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September 22, 2019

A manganese superoxide dismutase (MnSOD) from red lip mullet, Liza haematocheila: Evaluation of molecular structure, immune response, and antioxidant function.

Manganese superoxide dismutase (MnSOD) is a nuclear-encoded antioxidant metalloenzyme. The main function of this enzyme is to dismutase the toxic superoxide anion (O2-) into less toxic hydrogen peroxide (H2O2) and oxygen (O2). Structural analysis of mullet MnSOD (MuMnSOD) was performed using different bioinformatics tools. Pairwise alignment revealed that the protein sequence matched to that derived from Larimichthys crocea with a 95.2% sequence identity. Phylogenetic tree analysis showed that the MuMnSOD was included in the category of teleosts. Multiple sequence alignment showed that a SOD Fe-N domain, SOD Fe-C domain, and Mn/Fe SOD signature were highly conserved among the other examined MnSOD orthologs. Quantitative real-time PCR showed that the highest MuMnSOD mRNA expression level was in blood cells. The highest expression level of MuMnSOD was observed in response to treatment with both Lactococcus garvieae and lipopolysaccharide (LPS) at 6?h post treatment in the head kidney and blood. Potential ROS-scavenging ability of the purified recombinant protein (rMuMnSOD) was examined by the xanthine oxidase assay (XOD assay). The optimum temperature and pH for XOD activity were found to be 25?°C and pH 7, respectively. Relative XOD activity was significantly increased with the dose of rMuMnSOD, revealing its dose dependency. Activity of rMuMnSOD was inhibited by potassium cyanide (KCN) and N-N’-diethyl-dithiocarbamate (DDC). Moreover, expression of MuMnSOD resulted in considerable growth retardation of both gram-positive and gram-negative bacteria. Results of the current study suggest that MuMnSOD acts as an antioxidant enzyme and participates in the immune response in mullet. Copyright © 2018 Elsevier Ltd. All rights reserved.

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September 22, 2019

Transcriptome characterization of moso bamboo (Phyllostachys edulis) seedlings in response to exogenous gibberellin applications.

Moso bamboo (Phyllostachys edulis) is a well-known bamboo species of high economic value in the textile industry due to its rapid growth. Phytohormones, which are master regulators of growth and development, serve as important endogenous signals. However, the mechanisms through which phytohormones regulate growth in moso bamboo remain unknown to date.Here, we reported that exogenous gibberellins (GA) applications resulted in a significantly increased internode length and lignin condensation. Transcriptome sequencing revealed that photosynthesis-related genes were enriched in the GA-repressed gene class, which was consistent with the decrease in leaf chlorophyll concentrations and the lower rate of photosynthesis following GA treatment. Exogenous GA applications on seedlings are relatively easy to perform, thus we used 4-week-old whole seedlings of bamboo for GA- treatment followed by high throughput sequencing. In this study, we identified 932 cis-nature antisense transcripts (cis-NATs), and 22,196 alternative splicing (AS) events in total. Among them, 42 cis-nature antisense transcripts (cis-NATs) and 442 AS events were differentially expressed upon exposure to exogenous GA3, suggesting that post-transcriptional regulation might be also involved in the GA3 response. Targets of differential expression of cis-NATs included genes involved in hormone receptor, photosynthesis and cell wall biogenesis. For example, LAC4 and its corresponding cis-NATs were GA3-induced, and may be involved in the accumulation of lignin, thus affecting cell wall composition.This study provides novel insights illustrating how GA alters post-transcriptional regulation and will shed light on the underlying mechanism of growth modulated by GA in moso bamboo.

