scholarly journals Long-read sequencing uncovers the adaptive topography of a carnivorous plant genome

2017 ◽  
Vol 114 (22) ◽  
pp. E4435-E4441 ◽  
Author(s):  
Tianying Lan ◽  
Tanya Renner ◽  
Enrique Ibarra-Laclette ◽  
Kimberly M. Farr ◽  
Tien-Hao Chang ◽  
...  
Keyword(s):  
Genome Structure ◽  
Nuclear Genome ◽  
Carnivorous Plant ◽  
Plant Genome ◽  
Peptide Transport ◽  
Special Importance ◽  
Specific Expression ◽  
Gene Copies ◽  
Duplication Events ◽  
Syntenic Gene

Utricularia gibba, the humped bladderwort, is a carnivorous plant that retains a tiny nuclear genome despite at least two rounds of whole genome duplication (WGD) since common ancestry with grapevine and other species. We used a third-generation genome assembly with several complete chromosomes to reconstruct the two most recent lineage-specific ancestral genomes that led to the modern U. gibba genome structure. Patterns of subgenome dominance in the most recent WGD, both architectural and transcriptional, are suggestive of allopolyploidization, which may have generated genomic novelty and led to instantaneous speciation. Syntenic duplicates retained in polyploid blocks are enriched for transcription factor functions, whereas gene copies derived from ongoing tandem duplication events are enriched in metabolic functions potentially important for a carnivorous plant. Among these are tandem arrays of cysteine protease genes with trap-specific expression that evolved within a protein family known to be useful in the digestion of animal prey. Further enriched functions among tandem duplicates (also with trap-enhanced expression) include peptide transport (intercellular movement of broken-down prey proteins), ATPase activities (bladder-trap acidification and transmembrane nutrient transport), hydrolase and chitinase activities (breakdown of prey polysaccharides), and cell-wall dynamic components possibly associated with active bladder movements. Whereas independently polyploid Arabidopsis syntenic gene duplicates are similarly enriched for transcriptional regulatory activities, Arabidopsis tandems are distinct from those of U. gibba, while still metabolic and likely reflecting unique adaptations of that species. Taken together, these findings highlight the special importance of tandem duplications in the adaptive landscapes of a carnivorous plant genome.

scholarly journals Two ancient genome duplication events shape diversity in Hibiscus L. (Malvaceae)

2020 ◽  
Author(s):  
Jonna Sofia Eriksson ◽  
Christine D. Bacon ◽  
Dominic J. Bennett ◽  
Bernard E. Pfeil ◽  
Bengt Oxelman ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Genome Size ◽  
Genome Duplication ◽  
Single Copy ◽  
Genomic Diversity ◽  
Plant Genome ◽  
Genome Doubling ◽  
Gene Copies ◽  
Plant Groups ◽  
Duplication Events

Abstract Background: The great diversity in plant genome size and chromosome number is partly due to polyploidization (i.e., genome doubling events). The differences in genome size and chromosome number among diploid plant species can be a window into the intriguing phenomenon of past genome doubling that may be obscured through time by the process of diploidization. The genus Hibiscus L. (Malvaceae) has a wide diversity of chromosome numbers and an allegedly complex genomic history. Hibiscus is ideal for exploring past genomic events because although two ancient genome duplication events have been identified, as more are still likely to be found, considering its diverse background. To reappraise the group’s genomic history, we tested a series of scenarios describing different polyploidization events using previously identified duplications in Hibiscus syriacus.Results: The data showed that >54% of the single-copy genes where in fact paralogues. When testing for different genome duplication scenarios using gene count data; species of Hibiscus was shown to have shared one genome duplication with H. syriacus, -- while one whole genome duplication was contained within H. syriacus, -- to be the preferred model given the observed distribution of paralogous gene copies in Hibiscus.Conclusions: Here, we corroborated the independent genome doubling previously found in the lineage leading to H. syriacus and a shared genome doubling of this lineage and the remainder of Hibiscus. Additionally, we found a previously undiscovered genome duplication shared by the /Pavonia and /Malvaviscus clades (both nested within Hibiscus) with the occurrences of two copies in what were otherwise single-copy genes. Our results highlight the complexity of genomic diversity in some plant groups, which makes orthology assessment and accurate phylogenomic inference difficult.

scholarly journals Nuclear-cytoplasmic balance: whole genome duplications induce elevated organellar genome copy number

2021 ◽  
Author(s):  
Matheus Fernandes Gyorfy ◽  
Emma R Miller ◽  
Justin L Conover ◽  
Corrinne E Grover ◽  
Jonathan F Wendel ◽  
...  
Keyword(s):  
Copy Number ◽  
Nuclear Genome ◽  
Plant Genome ◽  
Whole Genome ◽  
Genome Copy ◽  
Relative Copy Number ◽  
Organellar Genome ◽  
Plastid Genomes ◽  
Copy Numbers ◽  
Genome Copy Number

