scholarly journals A New Catalog of Structural Variants in 1,301 A. thaliana Lines from Africa, Eurasia, and North America Reveals a Signature of Balancing Selection at Defense Response Genes

2020 ◽  
Author(s):  
Mehmet Göktay ◽  
Andrea Fulgione ◽  
Angela M Hancock
Keyword(s):  
North America ◽  
Defense Response ◽  
Balancing Selection ◽  
Natural Populations ◽  
Housekeeping Genes ◽  
Intermediate Frequency ◽  
Genomic Variation ◽  
Nucleotide Polymorphisms ◽  
Structural Variants ◽  
Defense Response Genes

Abstract Genomic variation in the model plant Arabidopsis thaliana has been extensively used to understand evolutionary processes in natural populations, mainly focusing on single-nucleotide polymorphisms. Conversely, structural variation has been largely ignored in spite of its potential to dramatically affect phenotype. Here, we identify 155,440 indels and structural variants ranging in size from 1 bp to 10 kb, including presence/absence variants (PAVs), inversions, and tandem duplications in 1,301 A. thaliana natural accessions from Morocco, Madeira, Europe, Asia, and North America. We show evidence for strong purifying selection on PAVs in genes, in particular for housekeeping genes and homeobox genes, and we find that PAVs are concentrated in defense-related genes (R-genes, secondary metabolites) and F-box genes. This implies the presence of a “core” genome underlying basic cellular processes and a “flexible” genome that includes genes that may be important in spatially or temporally varying selection. Further, we find an excess of intermediate frequency PAVs in defense response genes in nearly all populations studied, consistent with a history of balancing selection on this class of genes. Finally, we find that PAVs in genes involved in the cold requirement for flowering (vernalization) and drought response are strongly associated with temperature at the sites of origin.

Beyond HLA: the significance of genomic variation for allogeneic hematopoietic stem cell transplantation

Blood ◽  
2006 ◽  
Vol 109 (4) ◽  
pp. 1355-1362 ◽  
Author(s):  
Ann Mullally ◽  
Jerome Ritz
Keyword(s):  
Stem Cell ◽  
Hematopoietic Stem Cell Transplantation ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Hematopoietic Stem Cell ◽  
Copy Number Variants ◽  
Genomic Variation ◽  
Nucleotide Polymorphisms ◽  
Structural Variants ◽  
Hematopoietic Stem

Abstract The last 2 years have seen much excitement in the field of genetics with the identification of a formerly unappreciated level of “structural variation” within the normal human genome. Genetic structural variants include deletions, duplications, and inversions in addition to the recently discovered, copy number variants. Single nucleotide polymorphisms are the most extensively evaluated variant within the genome to date. Combining our knowledge from these studies with our rapidly accumulating understanding of structural variants, it is apparent that the extent of genetic dissimilarity between any 2 individuals is considerable and much greater than that which was previously recognized. Clearly, this more diverse view of the genome has significant implications for allogeneic hematopoietic stem cell transplantation, not least in the generation of transplant antigens but also in terms of individual susceptibility to transplant-related toxicities. With advances in DNA sequencing technology we now have the capacity to perform genome-wide analysis in a high throughput fashion, permitting a detailed genetic analysis of patient and donor prior to transplantation. Understanding the significance of this additional genetic information and applying it in a clinically meaningful way will be one of the challenges faced by transplant clinicians in the future.

scholarly journals Intercontinental karyotype–environment parallelism supports a role for a chromosomal inversion in local adaptation in a seaweed fly

2018 ◽  
Vol 285 (1881) ◽  
pp. 20180519 ◽  
Author(s):  
Claire Mérot ◽  
Emma L. Berdan ◽  
Charles Babin ◽  
Eric Normandeau ◽  
Maren Wellenreuther ◽  
...  
Keyword(s):  
North America ◽  
Local Adaptation ◽  
Environmental Gradients ◽  
Balancing Selection ◽  
Chromosomal Rearrangements ◽  
Natural Populations ◽  
Inversion Polymorphism ◽  
Life History Strategies ◽  
Heterogeneous Environments ◽  
Adult Size