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September 22, 2019

Fungal community shifts underpin declining mycelial production and turnover across a Pinus sylvestris chronosequence

Fungi play critical roles in ecosystem processes such as decomposition and nutrient cycling, but have also been highlighted as significant contributors to organic matter build-up in boreal forest soils. Ectomycorrhizal (ECM) mycelial biomass and necromass dynamics have recently been highlighted as essential for regulating build-up of soil organic matter. Understanding the extent to which shifts in mycelial community or growth trait composition cause changes in mycelial production and turnover over ecological gradients would aid a mechanistic understanding of these important processes at an ecosystem scale. Here, we test the hypotheses that shifting species and mycelial trait (exploration type) composition within the mycelial community underpin changes in biomass turnover with increasing forest age. We quantified mycelial turnover and assessed fungal community composition in a chronosequence of eight, 12- to 158-year-old, managed Pinus sylvestris forests. Turnover was estimated by determining mycelial biomass (ergosterol) in a sequence of ingrowth mesh bags and applying mathematical models. Fungal communities in the bags were identified using Pacific Biosciences sequencing of fungal ITS2 amplicons. To evaluate the accuracy of this method to represent all ECM fungi, community composition in bags was followed over time and compared with communities in soil. Mycelial communities changed with stand age, but we found no evidence that there were concurrent shifts in mycelial exploration types. Forest age and turnover were significantly correlated with ECM mycelial community composition and collectively explained 39.4% of total variation. The similarity between fungal communities in mesh bags and in soil was strongly forest age dependent, with communities in mesh bags diverging from soil communities in stands older than 60 years. However, in all stands, when bag incubation time exceeded 75 days, communities became more similar to soil communities. Synthesis. Our results support the idea that shifts in fungal community composition underpin the forest age-related decrease in mycelial turnover; however, since ingrowth mesh bags exclude some mycorrhizal species in older forests, it remains a possibility that turnover estimates were not reflecting the entire community. While we found no evidence that mycelial exploration types of fungi changed systematically with forest age, we suggest that other traits that relate to biomass turnover and necromass degradation require further study, as they may explain the extent to which ectomycorrhizal fungi regulate and contribute to soil organic matter accumulation.

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September 22, 2019

Construction of a draft reference transcripts of onion (Allium cepa) using long-read sequencing

To obtain intact and full-length RNA transcripts of onion (Allium cepa), long-read sequencing technology was first applied. Total RNAs extracted from four tissues; flowers, leaves, bulbs and roots, of red–purple and yellow-colored onions (A. cepa) were sequenced using long-read sequencing (RSII platform, P4-C2 chemistry). The 99,247 polished high-quality isoforms were produced by sequence correction processes of consensus calling, quality filtering, orientation verification, misread-nucleotide correction and dot-matrix view. The dot-matrix view was subsequently used to remove artificial inverted repeats (IRs), and resultantly 421 IRs were removed. The remaining 98,826 isoforms were condensed to 35,505 through the removal process of redundant isoforms. To assess the completeness of the 35,505 isoforms, the ratio of full-length isoforms, short-read mapping to the isoforms, and differentially expressed genes among the four tissues were analyzed along with the gene ontology across the tissues. As a result, the 35,505 isoforms were verified as a collection of isoforms with high completeness, and designated as draft reference transcripts (DRTs, ver 1.0) constructed by long-read sequencing.

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September 22, 2019

Bacterial diversity and community structure in Chongqing radish paocai brines revealed using PacBio single-molecule real-time sequencing technology.

Traditional Chongqing radish paocai fermented with aged brine is considered to have the most intense flavor and authentic taste. Eight ‘Yanzhi’ (red, RRPB group) and ‘Chunbulao’ (white, WRPB) radish paocai brine samples were collected from Chongqing peasant households, and the diversity and community structures of bacteria present in these brines were determined using PacBio single-molecule real-time sequencing of their full-length 16S rRNA genes.In total, 30 phyla, 218 genera, and 306 species were identified from the RRPB group, with 20 phyla, 261 genera, and 420 species present in the WRPB group. Obvious differences in bacterial profiles between the RRPB and WRPB groups were found, with the bacterial diversity of the WRPB group shown to be greater than that of the RRPB group. This study revealed several characteristics of the bacteria composition, including the predominance of heterofermentative lactic acid bacteria, the species diversity of genus Pseudomonas, and the presence of three opportunistic pathogenic species.This study provides detailed information on the bacterial diversity and community structure of Chongqing radish paocai brine samples, and suggests it may be necessary to analyze paocai brine for potential sources of bacterial contamination and take appropriate measures to exclude any pathogenic species. © 2018 Society of Chemical Industry.© 2018 Society of Chemical Industry.

