scholarly journals The alternative reality of plant mitochondrial DNA

2019 ◽  
Author(s):  
Alexander Kozik ◽  
Beth A. Rowan ◽  
Dean Lavelle ◽  
Lidija Berke ◽  
M. Eric Schranz ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Genome Structure ◽  
Structural Diversity ◽  
Data Availability ◽  
Mitochondrial Genomes ◽  
Physical Analysis ◽  
Sequencing Data ◽  
True Nature ◽  
Plant Mitochondrial Dna ◽  
Long Read

ABSTRACTPlant mitochondrial genomes are usually assembled and displayed as circular maps based on the widely-held assumption that circular genome molecules are the primary form of mitochondrial DNA, despite evidence to the contrary. Many plant mitochondrial genomes have one or more pairs of large repeats that can act as sites for inter- or intramolecular recombination, leading to multiple alternative genomic arrangements (isoforms). Most mitochondrial genomes have been assembled using methods that were unable to capture the complete spectrum of isoforms within a species, leading to an incomplete inference of their structure and recombinational activity. To document and investigate underlying reasons for structural diversity in plant mitochondrial DNA, we used long-read (PacBio) and short-read (Illumina) sequencing data to assemble and compare mitochondrial genomes of domesticated (Lactuca sativa) and wild (L. saligna and L. serriola) lettuce species. This allowed us to characterize a comprehensive, complex set of isoforms within each species and to compare genome structures between species. Physical analysis of L. sativa mtDNA molecules by fluorescence microscopy revealed a variety of linear, branched linear, and circular structures. The mitochondrial genomes for L. sativa and L. serriola were identical in sequence and arrangement, and differed substantially from L. saligna, indicating that the mitochondrial genome structure did not change during domestication. From the isoforms evident in our data, we inferred that recombination occurs at repeats of all sizes at variable frequencies. The differences in genome structure between L. saligna and the two other lettuce species can be largely explained by rare recombination events that rearrange the structure. Our data demonstrate that representations of plant mitochondrial DNA as simple, genome-sized circular molecules are not accurate descriptions of their true nature and that in reality plant mitochondrial DNA is a complex, dynamic mixture of forms.Data AvailabilityBioProject: Organellar genomes of cultivated and wild lettuce (Lactuca) varieties PRJNA508811 https://www.ncbi.nlm.nih.gov/bioproject/508811 and other accessions as indicated through the text and supplemental data.FundingNSF grant MCB-1413152 to ACC and support from UC Davis to RWM.

scholarly journals Highly accurate long-read HiFi sequencing data for five complex genomes

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Ting Hon ◽  
Kristin Mars ◽  
Greg Young ◽  
Yu-Chih Tsai ◽  
Joseph W. Karalius ◽  
...  
Keyword(s):  
Sequence Data ◽  
Genome Structure ◽  
Data Sets ◽  
Sequencing Data ◽  
Complex Samples ◽  
Bioinformatic Tools ◽  
Long Reads ◽  
Sequencing Method ◽  
Sample Data ◽  
Long Read

AbstractThe PacBio® HiFi sequencing method yields highly accurate long-read sequencing datasets with read lengths averaging 10–25 kb and accuracies greater than 99.5%. These accurate long reads can be used to improve results for complex applications such as single nucleotide and structural variant detection, genome assembly, assembly of difficult polyploid or highly repetitive genomes, and assembly of metagenomes. Currently, there is a need for sample data sets to both evaluate the benefits of these long accurate reads as well as for development of bioinformatic tools including genome assemblers, variant callers, and haplotyping algorithms. We present deep coverage HiFi datasets for five complex samples including the two inbred model genomes Mus musculus and Zea mays, as well as two complex genomes, octoploid Fragaria × ananassa and the diploid anuran Rana muscosa. Additionally, we release sequence data from a mock metagenome community. The datasets reported here can be used without restriction to develop new algorithms and explore complex genome structure and evolution. Data were generated on the PacBio Sequel II System.

scholarly journals Resolving Complex Structural Genomic Rearrangements using a Randomized Approach

2015 ◽  
Author(s):  
Xuefang Zhao ◽  
Sarah B. Emery ◽  
Bridget Myers ◽  
Jeffrey M. Kidd ◽  
Ryan E. Mills
Keyword(s):  
Chromosomal Rearrangements ◽  
Genome Structure ◽  
Genomic Rearrangements ◽  
Sequencing Data ◽  
Genomic Alterations ◽  
Structural Genomic ◽  
Homologous Chromosomes ◽  
Complex Chromosomal Rearrangements ◽  
Long Read ◽  
Complex Structural