Large chromosomal rearrangements are thought to facilitate adaptation to heterogeneous environments by limiting genomic recombination. Indeed, inversions have been implicated in adaptation along environmental clines and in ecotype specialization. Here, we combine classical ecological studies and population genetics to investigate an inversion polymorphism previously documented in Europe among natural populations of the seaweed fly Coelopa frigida along a latitudinal cline in North America. We test if the inversion is present in North America and polymorphic, assess which environmental conditions modulate the inversion karyotype frequencies, and document the relationship between inversion karyotype and adult size. We sampled nearly 2000 flies from 20 populations along several environmental gradients to quantify associations of inversion frequencies to heterogeneous environmental variables. Genotyping and phenotyping showed a widespread and conserved inversion polymorphism between Europe and America. Variation in inversion frequency was significantly associated with environmental factors, with parallel patterns between continents, indicating that the inversion may play a role in local adaptation. The three karyotypes of the inversion are differently favoured across micro-habitats and represent life-history strategies likely to be maintained by the collective action of several mechanisms of balancing selection. Our study adds to the mounting evidence that inversions are facilitators of adaptation and enhance within-species diversity.

scholarly journals Pervasive Linked Selection and Intermediate-Frequency Alleles Are Implicated in an Evolve-and-Resequencing Experiment of Drosophila simulans

Genetics ◽  
2018 ◽  
Vol 211 (3) ◽  
pp. 943-961 ◽  
Author(s):  
John K. Kelly ◽  
Kimberly A. Hughes
Keyword(s):  
Balancing Selection ◽  
Parallel Evolution ◽  
Rapid Evolution ◽  
Natural Populations ◽  
Intermediate Frequency ◽  
Drosophila Simulans ◽  
Data Sets ◽  
Sequencing Data ◽  
Simulation Tools ◽  
Genome Wide

We develop analytical and simulation tools for evolve-and-resequencing experiments and apply them to a new study of rapid evolution in Drosophila simulans. Likelihood test statistics applied to pooled population sequencing data suggest parallel evolution of 138 SNPs across the genome. This number is reduced by orders of magnitude from previous studies (thousands or tens of thousands), owing to differences in both experimental design and statistical analysis. Whole genome simulations calibrated from Drosophila genetic data sets indicate that major features of the genome-wide response could be explained by as few as 30 loci under strong directional selection with a corresponding hitchhiking effect. Smaller effect loci are likely also responding, but are below the detection limit of the experiment. Finally, SNPs showing strong parallel evolution in the experiment are intermediate in frequency in the natural population (usually 30–70%) indicative of balancing selection in nature. These loci also exhibit elevated differentiation among natural populations of D. simulans, suggesting environmental heterogeneity as a potential balancing mechanism.

scholarly journals Karyotype-environment associations support a role for a chromosomal inversion in local adaptation in the seaweed fly Coelopa frigida

2018 ◽  
Author(s):  
Claire Mérot ◽  
Emma Berdan ◽  
Charles Babin ◽  
Eric Normandeau ◽  
Maren Wellenreuther ◽  
...  
Keyword(s):  
North America ◽  
Local Adaptation ◽  
Environmental Gradients ◽  
Balancing Selection ◽  
Natural Populations ◽  
Inversion Polymorphism ◽  
Life History Strategies ◽  
Heterogeneous Environments ◽  
Adult Size ◽  
Coelopa Frigida

AbstractLarge chromosomal rearrangements are thought to facilitate adaptation to heterogeneous environments by limiting genomic recombination. Indeed, inversions have been implicated in adaptation along environmental clines and in ecotype specialisation. Here, we combine classical ecological studies and population genetics to investigate an inversion polymorphism previously documented in Europe among natural populations of the seaweed fly Coelopa frigida along a latitudinal cline in North America. We test if the inversion is present in North America and polymorphic, assess which environmental conditions modulate the inversion karyotype frequencies, and document the relationship between inversion karyotype and adult size. We sampled nearly 2,000 flies from 20 populations along several environmental gradients to quantify associations of inversion frequencies to heterogeneous environmental variables. Genotyping and phenotyping showed a widespread and conserved inversion polymorphism between Europe and America. Variation in inversion frequency was significantly associated with environmental factors, with parallel patterns between continents, indicating that the inversion may play a role in local adaptation. The three karyotypes of the inversion are differently favoured across micro-habitats and represent life-history strategies likely maintained by the collective action of several mechanisms of balancing selection. Our study adds to the mounting evidence that inversions are facilitators of adaptation and enhance within-species diversity.

