De novo transcriptome assembly, annotation, and identification of low-copy number genes in the flowering plant genus Silene (Caryophyllaceae)

2018 ◽  
Author(s):  
Yann J K Bertrand ◽  
Anna Petri ◽  
Anne-Cathrine Scheen ◽  
Mats Töpel ◽  
Bengt Oxelman

AbstractPhylogenetic methods that rely on information from multiple, unlinked genes have recently been developed for resolving complex situations where evolutionary relationships do not conform to bifurcated trees and are more adequately depicted by networks. Such situations arise when successive interspecific hybridizations in combination with genome duplications have shaped species phylogenies. Several processes such as homoeolog loss and deep coalescence can potentially hamper our ability to recover the historical signal correctly. Consequently the prospect of reconstructing accurate phylogenies lies in the combination of several low-copy nuclear markers that when, used in concert, can provide homoeologs for all the ancestral genomes and help to disentangle gene tree incongruence due to deep coalescence events. Expressed sequence tag (EST) databases represent valuable resource for the identification of genes in organisms with uncharacterized genomes and for development of molecular markers. The genus Silene L. is a prime example of a plant group whose evolutionary history involves numerous events of hybridization and polyploidization. As for many groups there is currently a shortage of low-copy nuclear markers, for which phylogenetic usefulness has been demonstrated. Here, we present two EST libraries for two species of Silene that belong to large phylogenetic groups not previously investigated with next generation technologies. The assembled and annotated transcriptomes are used for identifying low copy nuclear regions, suitable for sequencing.


2021 ◽  
Vol 8 ◽  
Author(s):  
Yunbang Zhang ◽  
Jian Gao ◽  
Yunhai Zhang ◽  
Yuanchao Zou ◽  
Xiaojuan Cao

Elongate loach (Leptobotia elongata) is endemic to middle and upper reaches of the Yangtze River in China. Due to overfishing and habitat destruction, this loach has become an endangered species. So far, lack of reliable genetic information and molecular markers has hindered the conservation and utilization of elongate loach resources. Therefore, we here performed an Illumina sequencing and de novo transcriptome assembly in elongate loach, and then developed polymorphic simple sequence repeat markers (SSRs). After assembly, 51,185 unigenes were obtained, with an average length of 1,496 bp. A total of 23,901 expressed sequence tag-simple sequence repeats (EST-SSRs) were identified, distributing in 14,422 unigenes, with a distribution frequency of 28.18%. Out of 16,885 designed EST-SSR primers, 150 primers (3 or 4 base repetition-dominated) were synthesized for polymorphic EST-SSR development. Then, 52 polymorphic EST-SSRs were identified, with polymorphism information contents (PIC) ranging from 0.03 to 0.88 (average 0.54). In conclusion, this was the first report of transcriptome sequencing of elongate loach. Meanwhile, we developed a set of polymorphic EST-SSRs for the loach. This study will provide an important basis, namely genetic information and polymorphic SSRs, for further population genetics and breeding studies of this endangered and economic loach in China.



Forests ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 411 ◽  
Author(s):  
Yu Ge ◽  
Lin Tan ◽  
Bin Wu ◽  
Tao Wang ◽  
Teng Zhang ◽  
...  

Avocado (Persea americana Mill.) could be considered as an important tropical and subtropical woody oil crop with high economic and nutritional value. Despite the importance of this species, genomic information is currently unavailable for avocado and closely related congeners. In this study, we generated more than 216 million clean reads from different avocado ecotypes using Illumina HiSeq high-throughput sequencing technology. The high-quality reads were assembled into 154,310 unigenes with an average length of 922 bp. A total of 55,558 simple sequence repeat (SSR) loci detected among the 43,270 SSR-containing unigene sequences were used to develop 74,580 expressed sequence tag (EST)-SSR markers. From these markers, a subset of 100 EST-SSR markers was randomly chosen to identify polymorphic EST-SSR markers in 28 avocado accessions. Sixteen EST-SSR markers with moderate to high polymorphism levels were detected, with polymorphism information contents ranging from 0.33 to 0.84 and averaging 0.63. These 16 polymorphic EST-SSRs could clearly and effectively distinguish the 28 avocado accessions. In summary, our study is the first presentation of transcriptome data of different avocado ecotypes and comprehensive study on the development and analysis of a set of EST-SSR markers in avocado. The application of next-generation sequencing techniques for SSR development is a potentially powerful tool for genetic studies.



Genes ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 378 ◽  
Author(s):  
Xiang Li ◽  
Meng Li ◽  
Lu Hou ◽  
Zhiyong Zhang ◽  
Xiaoming Pang ◽  
...  