The plant genome is partitioned across three distinct subcellular compartments: the nucleus, mitochondria, and plastids. Successful coordination of gene expression among these organellar genomes and the nuclear genome is critical for plant function and fitness. Whole genome duplication events (WGDs) in the nucleus have played a major role in the diversification of land plants and are expected to perturb the relative copy number (stoichiometry) of nuclear, mitochondrial, and plastid genomes. Thus, elucidating the mechanisms whereby plant cells respond to the cytonuclear stoichiometric imbalance that follow WGDs represents an important yet underexplored question in understanding the evolutionary consequences of genome doubling. We used droplet digital PCR (ddPCR) to investigate the relationship between nuclear and organellar genome copy numbers in allopolyploids and their diploid progenitors in both wheat and Arabidopsis. Polyploids exhibit elevated organellar genome copy numbers per cell, largely preserving the cytonuclear stoichiometry observed in diploids despite the change in nuclear genome copy number. To investigate the timescale over which cytonuclear stoichiometry may respond to WGD, we also estimated organellar genome copy number in Arabidopsis synthetic autopolyploids and in a haploid-induced diploid line. We observed corresponding changes in organellar genome copy number in these laboratory-generated lines, indicating that at least some of the cellular response to cytonuclear stoichiometric imbalance is immediate following WGD. We conclude that increases in organellar genome copy numbers represent a common response to polyploidization, suggesting that maintenance of cytonuclear stoichiometry is an important component in establishing polyploid lineages.

scholarly journals Direct estimate of the spontaneous mutation rate uncovers the effects of drift and recombination in theChlamydomonas reinhardtiiplastid genome

2015 ◽  
Author(s):  
Rob W Ness ◽  
Susanne A Kraemer ◽  
Nick Colegrave ◽  
Peter D Keightley
Keyword(s):  
Mutation Rate ◽  
Genetic Drift ◽  
Plastid Genome ◽  
De Novo ◽  
Spontaneous Mutation ◽  
Genome Structure ◽  
Nuclear Genome ◽  
De Novo Mutation ◽  
Direct Estimate ◽  
Plastid Genomes

Plastids perform crucial cellular functions, including photosynthesis, across a wide variety of eukaryotes. Since endosymbiosis, plastids have maintained independent genomes that now display a wide diversity of gene content, genome structure, gene regulation mechanisms, and transmission modes. The evolution of plastid genomes depends on an input ofde novomutation, but our knowledge of mutation in the plastid is limited to indirect inference from patterns of DNA divergence between species. Here, we use a mutation accumulation experiment, where selection acting on mutations is rendered ineffective, combined with whole-plastid genome sequencing to directly characterize de novo mutation inChlamydomonas reinhardtii. We show that the mutation rates of the plastid and nuclear genomes are similar, but that the base spectra of mutations differ significantly. We integrate our measure of the mutation rate with a population genomic dataset of 20 individuals, and show that the plastid genome is subject to substantially stronger genetic drift than the nuclear genome. We also show that high levels of linkage disequilibrium in the plastid genome are not due to restricted recombination, but are instead a consequence of increased genetic drift. One likely explanation for increased drift in the plastid genome is that there are stronger effects of genetic hitchhiking. The presence of recombination in the plastid is consistent with laboratory studies inC. reinhardtiiand demonstrates that although the plastid genome is thought to be uniparentally inherited, it recombines in nature at a rate similar to the nuclear genome.

Perspectives on Allele-Specific Expression

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Siobhan Cleary ◽  
Cathal Seoighe
Keyword(s):  
Gene Expression ◽  
Genetic Variants ◽  
Data Science ◽  
Genetic Diseases ◽  
Annual Review ◽  
Publication Date ◽  
Biomedical Data ◽  
Specific Expression ◽  
Cis Acting ◽  
Gene Copies

Diploidy has profound implications for population genetics and susceptibility to genetic diseases. Although two copies are present for most genes in the human genome, they are not necessarily both active or active at the same level in a given individual. Genomic imprinting, resulting in exclusive or biased expression in favor of the allele of paternal or maternal origin, is now believed to affect hundreds of human genes. A far greater number of genes display unequal expression of gene copies due to cis-acting genetic variants that perturb gene expression. The availability of data generated by RNA sequencing applied to large numbers of individuals and tissue types has generated unprecedented opportunities to assess the contribution of genetic variation to allelic imbalance in gene expression. Here we review the insights gained through the analysis of these data about the extent of the genetic contribution to allelic expression imbalance, the tools and statistical models for gene expression imbalance, and what the results obtained reveal about the contribution of genetic variants that alter gene expression to complex human diseases and phenotypes. Expected final online publication date for the Annual Review of Biomedical Data Science, Volume 4 is July 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Constructing a Reference Genome in a Single Lab: The Possibility to Use Oxford Nanopore Technology