scholarly journals Analysis of 427 genomes reveals moso bamboo population structure and genetic basis of property traits

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hansheng Zhao ◽  
Shuai Sun ◽  
Yulong Ding ◽  
Yue Wang ◽  
Xianghua Yue ◽  
...  
Keyword(s):  
Balancing Selection ◽  
Demographic History ◽  
Small Population ◽  
Moso Bamboo ◽  
Genomic Variation ◽  
Nucleotide Polymorphisms ◽  
Phylogenetic Groups ◽  
Low Genetic Diversity ◽  
Genetic Mechanisms ◽  
Whole Genome Resequencing

AbstractMoso bamboo (Phyllostachys edulis) is an economically and ecologically important nontimber forestry species. Further development of this species as a sustainable bamboo resource has been hindered by a lack of population genome information. Here, we report a moso bamboo genomic variation atlas of 5.45 million single-nucleotide polymorphisms (SNPs) from whole-genome resequencing of 427 individuals covering 15 representative geographic areas. We uncover low genetic diversity, high genotype heterozygosity, and genes under balancing selection underlying moso bamboo population adaptation. We infer its demographic history with one bottleneck and its recently small population without a rebound. We define five phylogenetic groups and infer that one group probably originated by a single-origin event from East China. Finally, we conduct genome-wide association analysis of nine important property-related traits to identify candidate genes, many of which are involved in cell wall, carbohydrate metabolism, and environmental adaptation. These results provide a foundation and resources for understanding moso bamboo evolution and the genetic mechanisms of agriculturally important traits.

Nucleotide polymorphisms in three genes support host and geographic speciation in tree pathogens belonging toGremmeniellaspp.

2002 ◽  
Vol 80 (11) ◽  
pp. 1151-1159 ◽  
Author(s):  
M Dusabenyagasani ◽  
G Laflamme ◽  
R C Hamelin
Keyword(s):  
North America ◽  
Dna Sequences ◽  
North American ◽  
Abies Balsamea ◽  
Host Specialization ◽  
Rrna Genes ◽  
Nucleotide Polymorphisms ◽  
Group I ◽  
Geographic Separation ◽  
Pinus Spp

We detected nucleotide polymorphisms within the genus Gremmeniella in DNA sequences of β-tubulin, glyceraldehyde phosphate dehydrogenase, and mitochondrial small subunit rRNA (mtSSU rRNA) genes. A group-I intron was present in strains originating from fir (Abies spp.) in the mtSSU rRNA locus. This intron in the mtSSU rRNA locus of strains isolated from Abies sachalinensis (Fridr. Schmidt) M.T. Mast in Asia was also found in strains isolated from Abies balsamea (L.) Mill. in North America. Phylogenetic analyses yielded trees that grouped strains by host of origin with strong branch support. Asian strains of Gremmeniella abietina (Lagerberg) Morelet var. abietina isolated from fir (A. sachalinensis) were more closely related to G. abietina var. balsamea from North America, which is found on spruce (Picea spp.) and balsam fir, and European and North American races of G. abietina var. abietina from pines (Pinus spp.) were distantly related. Likewise, North American isolates of Gremmeniella laricina (Ettinger) O. Petrini, L.E. Petrini, G. Laflamme, & G.B. Ouellette, a pathogen of larch, was more closely related to G. laricina from Europe than to G. abietina var. abietina from North America. These data suggest that host specialization might have been the leading evolutionary force shaping Gremmeniella spp., with geographic separation acting as a secondary factor.Key words: Gremmeniella, geographic separation, host specialization, mitochondrial rRNA, nuclear genes.

scholarly journals Unexpected genomic, biosynthetic and species diversity of Streptomyces bacteria from bats in Arizona and New Mexico, USA

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Cooper J. Park ◽  
Nicole A. Caimi ◽  
Debbie C. Buecher ◽  
Ernest W. Valdez ◽  
Diana E. Northup ◽  
...  
Keyword(s):  
New Mexico ◽  
Genetic Manipulation ◽  
Distinct Species ◽  
Biosynthetic Gene Cluster ◽  
Genomic Variation ◽  
Species Variation ◽  
Nucleotide Polymorphisms ◽  
Peptide Synthetases ◽  
Genome Wide ◽  
Diversity Estimates