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September 22, 2019

Abiotic stresses modulate landscape of poplar transcriptome via alternative splicing differential intron retention, and isoform ratio switching.

Abiotic stresses affect plant physiology, development, growth, and alter pre-mRNA splicing. Western poplar is a model woody tree and a potential bioenergy feedstock. To investigate the extent of stress-regulated alternative splicing (AS), we conducted an in-depth survey of leaf, root, and stem xylem transcriptomes under drought, salt, or temperature stress. Analysis of approximately one billion of genome-aligned RNA-Seq reads from tissue- or stress-specific libraries revealed over fifteen millions of novel splice junctions. Transcript models supported by both RNA-Seq and single molecule isoform sequencing (Iso-Seq) data revealed a broad array of novel stress- and/or tissue-specific isoforms. Analysis of Iso-Seq data also resulted in the discovery of 15,087 novel transcribed regions of which 164 show AS. Our findings demonstrate that abiotic stresses profoundly perturb transcript isoform profiles and trigger widespread intron retention (IR) events. Stress treatments often increased or decreased retention of specific introns – a phenomenon described here as differential intron retention (DIR). Many differentially retained introns were regulated in a stress- and/or tissue-specific manner. A subset of transcripts harboring super stress-responsive DIR events showed persisting fluctuations in the degree of IR across all treatments and tissue types. To investigate coordinated dynamics of intron-containing transcripts in the study we quantified absolute copy number of isoforms of two conserved transcription factors (TFs) using Droplet Digital PCR. This case study suggests that stress treatments can be associated with coordinated switches in relative ratios between fully spliced and intron-retaining isoforms and may play a role in adjusting transcriptome to abiotic stresses.

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September 22, 2019

Retention of seed trees fails to lifeboat ectomycorrhizal fungal diversity in harvested Scots pine forests.

Fennoscandian forestry has in the past decades changed from natural regeneration of forests towards replantation of clear-cuts, which negatively impacts ectomycorrhizal fungal (EMF) diversity. Retention of trees during harvesting enables EMF survival, and we therefore expected EMF communities to be more similar to those in old natural stands after forest regeneration using seed trees compared to full clear-cutting and replanting. We sequenced fungal internal transcribed spacer 2 (ITS2) amplicons to assess EMF communities in 10- to 60-year-old Scots pine stands regenerated either using seed trees or through replanting of clear-cuts with old natural stands as reference. We also investigated local EMF communities around retained old trees. We found that retention of seed trees failed to mitigate the impact of harvesting on EMF community composition and diversity. With increasing stand age, EMF communities became increasingly similar to those in old natural stands and permanently retained trees maintained EMF locally. From our observations, we conclude that EMF communities, at least common species, post-harvest are more influenced by environmental filtering, resulting from environmental changes induced by harvest, than by the continuity of trees. These results suggest that retention of intact forest patches is a more efficient way to conserve EMF diversity than retaining dispersed single trees.© FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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September 22, 2019

The microbiota of freshwater fish and freshwater niches contain omega-3 producing Shewanella species.

