrates the efficiency of DArTseq-based SNP genotyping for large-scale genome analysis in chickpea. The genotypic markers provided in this study are useful for various association mapping studies when combined with phenotypic data of different traits, such as seed yield, abiotic, and biotic stresses, and therefore can be efficiently used in breeding programs to improve chickpea.

scholarly journals Genetic Diversity, Linkage Disequilibrium and Population Structure of Bulgarian Bread Wheat Assessed by Genome-Wide Distributed SNP Markers: From Old Germplasm to Semi-Dwarf Cultivars

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1116
Author(s):  
Vladimir Aleksandrov ◽  
Tania Kartseva ◽  
Ahmad M. Alqudah ◽  
Konstantina Kocheva ◽  
Krasimira Tasheva ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Linkage Disequilibrium ◽  
Bread Wheat ◽  
Clustering Algorithm ◽  
Agronomic Traits ◽  
Gene Diversity ◽  
Geographic Region ◽  
Snp Markers ◽  
Genetic Diversity And Structure

Genetic diversity and population structure are key resources for breeding purposes and genetic studies of important agronomic traits in crops. In this study, we described SNP-based genetic diversity, linkage disequilibrium and population structure in a panel of 179 bread wheat advanced cultivars and old accessions from Bulgaria, using an optimized wheat 25K Infinium iSelect array. Out of 19,019 polymorphic SNPs, 17,968 had а known chromosome position on the A (41%), B (42%) and D (11%) genome, and 6% were not assigned to any chromosome. Homoeologous group 4, in particular chromosome 4D, was the least polymorphic. In the total population, the Nei’s gene diversity was within the range 0.1-0.5, and the polymorphism information content ranged from 0.1 to 0.4. Significant differences between the old and modern collections were revealed with respect to the linkage disequilibrium (LD): the average values for LD (r2), the percentage of the locus pairs in LD and the LD decay were 0.64, 16% and 3.3 for the old germplasm, and 0.43, 30% and 4.1 for the modern releases, respectively. Structure and k-means clustering algorithm divided the panel into three groups. The old accessions formed a distinct subpopulation. The cluster analysis further distinguished the modern releases according to the geographic region and genealogy. Gene exchange was evidenced mainly between the subpopulations of contemporary cultivars. The achieved understanding of the genetic diversity and structure of the Bulgarian wheat population and distinctiveness of the old germplasm could be of interest for breeders developing cultivars with improved characteristics. The obtained knowledge about SNP informativeness and the LD estimation are worthwhile for selecting markers and for considering the composition of a population in association mapping studies of traits of interest.

scholarly journals Whole Genome Diversity, Population Structure and Linkage Disequilibrium Analysis of Chickpea (Cicer arietinum L.) Genotypes Using Genome-Wide DArTseq-Based SNP Markers

2019 ◽  
Author(s):  
Somayeh Farahani ◽  
Mojdeh Maleki ◽  
Rahim Mehrabi ◽  
Homayoun Kanouni ◽  
Reza Talebi
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Linkage Disequilibrium ◽  
Large Scale ◽  
Principal Component ◽  
Snp Markers ◽  
Genome Diversity ◽  
High Genetic Diversity ◽  
Breeding Programs ◽  
Population Structure Analysis

Characterization of genetic diversity, population structure and linkage disequilibrium is prerequisite for proper management of breeding programs and conservation of genetic resources. In this study, 186 chickpea genotypes including advanced &ldquo;Kabuli&rdquo; breeding lines and Iranian landrace &ldquo;Desi&rdquo; chickpea genotypes were genotyped using DArTseq-Based SNP markers. Out of 3339 SNPs, 1152 markers with known chromosomal position were selected for genome diversity analysis. The number of mapped SNP markers varied from 52 (LG8) to 378 (LG4), with an average of 144 SNPs per linkage group. The chromosome size that covered by SNPs varied from 16236.36 kbp (LG8) to 67923.99 kbp (LG5), while LG4 showed higher number of SNPs, with an average of 6.56 SNPs per Mbp. Polymorphism information content (PIC) value of SNP markers ranged from 0.05 to 0.50, with an average of 0.32, while the markers on LG4, LG6 and LG8 showed higher mean PIC value than average. Un-weighted Neighbor Joining cluster analysis and Bayesian-based model population structure grouped chickpea genotypes into four distinct clusters. Principal component analysis (PCoA) and Discriminant Analysis of Principal Component (DAPC) results were consistent with that of the cluster and population structure analysis. Linkage disequilibrium (LD) was extensive and LD decay in chickpea germplasm was relatively low. A few markers showed r2&ge;0.8, while 2961 pairs of markers showed complete LD (r2=1) and a huge LD block was observed on LG4. High genetic diversity and low kinship value between pairs of genotypes suggesting the presence of a high genetic diversity among studied chickpea genotypes. This study also demonstrated the efficiency of DArTseq-based SNP genotyping for large scale genome analysis in chickpea. The genotypic markers provided in this study are useful for various association mapping studies when combined with phenotypic data of different traits such as seed yield, abiotic and biotic stresses and therefore can be efficiently used in breeding programs to improve chickpea.

scholarly journals Genome-Wide and Mla Locus-Specific Characterisation of Latvian Barley Varieties

2008 ◽  
Vol 62 (3) ◽  
pp. 103-109
Author(s):  
Agnese Kokina ◽  
Nils Rostoks
Keyword(s):  
Genetic Diversity ◽  
Linkage Disequilibrium ◽  
Crop Improvement ◽  
Nucleotide Polymorphisms ◽  
Phenotypic Data ◽  
Genome Wide ◽  
A Genome ◽  
Wide Scale ◽  
Barley Germplasm ◽  
Mla Locus