Abstract Background Antibiotic-producing Streptomyces bacteria are ubiquitous in nature, yet most studies of its diversity have focused on free-living strains inhabiting diverse soil environments and those in symbiotic relationship with invertebrates. Results We studied the draft genomes of 73 Streptomyces isolates sampled from the skin (wing and tail membranes) and fur surfaces of bats collected in Arizona and New Mexico. We uncovered large genomic variation and biosynthetic potential, even among closely related strains. The isolates, which were initially identified as three distinct species based on sequence variation in the 16S rRNA locus, could be distinguished as 41 different species based on genome-wide average nucleotide identity. Of the 32 biosynthetic gene cluster (BGC) classes detected, non-ribosomal peptide synthetases, siderophores, and terpenes were present in all genomes. On average, Streptomyces genomes carried 14 distinct classes of BGCs (range = 9–20). Results also revealed large inter- and intra-species variation in gene content (single nucleotide polymorphisms, accessory genes and singletons) and BGCs, further contributing to the overall genetic diversity present in bat-associated Streptomyces. Finally, we show that genome-wide recombination has partly contributed to the large genomic variation among strains of the same species. Conclusions Our study provides an initial genomic assessment of bat-associated Streptomyces that will be critical to prioritizing those strains with the greatest ability to produce novel antibiotics. It also highlights the need to recognize within-species variation as an important factor in genetic manipulation studies, diversity estimates and drug discovery efforts in Streptomyces.

Multilocus Sequence Analysis and Copper Ion Resistance Detection of 60 Xanthomonas arboricola pv. juglandis Isolates from China

Plant Disease ◽  
2021 ◽  
Author(s):  
Benzhong Fu ◽  
Jieqian Zhu ◽  
Conard Lee ◽  
Lihua Wang
Keyword(s):  
Sequence Analysis ◽  
Copper Ion ◽  
Housekeeping Genes ◽  
Threshold Value ◽  
Pcr Primers ◽  
Multilocus Sequence Analysis ◽  
Nucleotide Polymorphisms ◽  
Specific Pcr ◽  
Resistant Strains ◽  
Xanthomonas Arboricola

Walnut bacterial blight caused by Xanthomonas arboricola pv. juglandis (Xaj) has serious repercussions for walnut production around the world. Between 2015 and 2017, disease samples were collected from six counties (Danjiangkou, Baokang, Suizhou, Shennongjia, Zigui, and Xingshan) in Hubei province, China. Fifty-nine Xaj strains were identified by morphology and specific PCR primers from 206 isolates. The genetic diversity of 60 Xaj strains (59 from Hubei plus one from Beijing) was evaluated by Multilocus Sequence Analysis (MLST), and their resistance to copper ion (Cu2+) treatment was determined. A Neighbor Joining phylogenetic dendrogram was constructed based on four sequences of housekeeping genes (atpD-dnaK-glnA-gyrB). Two groups of strains were identified whose clustering was consistent with that of glnA. The minimal inhibitory concentration of copper ion on representative Xaj strain DW3F3 (the first genome sequenced Xaj from China) was 115 μg/ml. Setting the copper resistant threshold value to 125 μg/ml, 47 and 13 strains were considered sensitive and resistant to Cu2+, respectively. Furthermore, five strains showed Cu2+ resistance at 270 μg/ml. Compared to the copB from sensitive strains, the copB gene in resistant strains had a 15-bp insertion and eight scattered single nucleotide polymorphisms. Interestingly, the clustering based on MLSA was distinct between Xaj copper ion resistant and sensitive strains.

scholarly journals Population Genetics and Evolution Analysis Reveal Diversity and Origin of Ammopiptanthus in China.