Plants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 270 ◽  
Author(s):  
Yun Gyeong Lee ◽  
Sang Chul Choi ◽  
Yuna Kang ◽  
Kyeong Min Kim ◽  
Chon-Sik Kang ◽  
...  
Keyword(s):  
Plant Species ◽  
Genome Sequencing ◽  
Reference Genome ◽  
Genome Structure ◽  
Plant Genome ◽  
Sequence Information ◽  
Sequencing Analysis ◽  
Oxford Nanopore ◽  
A Genome ◽  
Long Read

The whole genome sequencing (WGS) has become a crucial tool in understanding genome structure and genetic variation. The MinION sequencing of Oxford Nanopore Technologies (ONT) is an excellent approach for performing WGS and it has advantages in comparison with other Next-Generation Sequencing (NGS): It is relatively inexpensive, portable, has simple library preparation, can be monitored in real-time, and has no theoretical limits on reading length. Sorghum bicolor (L.) Moench is diploid (2n = 2x = 20) with a genome size of about 730 Mb, and its genome sequence information is released in the Phytozome database. Therefore, sorghum can be used as a good reference. However, plant species have complex and large genomes when compared to animals or microorganisms. As a result, complete genome sequencing is difficult for plant species. MinION sequencing that produces long-reads can be an excellent tool for overcoming the weak assembly of short-reads generated from NGS by minimizing the generation of gaps or covering the repetitive sequence that appears on the plant genome. Here, we conducted the genome sequencing for S. bicolor cv. BTx623 while using the MinION platform and obtained 895,678 reads and 17.9 gigabytes (Gb) (ca. 25× coverage of reference) from long-read sequence data. A total of 6124 contigs (covering 45.9%) were generated from Canu, and a total of 2661 contigs (covering 50%) were generated from Minimap and Miniasm with a Racon through a de novo assembly using two different tools and mapped assembled contigs against the sorghum reference genome. Our results provide an optimal series of long-read sequencing analysis for plant species while using the MinION platform and a clue to determine the total sequencing scale for optimal coverage that is based on various genome sizes.

scholarly journals Evolutionary Dynamics of Transposable Elements Following a Shared Polyploidization Event in the Tribe Andropogoneae

2020 ◽  
Vol 10 (12) ◽  
pp. 4387-4398
Author(s):  
Dhanushya Ramachandran ◽  
Michael R. McKain ◽  
Elizabeth A. Kellogg ◽  
Jennifer S. Hawkins
Keyword(s):  
Insertional Mutagenesis ◽  
Evolutionary Dynamics ◽  
Diploid Species ◽  
Duplicate Gene ◽  
Plant Genome ◽  
Abiotic Stress Response ◽  
Repeat Content ◽  
Gene Copies ◽  
Polyploidization Event ◽  
Plant Genome Evolution

Both polyploidization and transposable element (TE) activity are known to be major drivers of plant genome evolution. Here, we utilize the Zea-Tripsacum clade to investigate TE activity and accumulation after a shared polyploidization event. Comparisons of TE evolutionary dynamics in various Zea and Tripsacum species, in addition to two closely related diploid species, Urelytrum digitatum and Sorghum bicolor, revealed variation in repeat content among all taxa included in the study. The repeat composition of Urelytrum is more similar to that of Zea and Tripsacum compared to Sorghum, despite the similarity in genome size with the latter. Although LTR-retrotransposons were abundant in all species, we observed an expansion of the copia superfamily, specifically in Z. mays and T. dactyloides, species that have adapted to more temperate environments. Additional analyses of the genomic distribution of these retroelements provided evidence of biased insertions near genes involved in various biological processes including plant development, defense, and macromolecule biosynthesis. Specifically, copia insertions in Zea and T. dactyloides were significantly enriched near genes involved in abiotic stress response, suggesting independent evolution post Zea-Tripsacum divergence. The lack of copia insertions near the orthologous genes in S. bicolor suggests that duplicate gene copies generated during polyploidization may offer novel neutral sites for TEs to insert, thereby providing an avenue for subfunctionalization via TE insertional mutagenesis.

scholarly journals Repeated Evolution of Testis-Specific New Genes: The Case of Telomere-Capping Genes in Drosophila

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Raphaëlle Dubruille ◽  
Gabriel A. B. Marais ◽  
Benjamin Loppin
Keyword(s):  
Gene Family ◽  
Specific Expression ◽  
Functional Studies ◽  
Evolutionary Forces ◽  
New Genes ◽  
Male Gametes ◽  
Duplication Events ◽  
New Gene ◽  
Telomere Capping ◽  
Specific Expression Pattern