Acer miaotaiense (P. C. Tsoong) is a rare and highly endangered plant in China. Because of the lack of genomic information and the limited number of available molecular markers, there are insufficient tools to determine the genetic diversity of this species. Here, 93,305 unigenes were obtained by multiple assembled contigs with a transcriptome sequencing program. Furthermore, 12,819 expressed sequence tag-derived simple sequence repeat (EST-SSR) markers were generated, 300 were randomly selected and synthesized, 19 primer pairs were identified as highly polymorphic (average number of alleles (Na) = 8, expected heterozygosity (He) = 0.635, polymorphism information content (PIC) = 0.604) and were further used for population genetic analysis. All 261 samples were grouped into two genetic clusters by UPGMA, a principal component analyses and a STRUCTURE analyses. A moderate level of genetic differentiation (genetic differentiation index (Fst) = 0.059–0.116, gene flow = 1.904–3.993) among the populations and the major genetic variance (81.01%) within populations were revealed by the AMOVA. Based on the results, scientific conservation strategies should be established using in situ and ex situ conservation strategies. The study provides useful genetic information for the protection of precious wild resources and for further research on the origin and evolution of this endangered plant and its related species.



2011 ◽  
Vol 12 (2) ◽  
pp. 333-343 ◽  
Author(s):  
DANIEL B. SLOAN ◽  
STEPHEN R. KELLER ◽  
ANDREA E. BERARDI ◽  
BRIAN J. SANDERSON ◽  
JOHN F. KARPOVICH ◽  
...  


2020 ◽  
Author(s):  
Liming Cai ◽  
Zhenxiang Xi ◽  
Emily Moriarty Lemmon ◽  
Alan R Lemmon ◽  
Austin Mast ◽  
...  

Abstract The genomic revolution offers renewed hope of resolving rapid radiations in the Tree of Life. The development of the multispecies coalescent (MSC) model and improved gene tree estimation methods can better accommodate gene tree heterogeneity caused by incomplete lineage sorting (ILS) and gene tree estimation error stemming from the short internal branches. However, the relative influence of these factors in species tree inference is not well understood. Using anchored hybrid enrichment, we generated a data set including 423 single-copy loci from 64 taxa representing 39 families to infer the species tree of the flowering plant order Malpighiales. This order includes nine of the top ten most unstable nodes in angiosperms, which have been hypothesized to arise from the rapid radiation during the Cretaceous. Here, we show that coalescent-based methods do not resolve the backbone of Malpighiales and concatenation methods yield inconsistent estimations, providing evidence that gene tree heterogeneity is high in this clade. Despite high levels of ILS and gene tree estimation error, our simulations demonstrate that these two factors alone are insufficient to explain the lack of resolution in this order. To explore this further, we examined triplet frequencies among empirical gene trees and discovered some of them deviated significantly from those attributed to ILS and estimation error, suggesting gene flow as an additional and previously unappreciated phenomenon promoting gene tree variation in Malpighiales. Finally, we applied a novel method to quantify the relative contribution of these three primary sources of gene tree heterogeneity and demonstrated that ILS, gene tree estimation error, and gene flow contributed to 10.0%, 34.8%, and 21.4% of the variation, respectively. Together, our results suggest that a perfect storm of factors likely influence this lack of resolution, and further indicate that recalcitrant phylogenetic relationships like the backbone of Malpighiales may be better represented as phylogenetic networks. Thus, reducing such groups solely to existing models that adhere strictly to bifurcating trees greatly oversimplifies reality, and obscures our ability to more clearly discern the process of evolution.



Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 1017
Author(s):  
Mohammed Bakkali ◽  
Rubén Martín-Blázquez ◽  
Mercedes Ruiz-Estévez ◽  
Manuel A. Garrido-Ramos

We sequenced the sporophyte transcriptome of Killarney fern (Vandenboschia speciosa (Willd.) G. Kunkel). In addition to being a rare endangered Macaronesian-European endemism, this species has a huge genome (10.52 Gb) as well as particular biological features and extreme ecological requirements. These characteristics, together with the systematic position of ferns among vascular plants, make it of high interest for evolutionary, conservation and functional genomics studies. The transcriptome was constructed de novo and contained 36,430 transcripts, of which 17,706 had valid BLAST hits. A total of 19,539 transcripts showed at least one of the 7362 GO terms assigned to the transcriptome, whereas 6547 transcripts showed at least one of the 1359 KEGG assigned terms. A prospective analysis of functional annotation results provided relevant insights on genes involved in important functions such as growth and development as well as physiological adaptations. In this context, a catalogue of genes involved in the genetic control of plant development, during the vegetative to reproductive transition, in stress response as well as genes coding for transcription factors is given. Altogether, this study provides a first step towards understanding the gene expression of a significant fern species and the in silico functional and comparative analyses reported here provide important data and insights for further comparative evolutionary studies in ferns and land plants in general.