2021 ◽  
Author(s):  
Guai-qiang Chai ◽  
Yizhong Duan ◽  
Peipei Jiao ◽  
Zhongyu Du ◽  
Furen Kang
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Association Studies ◽  
Natural Populations ◽  
Principal Component ◽  
Nucleotide Polymorphisms ◽  
Future Design ◽  
Ammopiptanthus Nanus ◽  
Genome Wide

Abstract Background：Elucidating and revealing the population genetic structure, genetic diversity and recombination is essential for understanding the evolution and adaptation of species. Ammopiptanthus, which is an endangered survivor from the Tethys in the Tertiary Period, is the only evergreen broadleaf shrub grown in Northwest of China. However, little is known about its genetic diversity and underlying adaptation mechanisms. Results：Here, 111 Ammopiptanthus individuals collected from fifteen natural populations in estern China were analyzed by means of the specific locus amplified fragment sequencing (SLAF-seq). Based on the single nucleotide polymorphisms (SNPs) and insertions and deletions (InDels) detected by SLAF-seq, genetic diversity and markers associated with climate and geographical distribution variables were identified. The results of genetic diversity and genetic differentiation revealed that all fifteen populations showed medium genetic diversity, with PIC values ranging from 0.1648 to 0.3081. AMOVA and Fst indicated that a low genetic differentiation existed among populations. Phylogenetic analysis showed that NX-BG and NMG-DQH of fifteen populations have the highest homology，while the genetic structure analysis revealed that these Ammopiptanthus germplasm accessions were structured primarily along the basis of their geographic collection, and that an extensive admixture occurred in each group. In addition, the genome-wide linkage disequilibrium (LD) and principal component analysis showed that Ammopiptanthus nanus had a more diverse genomic background, and all genetic populations were clearly distinguished, although different degrees of introgression were detected in these groups. Conclusion：Our study could provide guidance to the future design of association studies and the systematic utilization and protection of the genetic variation characterizing the Ammopiptanthus.

scholarly journals Genomic Variation between PRSV Resistant Transgenic SunUp and Its Progenitor Cultivar Sunset

2020 ◽  
Author(s):  
Jingping Fang ◽  
Andrew Wood ◽  
Youqiang Chen ◽  
Jingjing Yue ◽  
Ray Ming
Keyword(s):  
Spontaneous Mutation ◽  
Nuclear Genome ◽  
Plastid Dna ◽  
High Impact ◽  
Genomic Variation ◽  
Reliable Estimate ◽  
Nucleotide Polymorphisms ◽  
Structural Variations ◽  
Transgenic Papaya ◽  
Organelle Genomes

Abstract Background: The safety of genetically transformed plants remains a subject of scrutiny. Genomic variants in PRSV resistant transgenic papaya will provide evidence to rationally address such concerns. Results: In this study, a total of more than 74 million Illumina reads for progenitor ‘Sunset’ were mapped onto transgenic papaya ‘SunUp’ reference genome. 310,364 single nucleotide polymorphisms (SNPs), 34,071 small Inserts/deletions (InDels) and 1,200 large structural variations (SVs) were detected between ‘Sunset’ and ‘SunUp’. Those variations have an uneven distribution across nine chromosomes in papaya. Only 0.27% of mutations were predicted to be high-impact mutations. ATP-related categories were highly enriched among these high-impact genes. The SNP mutation rate was about 8.4×10-4 per site, comparable with the rate induced by spontaneous mutation over numerous generations. The transition-to-transversion ratio was 1.439 and the predominant mutations were C/G to T/A transitions. Spontaneous mutations were the leading cause of SNPs in transgenic papaya ‘SunUp’. A total of 3,430 nuclear plastid DNA (NUPT) and 2,764 nuclear mitochondrial DNA (NUMT) junction sites have been found in ‘SunUp’, which is proportionally higher than the predicted total NUPT and NUMT junction sites in ‘Sunset’ (3,346 and 2,745, respectively). Among all nuclear organelle DNA (norgDNA) junction sites, 96% of junction sites were shared by ‘SunUp’ and ‘Sunset’. The average identity between ‘SunUp’ specific norgDNA and corresponding organelle genomes was higher than that of norgDNA shared by ‘SunUp’ and ‘Sunset’. Six ‘SunUp’ organelle-like borders of transgenic insertions were nearly identical to corresponding sequences in organelle genomes (98.18~100%). None of the paired-end spans of mapped ‘Sunset’ reads were elongated by any ‘SunUp’ transformation plasmid derived inserts. Significant amounts of DNA were transferred from organelles to the nuclear genome during bombardment, including the six flanking sequences of the three transgenic insertions.Conclusions: Comparative whole-genome analyses between ‘SunUp’ and ‘Sunset’ provide a reliable estimate of genome-wide variations and evidence of organelle-to-nucleus transfer of DNA associated with biolistic transformation.

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