Approximately 30 years ago, it was discovered that free-living bacteria isolated from cold ocean depths could produce polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) (20:5n-3) or docosahexaenoic acid (DHA) (22:6n-3), two PUFA essential for human health. Numerous laboratories have also discovered that EPA- and/or DHA-producing bacteria, many of them members of the Shewanella genus, could be isolated from the intestinal tracts of omega-3 fatty acid-rich marine fish. If bacteria contribute omega-3 fatty acids to the host fish in general or if they assist some bacterial species in adaptation to cold, then cold freshwater fish or habitats should also harbor these producers. Thus, we undertook a study to see if these niches also contained omega-3 fatty acid producers. We were successful in isolating and characterizing unique EPA-producing strains of Shewanella from three strictly freshwater native fish species, i.e., lake whitefish (Coregonus clupeaformis), lean lake trout (Salvelinus namaycush), and walleye (Sander vitreus), and from two other freshwater nonnative fish, i.e., coho salmon (Oncorhynchus kisutch) and seeforellen brown trout (Salmo trutta). We were also able to isolate four unique free-living strains of EPA-producing Shewanella from freshwater habitats. Phylogenetic and phenotypic analyses suggest that one producer is clearly a member of the Shewanella morhuae species and another is sister to members of the marine PUFA-producing Shewanella baltica species. However, the remaining isolates have more ambiguous relationships, sharing a common ancestor with non-PUFA-producing Shewanella putrefaciens isolates rather than marine S. baltica isolates despite having a phenotype more consistent with S. baltica strains. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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September 22, 2019

Full-length transcriptome sequences and the identification of putative genes for flavonoid biosynthesis in safflower.

The flower of the safflower (Carthamus tinctorius L.) has been widely used in traditional Chinese medicine for the ability to improve cerebral blood flow. Flavonoids are the primary bioactive components in safflower, and their biosynthesis has attracted widespread interest. Previous studies mostly used second-generation sequencing platforms to survey the putative flavonoid biosynthesis genes. For a better understanding of transcription data and the putative genes involved in flavonoid biosynthesis in safflower, we carry our study.High-quality RNA was extracted from six types of safflower tissue. The RNAs of different tissues were mixed equally and used for multiple size-fractionated libraries (1-2, 2-3 and 3-6 k) library construction. Five cells were carried (2 cells for 1-2 and for 2-3 k libraries and 1 cell for 3-6 k libraries). 10.43Gb clean data and 38,302 de-redundant sequences were captured. 44 unique isoforms were annotated as encoding enzymes involved in flavonoid biosynthesis. The full length flavonoid genes were characterized and their evolutional relationship and expressional pattern were analyzed. They can be divided into eight families, with a large differences in the tissue expression. The temporal expressions under MeJA treatment were also measured, 9 genes are significantly up-regulated and 2 genes are significantly down-regulated. The genes involved in flavonoid synthesis in safflower were predicted in our study. Besides, the SSR and lncRNA are also analyzed in our study.Full-length transcriptome sequences were used in our study. The genes involved in flavonoid synthesis in safflower were predicted in our study. Combined the determination of flavonoids, CtC4H2, CtCHS3, CtCHI3, CtF3H3, CtF3H1 are mainly participated in MeJA promoting the synthesis of flavonoids. Our results also provide a valuable resource for further study on safflower.

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September 22, 2019

Comparative transcriptomic and physiological analyses of Medicago sativa L. indicates that multiple regulatory networks are activated during continuous ABA treatment.

Alfalfa is the most extensively cultivated forage legume worldwide. However, the molecular mechanisms underlying alfalfa responses to exogenous abscisic acid (ABA) are still unknown. In this study, the first global transcriptome profiles of alfalfa roots under ABA treatments for 1, 3 and 12 h (three biological replicates for each time point, including the control group) were constructed using a BGISEQ-500 sequencing platform. A total of 50,742 isoforms with a mean length of 2541 bp were generated, and 4944 differentially expressed isoforms (DEIs) were identified after ABA deposition. Metabolic analyses revealed that these DEIs were involved in plant hormone signal transduction, transcriptional regulation, antioxidative defense and pathogen immunity. Notably, several well characterized hormone signaling pathways, for example, the core ABA signaling pathway, was activated, while salicylic acid, jasmonate and ethylene signaling pathways were mainly suppressed by exogenous ABA. Moreover, the physiological work showed that catalase and peroxidase activity and glutathione and proline content were increased after ABA deposition, which is in accordance with the dynamic transcript profiles of the relevant genes in antioxidative defense system. These results indicate that ABA has the potential to improve abiotic stress tolerance, but that it may negatively regulate pathogen resistance in alfalfa.

