scholarly journals Single-Molecule Long-Read Sequencing Reveals the Diversity of Full-Length Transcripts in Leaves of Gnetum (Gnetales)

2019 ◽  
Vol 20 (24) ◽  
pp. 6350 ◽  
Author(s):  
Nan Deng ◽  
Chen Hou ◽  
Fengfeng Ma ◽  
Caixia Liu ◽  
Yuxin Tian

The limitations of RNA sequencing make it difficult to accurately predict alternative splicing (AS) and alternative polyadenylation (APA) events and long non-coding RNAs (lncRNAs), all of which reveal transcriptomic diversity and the complexity of gene regulation. Gnetum, a genus with ambiguous phylogenetic placement in seed plants, has a distinct stomatal structure and photosynthetic characteristics. In this study, a full-length transcriptome of Gnetum luofuense leaves at different developmental stages was sequenced with the latest PacBio Sequel platform. After correction by short reads generated by Illumina RNA-Seq, 80,496 full-length transcripts were obtained, of which 5269 reads were identified as isoforms of novel genes. Additionally, 1660 lncRNAs and 12,998 AS events were detected. In total, 5647 genes in the G. luofuense leaves had APA featured by at least one poly(A) site. Moreover, 67 and 30 genes from the bHLH gene family, which play an important role in stomatal development and photosynthesis, were identified from the G. luofuense genome and leaf transcripts, respectively. This leaf transcriptome supplements the reference genome of G. luofuense, and the AS events and lncRNAs detected provide valuable resources for future studies of investigating low photosynthetic capacity of Gnetum.

Author(s):  
Chengcai Zhang ◽  
Huadong Ren ◽  
Xiaohua Yao ◽  
Kailiang Wang ◽  
Jun Chang

Abstract Pecan is rich in bioactive components such as fatty acids and flavonoids and is an important nut type worldwide. Therefore, the molecular mechanisms of phytochemical biosynthesis in pecan are a focus of research. Recently, a draft genome and several transcriptomes have been published. However, the full-length mRNA transcripts remain unclear, and the regulatory mechanisms behind the quality components biosynthesis and accumulation have not been fully investigated. In this study, single-molecule long read sequencing technology was used to obtain full-length transcripts of pecan kernels. In total, 37 504 isoforms of 16 702 genes were mapped to the reference genome. The numbers of known isoforms, new isoforms, and novel isoforms were 9013 (24.03%), 26 080 (69.54%), and 2411 (6.51%), respectively. Over 80% of the transcripts (30 751, 81.99%) had functional annotations. A total of 15 465 alternative splicing (AS) events and 65 761 alternative polyadenylation events were detected; wherein, the retained intron was the predominant type (5652, 36.55%) of AS. Furthermore, 1894 long non-coding RNAs and 1643 transcription factors were predicted using bioinformatics methods. Finally, the structural genes associated with fatty acid (FA) and flavonoid biosynthesis were characterized. A high frequency of AS accuracy (70.31%) was observed in FA synthesis-associated genes. The present study provides a full-length transcriptome dataset of pecan kernels, which will significantly enhance the understanding of the regulatory basis of phytochemical biosynthesis during pecan kernel maturation.


Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 866
Author(s):  
Lei Kan ◽  
Qicong Liao ◽  
Zhiyao Su ◽  
Yushan Tan ◽  
Shuyu Wang ◽  
...  

Madhuca pasquieri (Dubard) Lam. is a tree on the International Union for Conservation of Nature Red List and a national key protected wild plant (II) of China, known for its seed oil and timber. However, lacking of genomic and transcriptome data for this species hampers study of its reproduction, utilization, and conservation. Here, single-molecule long-read sequencing (PacBio) and next-generation sequencing (Illumina) were combined to obtain the transcriptome from five developmental stages of M. pasquieri. Overall, 25,339 transcript isoforms were detected by PacBio, including 24,492 coding sequences (CDSs), 9440 simple sequence repeats (SSRs), 149 long non-coding RNAs (lncRNAs), and 182 alternative splicing (AS) events, a majority was retained intron (RI). A further 1058 transcripts were identified as transcriptional factors (TFs) from 51 TF families. PacBio recovered more full-length transcript isoforms with a longer length, and a higher expression level, whereas larger number of transcripts (124,405) was captured in de novo from Illumina. Using Nr, Swissprot, KOG, and KEGG databases, 24,405 transcripts (96.31%) were annotated by PacBio. Functional annotation revealed a role for the auxin, abscisic acid, gibberellin, and cytokinine metabolic pathways in seed germination and post-germination. These findings support further studies on seed germination mechanism and genome of M. pasquieri, and better protection of this endangered species.


2020 ◽  
Author(s):  
Yanping Long ◽  
Zhijian Liu ◽  
Jinbu Jia ◽  
Weipeng Mo ◽  
Liang Fang ◽  
...  

AbstractThe broad application of large-scale single-cell RNA profiling in plants has been restricted by the prerequisite of protoplasting. We recently found that the Arabidopsis nucleus contains abundant polyadenylated mRNAs, many of which are incompletely spliced. To capture the isoform information, we combined 10x Genomics and Nanopore long-read sequencing to develop a protoplasting-free full-length single-nucleus RNA profiling method in plants. Our results demonstrated using Arabidopsis root that nuclear mRNAs faithfully retain cell identity information, and single-molecule full-length RNA sequencing could further improve cell type identification by revealing splicing status and alternative polyadenylation at single-cell level.