Complex chromosomal rearrangements consist of structural genomic alterations involving multiple instances of deletions, duplications, inversions, or translocations that co-occur either on the same chromosome or represent different overlapping events on homologous chromosomes. We present SVelter, an algorithm that first identifies regions of the genome suspected to harbor a complex event and then iteratively rearranges the local genome structure, in a randomized fashion, with each structure scored against characteristics of the observed sequencing data. We show that SVelter is able to accurately reconstruct these regions when compared to well-characterized genomes that have been deep sequenced with both short and long read technologies.

scholarly journals Long-read assemblies reveal structural diversity in genomes of organelles - an example with Acacia pycnantha

2020 ◽  
Author(s):  
Anna E. Syme ◽  
Todd G.B. McLay ◽  
Frank Udovicic ◽  
David J. Cantrill ◽  
Daniel J. Murphy
Keyword(s):  
Mitochondrial Genome ◽  
Chloroplast Genome ◽  
De Novo ◽  
Genomic Structure ◽  
Structural Diversity ◽  
Mitochondrial Genomes ◽  
Long Reads ◽  
Organelle Genomes ◽  
Long Read ◽  
Assembly Algorithms

AbstractAlthough organelle genomes are typically represented as single, static, circular molecules, there is evidence that the chloroplast genome exists in two structural haplotypes and that the mitochondrial genome can display multiple circular, linear or branching forms. We sequenced and assembled chloroplast and mitochondrial genomes of the Golden Wattle, Acacia pycnantha, using long reads, iterative baiting to extract organelle-only reads, and several assembly algorithms to explore genomic structure. Using a de novo assembly approach agnostic to previous hypotheses about structure, we found different assemblies revealed contrasting arrangements of genomic segments; a hypothesis supported by mapped reads spanning alternate paths.

scholarly journals A new method for long-read sequencing of animal mitochondrial genomes: application to the identification of equine mitochondrial DNA variants

2019 ◽  
Author(s):  
Sophie Dhorne-Pollet ◽  
Eric Barrey ◽  
Nicolas Pollet
Keyword(s):  
Mitochondrial Dna ◽  
Nuclear Dna ◽  
Multiple Displacement Amplification ◽  
Mitochondrial Genomes ◽  
Sequencing Technology ◽  
Long Reads ◽  
Selective Elimination ◽  
Long Read ◽  
Variant Analysis ◽  
Mitochondrial Dna Variants

AbstractBackgroundWe present here an approach to sequence whole mitochondrial genomes using nanopore long-read sequencing. Our method relies on the selective elimination of nuclear DNA using an exonuclease treatment and on the amplification of circular mitochondrial DNA using a multiple displacement amplification step.ResultsWe optimized each preparative step to obtain a 100 million-fold enrichment of horse mitochondrial DNA relative to nuclear DNA. We sequenced these amplified mitochondrial DNA using nanopore sequencing technology and obtained mitochondrial DNA reads that represented up to half of the sequencing output. The sequence reads were 2.3 kb of mean length and provided an even coverage of the mitochondrial genome. Long-reads spanning half or more of the whole mtDNA provided a coverage that varied between 118X and 488X. Finally, we identified SNPs with a precision of 98.1%; recall of 85.2% and a F1-score of 0.912.ConclusionsOur analyses show that our method to amplify mtDNA and to sequence it using the nanopore technology is usable for mitochondrial DNA variant analysis. With minor modifications, this approach could easily be applied to other large circular DNA molecules.

scholarly journals Long-read sequencing reveals atypical mitochondrial genome structure in a New Zealand marine isopod

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
William S. Pearman ◽  
Sarah J. Wells ◽  
James Dale ◽  
Olin K. Silander ◽  
Nikki E. Freed
Keyword(s):  
New Zealand ◽  
Mitochondrial Genome ◽  
Dna Sequencing ◽  
Recent Work ◽  
Genome Structure ◽  
Mitochondrial Genomes ◽  
Short Read ◽  
Mitochondrial Structure ◽  
Evolutionary Origins ◽  
Long Read