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September 22, 2019

Single-molecule real-time transcript sequencing facilitates common wheat genome annotation and grain transcriptome research.

The large and complex hexaploid genome has greatly hindered genomics studies of common wheat (Triticum aestivum, AABBDD). Here, we investigated transcripts in common wheat developing caryopses using the emerging single-molecule real-time (SMRT) sequencing technology PacBio RSII, and assessed the resultant data for improving common wheat genome annotation and grain transcriptome research.We obtained 197,709 full-length non-chimeric (FLNC) reads, 74.6 % of which were estimated to carry complete open reading frame. A total of 91,881 high-quality FLNC reads were identified and mapped to 16,188 chromosomal loci, corresponding to 13,162 known genes and 3026 new genes not annotated previously. Although some FLNC reads could not be unambiguously mapped to the current draft genome sequence, many of them are likely useful for studying highly similar homoeologous or paralogous loci or for improving chromosomal contig assembly in further research. The 91,881 high-quality FLNC reads represented 22,768 unique transcripts, 9591 of which were newly discovered. We found 180 transcripts each spanning two or three previously annotated adjacent loci, suggesting that they should be merged to form correct gene models. Finally, our data facilitated the identification of 6030 genes differentially regulated during caryopsis development, and full-length transcripts for 72 transcribed gluten gene members that are important for the end-use quality control of common wheat.Our work demonstrated the value of PacBio transcript sequencing for improving common wheat genome annotation through uncovering the loci and full-length transcripts not discovered previously. The resource obtained may aid further structural genomics and grain transcriptome studies of common wheat.

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September 22, 2019

Accurate characterization of the IFITM locus using MiSeq and PacBio sequencing shows genetic variation in Galliformes.

Interferon inducible transmembrane (IFITM) proteins are effectors of the immune system widely characterized for their role in restricting infection by diverse enveloped and non-enveloped viruses. The chicken IFITM (chIFITM) genes are clustered on chromosome 5 and to date four genes have been annotated, namely chIFITM1, chIFITM3, chIFITM5 and chIFITM10. However, due to poor assembly of this locus in the Gallus Gallus v4 genome, accurate characterization has so far proven problematic. Recently, a new chicken reference genome assembly Gallus Gallus v5 was generated using Sanger, 454, Illumina and PacBio sequencing technologies identifying considerable differences in the chIFITM locus over the previous genome releases.We re-sequenced the locus using both Illumina MiSeq and PacBio RS II sequencing technologies and we mapped RNA-seq data from the European Nucleotide Archive (ENA) to this finalized chIFITM locus. Using SureSelect probes capture probes designed to the finalized chIFITM locus, we sequenced the locus of a different chicken breed, namely a White Leghorn, and a turkey.We confirmed the Gallus Gallus v5 consensus except for two insertions of 5 and 1 base pair within the chIFITM3 and B4GALNT4 genes, respectively, and a single base pair deletion within the B4GALNT4 gene. The pull down revealed a single amino acid substitution of A63V in the CIL domain of IFITM2 compared to Red Jungle fowl and 13, 13 and 11 differences between IFITM1, 2 and 3 of chickens and turkeys, respectively. RNA-seq shows chIFITM2 and chIFITM3 expression in numerous tissue types of different chicken breeds and avian cell lines, while the expression of the putative chIFITM1 is limited to the testis, caecum and ileum tissues.Locus resequencing using these capture probes and RNA-seq based expression analysis will allow the further characterization of genetic diversity within Galliformes.

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September 22, 2019

The dynamic landscape of fission yeast meiosis alternative-splice isoforms.