2021 ◽  
Vol 9 (6) ◽  
pp. 1290
Author(s):  
Natalia Alvarez-Santullano ◽  
Pamela Villegas ◽  
Mario Sepúlveda Mardones ◽  
Roberto E. Durán ◽  
Raúl Donoso ◽  
...  

Burkholderia sensu lato (s.l.) species have a versatile metabolism. The aims of this review are the genomic reconstruction of the metabolic pathways involved in the synthesis of polyhydroxyalkanoates (PHAs) by Burkholderia s.l. genera, and the characterization of the PHA synthases and the pha genes organization. The reports of the PHA synthesis from different substrates by Burkholderia s.l. strains were reviewed. Genome-guided metabolic reconstruction involving the conversion of sugars and fatty acids into PHAs by 37 Burkholderia s.l. species was performed. Sugars are metabolized via the Entner–Doudoroff (ED), pentose-phosphate (PP), and lower Embden–Meyerhoff–Parnas (EMP) pathways, which produce reducing power through NAD(P)H synthesis and PHA precursors. Fatty acid substrates are metabolized via β-oxidation and de novo synthesis of fatty acids into PHAs. The analysis of 194 Burkholderia s.l. genomes revealed that all strains have the phaC, phaA, and phaB genes for PHA synthesis, wherein the phaC gene is generally present in ≥2 copies. PHA synthases were classified into four phylogenetic groups belonging to class I II and III PHA synthases and one outlier group. The reconstruction of PHAs synthesis revealed a high level of gene redundancy probably reflecting complex regulatory layers that provide fine tuning according to diverse substrates and physiological conditions.



2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Daniel Stribling ◽  
Peter L. Chang ◽  
Justin E. Dalton ◽  
Christopher A. Conow ◽  
Malcolm Rosenthal ◽  
...  

Abstract Objectives Arachnids have fascinating and unique biology, particularly for questions on sex differences and behavior, creating the potential for development of powerful emerging models in this group. Recent advances in genomic techniques have paved the way for a significant increase in the breadth of genomic studies in non-model organisms. One growing area of research is comparative transcriptomics. When phylogenetic relationships to model organisms are known, comparative genomic studies provide context for analysis of homologous genes and pathways. The goal of this study was to lay the groundwork for comparative transcriptomics of sex differences in the brain of wolf spiders, a non-model organism of the pyhlum Euarthropoda, by generating transcriptomes and analyzing gene expression. Data description To examine sex-differential gene expression, short read transcript sequencing and de novo transcriptome assembly were performed. Messenger RNA was isolated from brain tissue of male and female subadult and mature wolf spiders (Schizocosa ocreata). The raw data consist of sequences for the two different life stages in each sex. Computational analyses on these data include de novo transcriptome assembly and differential expression analyses. Sample-specific and combined transcriptomes, gene annotations, and differential expression results are described in this data note and are available from publicly-available databases.



2021 ◽  
Vol 22 (13) ◽  
pp. 6674
Author(s):  
Luisa Albarano ◽  
Valerio Zupo ◽  
Davide Caramiello ◽  
Maria Toscanesi ◽  
Marco Trifuoggi ◽  
...  

Sediment pollution is a major issue in coastal areas, potentially endangering human health and the marine environments. We investigated the short-term sublethal effects of sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) on the sea urchin Paracentrotus lividus for two months. Spiking occurred at concentrations below threshold limit values permitted by the law (TLVPAHs = 900 µg/L, TLVPCBs = 8 µg/L, Legislative Italian Decree 173/2016). A multi-endpoint approach was adopted, considering both adults (mortality, bioaccumulation and gonadal index) and embryos (embryotoxicity, genotoxicity and de novo transcriptome assembly). The slight concentrations of PAHs and PCBs added to the mesocosms were observed to readily compartmentalize in adults, resulting below the detection limits just one week after their addition. Reconstructed sediment and seawater, as negative controls, did not affect sea urchins. PAH- and PCB-spiked mesocosms were observed to impair P. lividus at various endpoints, including bioaccumulation and embryo development (mainly PAHs) and genotoxicity (PAHs and PCBs). In particular, genotoxicity tests revealed that PAHs and PCBs affected the development of P. lividus embryos deriving from exposed adults. Negative effects were also detected by generating a de novo transcriptome assembly and its annotation, as well as by real-time qPCR performed to identify genes differentially expressed in adults exposed to the two contaminants. The effects on sea urchins (both adults and embryos) at background concentrations of PAHs and PCBs below TLV suggest a need for further investigations on the impact of slight concentrations of such contaminants on marine biota.



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