Genome-Wide and Mla Locus-Specific Characterisation of Latvian Barley Varieties Genetic diversity in locally adapted germplasm forms the basis for crop improvement through breeding. While single loci have been routinely used for studies of genetic diversity, the highthroughput genotyping platforms that have recently become available for large genome crop plants offer an unbiased view on genetic diversity on a genome-wide scale. We assessed genetic diversity in Latvian barley varieties and some progenitors using DArT markers and studied the extent of linkage disequilibrium in Latvian germplasm. Further, genetic diversity at three loci flanking the barley powdery mildew Mla locus conferring race-specific resistance was studied in Latvian barley germplasm. The Mla locus encompasses several closely related resistance gene homologues with a complex evolutionary history, which complicates the design of molecular markers for different Mla genes. We observed significant linkage disequilibrium between the single nucleotide polymorphisms (SNPs) at the three loci, 206i20_T7, ABC15612, and 538P8, flanking the Mla locus. SNP haplotypes were largely in agreement with known phenotypic data and, thus, may be potentially diagnostic for Mla resistance genes in hybrids.

scholarly journals Genetic diversity and population structure of advanced clones selected over forty years by a potato breeding program in the USA

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jeewan Pandey ◽  
Douglas C. Scheuring ◽  
Jeffrey W. Koym ◽  
Joseph Coombs ◽  
Richard G. Novy ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Skin Color ◽  
Potato Breeding ◽  
Crop Improvement ◽  
Snp Markers ◽  
Breeding Program ◽  
Potato Breeding Program ◽  
The Usa

AbstractKnowledge regarding genetic diversity and population structure of breeding materials is essential for crop improvement. The Texas A&M University Potato Breeding Program has a collection of advanced clones selected and maintained in-vitro over a 40-year period. Little is known about its genetic makeup and usefulness for the current breeding program. In this study, 214 potato clones were genotyped with the Infinium Illumina 22 K V3 Potato Array. After filtering, a total of 10,106 single nucleotide polymorphic (SNP) markers were used for analysis. Heterozygosity varied by SNP, with an overall average of 0.59. Three groups of tetraploid clones primarily based on potato market classes, were detected using STRUCTURE software and confirmed by discriminant analysis of principal components. The highest coefficient of differentiation observed between the groups was 0.14. Signatures of selection were uncovered in genes controlling potato flesh and skin color, length of plant cycle and tuberization, and carbohydrate metabolism. A core set of 43 clones was obtained using Core Hunter 3 to develop a sub-collection that retains similar genetic diversity as the whole population, minimize redundancies, and facilitates long-term conservation of genetic resources. The comprehensive molecular characterization of our breeding clone bank collection contributes to understanding the genetic diversity of existing potato resources. This analysis could be applied to other breeding programs and assist in the selection of parents, fingerprinting, protection, and management of the breeding collections.

scholarly journals Identification of a Diverse Core Set Panel of Rice From the East Coast Region of India Using SNP Markers

2021 ◽  
Vol 12 ◽  
Author(s):  
Debjani Roy Choudhury ◽  
Ramesh Kumar ◽  
Vimala Devi S ◽  
Kuldeep Singh ◽  
N. K. Singh ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Core Collection ◽  
Tamil Nadu ◽  
East Coast ◽  
Snp Markers ◽  
The Core ◽  
Core Set ◽  
Population Structure Analysis ◽  
The Mean

In India, rice (Oryza sativa L.) is cultivated under a variety of climatic conditions. Due to the fragility of the coastal ecosystem, rice farming in these areas has lagged behind. Salinity coupled with floods has added to this trend. Hence, to prevent genetic erosion, conserving and characterizing the coastal rice, is the need of the hour. This work accessed the genetic variation and population structure among 2,242 rice accessions originating from India’s east coast comprising Andhra Pradesh, Orissa, and Tamil Nadu, using 36 SNP markers, and have generated a core set (247 accessions) as well as a mini-core set (30 accessions) of rice germplasm. All the 36 SNP loci were biallelic and 72 alleles found with average two alleles per locus. The genetic relatedness of the total collection was inferred using the un-rooted neighbor-joining tree, which grouped all the genotypes (2,242) into three major clusters. Two groups were obtained with a core set and three groups obtained with a mini core set. The mean PIC value of total collection was 0.24, and those of the core collection and mini core collection were 0.27 and 0.32, respectively. The mean heterozygosity and gene diversity of the overall collection were 0.07 and 0.29, respectively, and the core set and mini core set revealed 0.12 and 0.34, 0.20 and 0.40 values, respectively, representing 99% of distinctiveness in the core and mini core sets. Population structure analysis showed maximum population at K = 4 for total collection and core collection. Accessions were distributed according to their population structure confirmed by PCoA and AMOVA analysis. The identified small and diverse core set panel will be useful in allele mining for biotic and abiotic traits and managing the genetic diversity of the coastal rice collection. Validation of the 36-plex SNP assay was done by comparing the genetic diversity parameters across two different rice core collections, i.e., east coast and northeast rice collection. The same set of SNP markers was found very effective in deciphering diversity at different genetic parameters in both the collections; hence, these marker sets can be utilized for core development and diversity analysis studies.

Sign in / Sign up

Export Citation Format

Share Document