Alternative splicing increases the diversity of transcriptomes and proteomes in metazoans. The extent to which alternative splicing is active and functional in unicellular organisms is less understood. Here, we exploit a single-molecule long-read sequencing technique and develop an open-source software program called SpliceHunter to characterize the transcriptome in the meiosis of fission yeast. We reveal 14,353 alternative splicing events in 17,669 novel isoforms at different stages of meiosis, including antisense and read-through transcripts. Intron retention is the major type of alternative splicing, followed by alternate “intron in exon.” Seven hundred seventy novel transcription units are detected; 53 of the predicted proteins show homology in other species and form theoretical stable structures. We report the complexity of alternative splicing along isoforms, including 683 intra-molecularly co-associated intron pairs. We compare the dynamics of novel isoforms based on the number of supporting full-length reads with those of annotated isoforms and explore the translational capacity and quality of novel isoforms. The evaluation of these factors indicates that the majority of novel isoforms are unlikely to be both condition-specific and translatable but consistent with the possibility of biologically functional novel isoforms. Moreover, the co-option of these unusual transcripts into newly born genes seems likely. Together, the results of this study highlight the diversity and dynamics at the isoform level in the sexual development of fission yeast. © 2017 Kuang et al.; Published by Cold Spring Harbor Laboratory Press.

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September 22, 2019

Global analysis of epigenetic regulation of gene expression in response to drought stress in Sorghum.

Abiotic stresses including drought are major limiting factors of crop yields and cause significant crop losses. Acquisition of stress tolerance to abiotic stresses requires coordinated regulation of a multitude of biochemical and physiological changes, and most of these changes depend on alterations in gene expression. The goal of this work is to perform global analysis of differential regulation of gene expression and alternative splicing, and their relationship with chromatin landscape in drought sensitive and tolerant cultivars. our Iso-Seq study revealed transcriptome-wide full-length isoforms at an unprecedented scale with over 11000 novel splice isoforms. Additionally, we uncovered alternative polyadenylation sites of ~11000 expressed genes and many novel genes. Overall, Iso-Seq results greatly enhanced sorghum gene annotations that are not only useful in analyentified differentially expressed genes and splicing events that are correlated with tzing all our RNA-seq, ChIP-seq and ATAC-seq data but also serve as a great resource to the plant biology community. Our studies idhe drought-resistant phenotype. An association between alternative splicing and chromatin accessibility was also revealed. Several computational tools developed here (TAPIS and iDiffIR) have been made freely available to the research community in analyzing alternative splicing and differential alternative splicing.

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September 22, 2019

Transcriptome profiling using Illumina- and SMRT-based RNA-seq of hot pepper for in-depth understanding of genes involved in CMV infection.

Hot pepper (Capsicum annuum L.) is becoming an increasingly important vegetable crop in the world. Cucumber mosaic virus (CMV) is a destructive virus that can cause leaf distortion and fruit lesions, affecting pepper production. However, studies on the response to CMV infection in pepper at the transcriptional level are limited. In this study, the transcript profiles of pepper leaves after CMV infection were investigated using Illumina and single-molecule real-time (SMRT) RNA-sequencing (RNA-seq). A total of 2143 differentially expressed genes (DEGs) were identified at five different stages. Gene ontology (GO) and KEGG analysis revealed that these DEGs were involved in the response to stress, defense response and plant-pathogen interaction pathways. Among these DEGs, several key genes that consistently appeared in studies of plant-pathogen interactions had increased transcript abundance after inoculation, including chitinase, pathogenesis-related (PR) protein, TMV resistance protein, WRKY transcription factor and jasmonate ZIM-domain protein. Four of these DEGs were further validated by quantitative real-time RT-PCR (qRT-PCR). Furthermore, a total of 73, 597 alternative splicing (AS) events were identified in the pepper leaves after CMV infection, distributed in 12, 615 genes. The intron retention of WRKY33 (Capana09g001251) might be involved in the regulation of CMV infection. Taken together, our study provides a transcriptome-wide insight into the molecular basis of resistance to CMV infection in pepper leaves and potential candidate genes for improving resistance cultivars. Copyright © 2018 Elsevier B.V. All rights reserved.

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