Most animal mitochondrial genomes are small, circular and structurally conserved. However, recent work indicates that diverse taxa possess unusual mitochondrial genomes. In Isopoda , species in multiple lineages have atypical and rearranged mitochondrial genomes. However, more species of this speciose taxon need to be evaluated to understand the evolutionary origins of atypical mitochondrial genomes in this group. In this study, we report the presence of an atypical mitochondrial structure in the New Zealand endemic marine isopod, Isocladus armatus. Data from long- and short-read DNA sequencing suggest that I. armatus has two mitochondrial chromosomes. The first chromosome consists of two mitochondrial genomes that have been inverted and fused together in a circular form, and the second chromosome consists of a single mitochondrial genome in a linearized form. This atypical mitochondrial structure has been detected in other isopod lineages, and our data from an additional divergent isopod lineage (Sphaeromatidae) lends support to the hypothesis that atypical structure evolved early in the evolution of Isopoda . Additionally, we find that an asymmetrical site previously observed across many species within Isopoda is absent in I. armatus , but confirm the presence of two asymmetrical sites recently reported in two other isopod species.

The plant mitochondrial genome: homologous recombination as a mechanism for generating heterogeneity

1988 ◽  
Vol 319 (1193) ◽  
pp. 149-163 ◽  
Keyword(s):  
Mitochondrial Dna ◽  
Homologous Recombination ◽  
Mitochondrial Genome ◽  
Higher Plants ◽  
Genome Structure ◽  
Rapid Evolution ◽  
Mitochondrial Genomes ◽  
Base Sequence ◽  
Plant Mitochondrial Genome ◽  
Organelle Genomes

The mitochondrial genomes of higher plants are among the largest and most complex organelle genomes described. They are generally multicircular or partly linear; in some species, extrachromosomal plasmids are present. It is proposed that inter- and intramolecular homologous recombination can account for the diversity of the observed genome organizations. The ability of mitochondria to fuse establishes a panmictic mitochondrial DNA population which is in recombinational equilibrium. It is suggested that this suppresses the base mutation rate, and unequal partitioning of the cytoplasm during cell division can lead to the rapid evolution of mitochondrial genome structure. This contrasts with the observed rates of base-sequence and genome evolution in chloroplasts. This difference can be accounted for solely by the inability of chloroplasts to fuse, thereby preventing chloroplast genome panmixis.

scholarly journals Long-read Data Revealed Structural Diversity in Human Centromere Sequences

2019 ◽  
Author(s):  
Yuta Suzuki ◽  
Gene Myers ◽  
Shinichi Morishita
Keyword(s):  
Dna Sequences ◽  
Structural Diversity ◽  
Higher Order ◽  
Human Populations ◽  
Sequence Evolution ◽  
Single Nucleotide Variants ◽  
True Nature ◽  
Human Centromere ◽  
Long Read ◽  
Novel Variant

ABSTRACTCentromeres invariably serve as the loci of kinetochore assembly in all eukaryotic cells, but their underlying DNA sequences evolve rapidly. Human centromeres are characterized by their extremely repetitive structures, i.e., higher-order repeats, rendering the region one of the most difficult parts of the genome to assess. Consequently, our understanding of centromere sequence variations across human populations is limited. Here, we analyzed chromosomes 11, 17, and X using long sequencing reads of two European and two Asian genomes, and our results show that human centromere sequences exhibit substantial structural diversity, harboring many novel variant higher-order repeats specific to individuals, while frequent single-nucleotide variants are largely conserved. Our findings add another dimension to our knowledge of centromeres, challenging the notion of stable human centromeres. The discovery of such diversity prompts further deep sequencing of human populations to understand the true nature of sequence evolution in human centromeres.

scholarly journals Highly accurate long-read HiFi sequencing data for five complex genomes

2020 ◽  
Author(s):  
Ting Hon ◽  
Kristin Mars ◽  
Greg Young ◽  
Yu-Chih Tsai ◽  
Joseph W. Karalius ◽  
...  
Keyword(s):  
Sequence Data ◽  
Genome Structure ◽  
Data Sets ◽  
Sequencing Data ◽  
Complex Samples ◽  
Bioinformatic Tools ◽  
Long Reads ◽  
Sequencing Method ◽  
Sample Data ◽  
Long Read