Comparative genome analysis has allowed the identification of various mechanisms involved in gene birth. However, understanding the evolutionary forces driving new gene origination still represents a major challenge. In particular, an intriguing and not yet fully understood trend has emerged from the study of new genes: many of them show a testis-specific expression pattern, which has remained poorly understood. Here we review the case of such a new gene, which involves a telomere-capping gene family in Drosophila. hiphop and its testis-specific paralog K81 are critical for the protection of chromosome ends in somatic cells and male gametes, respectively. Two independent functional studies recently proposed that these genes evolved under a reproductive-subfunctionalization regime. The 2011 release of new Drosophila genome sequences from the melanogaster group of species allowed us to deepen our phylogenetic analysis of the hiphop/K81 family. This work reveals an unsuspected dynamic of gene birth and death within the group, with recurrent duplication events through retroposition mechanisms. Finally, we discuss the plausibility of different evolutionary scenarios that could explain the diversification of this gene family.

scholarly journals Concerted evolution of human amylase genes.

1988 ◽  
Vol 8 (3) ◽  
pp. 1197-1205 ◽  
Author(s):  
D L Gumucio ◽  
K Wiebauer ◽  
R M Caldwell ◽  
L C Samuelson ◽  
M H Meisler
Keyword(s):  
Pancreatic Amylase ◽  
Amylase Gene ◽  
Salivary Amylase ◽  
Specific Expression ◽  
Enhancer Element ◽  
Tissue Specific ◽  
Tissue Specific Expression ◽  
Gene Copies ◽  
Amylase Genes ◽  
Sequence Elements

Cosmid clones containing 250 kilobases of genomic DNA from the human amylase gene cluster have been isolated. These clones contain seven distinct amylase genes which appear to comprise the complete multigene family. By sequence comparison with the cDNAs, we have identified two pancreatic amylase genes and three salivary amylase genes. Two truncated pseudogenes were also recovered. Intergenic distances of 17 to 22 kilobases separate the amylase gene copies. Within the past 10 million years, duplications, gene conversions, and unequal crossover events have resulted in a very high level of sequence similarity among human amylase gene copies. To identify sequence elements involved in tissue-specific expression and hormonal regulation, the promoter regions of the human amylase genes were sequenced and compared with those of the corresponding mouse genes. The promoters of the human and mouse pancreatic amylase genes are highly homologous between nucleotide -160 and the cap site. Two sequence elements thought to influence pancreas-specific expression of the rodent genes are present in the human genes. In contrast, similarity in the 5' flanking sequences of the salivary amylase genes is limited to several short sequence elements whose positions and orientations differ in the two species. Some of these sequence elements are also associated with other parotid-specific genes and may be involved in their tissue-specific expression. A glucocorticoid response element and a general enhancer element are closely associated in several of the amylase promoters.

scholarly journals Genome-wide and expression analysis of B-box gene family in pepper

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Jing Ma ◽  
Jia-xi Dai ◽  
Xiao-wei Liu ◽  
Duo Lin
Keyword(s):  
Transcription Factors ◽  
Abiotic Stress ◽  
Developmental Stages ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Transient Expression Assay ◽  
Specific Expression ◽  
Tissue Specific ◽  
Duplication Events ◽  
Onion Inner Epidermis

Abstract Background BBX transcription factors are a kind of zinc finger transcription factors with one or two B-box domains, which partilant in plant growth, development and response to abiotic or biotic stress. The BBX family has been identified in Arabidopsis, rice, tomato and some other model plant genomes. Results Here, 24 CaBBX genes were identified in pepper (Capsicum annuum L.), and the phylogenic analysis, structures, chromosomal location, gene expression patterns and subcellular localizations were also carried out to understand the evolution and function of CaBBX genes. All these CaBBXs were divided into five classes, and 20 of them distributed in 11 of 12 pepper chromosomes unevenly. Most duplication events occurred in subgroup I. Quantitative RT-PCR indicated that several CaBBX genes were induced by abiotic stress and hormones, some had tissue-specific expression profiles or differentially expressed at developmental stages. Most of CaBBX members were predicated to be nucleus-localized in consistent with the transient expression assay by onion inner epidermis of the three tested CaBBX members (CaBBX5, 6 and 20). Conclusion Several CaBBX genes were induced by abiotic stress and exogenous phytohormones, some expressed tissue-specific and variously at different developmental stage. The detected CaBBXs act as nucleus-localized transcription factors. Our data might be a foundation in the identification of CaBBX genes, and a further understanding of their biological function in future studies.

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