AbstractThe PacBio® HiFi sequencing method yields highly accurate long-read sequencing datasets with read lengths averaging 10-25 kb and accuracies greater than 99.5%. These accurate long reads can be used to improve results for complex applications such as single nucleotide and structural variant detection, genome assembly, assembly of difficult polyploid or highly repetitive genomes, and assembly of metagenomes. Currently, there is a need for sample data sets to both evaluate the benefits of these long accurate reads as well as for development of bioinformatic tools including genome assemblers, variant callers, and haplotyping algorithms. We present deep coverage HiFi datasets for five complex samples including the two inbred model genomes Mus musculus and Zea mays, as well as two complex genomes, octoploid Fragaria × ananassa and the diploid anuran Rana muscosa. Additionally, we release sequence data from a mock metagenome community. The datasets reported here can be used without restriction to develop new algorithms and explore complex genome structure and evolution. Data were generated on the PacBio Sequel II System.

scholarly journals Long read sequencing reveals atypical mitochondrial genome structure in a New Zealand marine isopod

2021 ◽  
Author(s):  
William S Pearman ◽  
Sarah J Wells ◽  
James Dale ◽  
Olin K Silander ◽  
Nikki E Freed
Keyword(s):  
New Zealand ◽  
Mitochondrial Genome ◽  
Dna Sequencing ◽  
Recent Work ◽  
Genome Structure ◽  
Mitochondrial Genomes ◽  
Short Read ◽  
Mitochondrial Structure ◽  
Evolutionary Origins ◽  
Long Read

Most animal mitochondrial genomes are small, circular, and structurally conserved. However, recent work indicates that diverse taxa possess unusual mitochondrial genomes. In Isopoda, species in multiple lineages have atypical and rearranged mitochondrial genomes. However, more species of this speciose taxon need to be evaluated to understand the evolutionary origins of atypical mitochondrial genomes in this group. In this study, we report the presence of an atypical mitochondrial structure in the New Zealand endemic marine isopod, Isocladus armatus. Data from long and short read DNA sequencing, suggests that I. armatus has two mitochondrial chromosomes. The first chromosome consists of two mitochondrial genomes that have been inverted and fused together in a circular form, and the second chromosome consists of a single mitochondrial genome in a linearized form. This atypical mitochondrial structure has been detected in other isopod lineages, and our data from an additional divergent isopod lineage (Sphaeromatidae) lends support to the hypothesis that atypical structure evolved early in the evolution of Isopoda. Additionally, we find that a heteroplasmic site previously observed across many species within Isopoda is absent in I. armatus, but confirm the presence of two heteroplasmic sites recently reported in two other isopod species.

scholarly journals A new method for long-read sequencing of animal mitochondrial genomes: application to the identification of equine mitochondrial DNA variants

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Sophie Dhorne-Pollet ◽  
Eric Barrey ◽  
Nicolas Pollet
Keyword(s):  
Mitochondrial Dna ◽  
Nuclear Dna ◽  
Multiple Displacement Amplification ◽  
Variant Calling ◽  
Ground Truth ◽  
Mitochondrial Genomes ◽  
Long Reads ◽  
Long Read ◽  
Variant Analysis ◽  
Mitochondrial Dna Variants

Abstract Background Mitochondrial DNA is remarkably polymorphic. This is why animal geneticists survey mitochondrial genomes variations for fundamental and applied purposes. We present here an approach to sequence whole mitochondrial genomes using nanopore long-read sequencing. Our method relies on the selective elimination of nuclear DNA using an exonuclease treatment and on the amplification of circular mitochondrial DNA using a multiple displacement amplification step. Results We optimized each preparative step to obtain a 100 million-fold enrichment of horse mitochondrial DNA relative to nuclear DNA. We sequenced these amplified mitochondrial DNA using nanopore sequencing technology and obtained mitochondrial DNA reads that represented up to half of the sequencing output. The sequence reads were 2.3 kb of mean length and provided an even coverage of the mitochondrial genome. Long-reads spanning half or more of the whole mtDNA provided a coverage that varied between 118X and 488X. We evaluated SNPs identified using these long-reads by Sanger sequencing as ground truth and found a precision of 100.0%; a recall of 93.1% and a F1-score of 0.964 using the Twilight horse mtDNA reference. The choice of the mtDNA reference impacted variant calling efficiency with F1-scores varying between 0.947 and 0.964. Conclusions Our method to amplify mtDNA and to sequence it using the nanopore technology is usable for mitochondrial DNA variant analysis. With minor modifications, this approach could easily be applied to other large circular DNA molecules.

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