2020 ◽  
Author(s):  
Tao Wang ◽  
Feng Yang ◽  
Qiaosheng Guo ◽  
Qingjun Zou ◽  
Wenyan Zhang ◽  
...  

Abstract Background: The inflorescence of Chrysanthemum morifolium cv. ‘Hangju’ has been widely used in China due to its antioxidant and anti-inflammatory properties. The biosynthesis and regulation of flavonoids, a group of bioactive components, in C. morifolium are poorly understood. Transcriptome sequencing is an effective method for obtaining transcript information. Therefore, single-molecule real-time (SMRT) sequencing was performed to obtain the full-length genes involved in flavonoid biosynthesis and regulation in C. morifolium.Results: High-quality RNA was extracted from the inflorescence of C. morifolium at different developmental stages and used to construct two libraries (0-5 kb and 4.5-10 kb) for sequencing. Finally, 125,532 non-redundant isoforms with a mean length of 2,009 bp were obtained. Of these, 2,083 transcripts were annotated to pathways related to flavonoid biosynthesis, and 56 isoforms were annotated as CHS, CHI, F3H, F3’H, FNS Ⅱ, FLS, DFR and ANS genes. Based on gene expression levels at different stages, we predicted the major genes involved in flavonoid biosynthesis. By phylogenetic analysis, we found two candidate MYB transcription factors (CmMYBF1 and CmMYBF2) activating flavonol biosynthesis.Conclusions: Based on the full-length transcriptomic data and further quantitative analysis, the major genes involved in flavonoid biosynthesis and regulation in C. morifolium were predicted in our study. The results provide a valuable theoretical basis for the introduction and cultivation of C. morifolium cv. ‘Hangju’.


2020 ◽  
Vol 21 (9) ◽  
pp. 3288
Author(s):  
Yawei Wu ◽  
Juan Xu ◽  
Xiumei Han ◽  
Guang Qiao ◽  
Kun Yang ◽  
...  

To gain more valuable genomic information about betalain biosynthesis, the full-length transcriptome of pitaya pulp from ‘Zihonglong’ (red pulp) and ‘Jinghonglong’ (white pulp) in four fruit developmental stages was analyzed using Single-Molecule Real-Time (SMRT) sequencing corrected by Illumina RNA-sequence (Illumina RNA-Seq). A total of 65,317 and 91,638 genes were identified in ‘Zihonglong’ and ‘Jinghonglong’, respectively. A total of 11,377 and 15,551 genes with more than two isoforms were investigated from ‘Zihonglong’ and ‘Jinghonglong’, respectively. In total, 156,955 genes were acquired after elimination of redundancy, of which, 120,604 genes (79.63%) were annotated, and 30,875 (20.37%) sequences without hits to reference database were probably novel genes in pitaya. A total of 31,169 and 53,024 simple sequence repeats (SSRs) were uncovered from the genes of ‘Zihonglong’ and ‘Jinghonglong’, and 11,650 long non-coding RNAs (lncRNAs) in ‘Zihonglong’ and 11,113 lncRNAs in ‘Jinghonglong’ were obtained herein. qRT-PCR was conducted on ten candidate genes, the expression level of six novel genes were consistent with the Fragments Per Kilobase of transcript per Million mapped reads (FPKM) values. In conclusion, we firstly undertook SMRT sequencing of the full-length transcriptome of pitaya, and the valuable resource that was acquired through this sequencing facilitated the identification of additional betalain-related genes. Notably, a list of novel putative genes related to the synthesis of betalain in pitaya fruits was assembled. This may provide new insights into betalain synthesis in pitaya.


2019 ◽  
Author(s):  
Yawei Wu ◽  
Juan Xu ◽  
Xiumei Han ◽  
Guang Qiao ◽  
Kun yang ◽  
...  

Abstract Background: In order to gain more valuable genomic information involved in betalain biosynthesis, the full-length transcriptome of pitaya was analyzed using Single-Molecule Real-Time (SMRT) sequencing corrected by RNA-seq in the present study. Two pitaya cultivars, ‘Zihonglong’ (red pulp) and ‘Jinghonglong’ (white pulp) were selected to analyze betalain transcriptome in four fruit developmental stages. Results: A total of 65,317 and 91,638 genes coding proteins were identified in ‘Zihonglong’ and ‘Jinghonglong’, respectively. A total of 11,377 and 15,551 genes with more than two isoforms were investigated from ‘Zihonglong’ and ‘Jinghonglong’, respectively. Also, 156,955 genes were acquired after elimination of redundancy , of which, 120,604 genes (79.63%) were annotated, and 30,875 (20.37%) sequences without hits to reference database were probably novel genes in pitaya. Totally, 31,169 and 53,024 SSRs were uncovered from the genes of ‘Zihonglong’ and ‘Jinghonglong’, and 11,650 lncRNAs in ‘Zihonglong’ and 11,113 lncRNAs in ‘Jinghonglong’ were obtained herein. Further, 104 genes involved in betalain metabolism were identified, and HpCYP76AD4 and HpDODA probably responded to betalains biosynthesis. Conclusions: Conclusively, this is the first study to perform SMRT sequencing of the full-length transcriptome of pitaya, which provides a useful genomic clue for exploring the structure and function of genes in pitaya, particularly for betalain biosynthesis.


2019 ◽  
Vol 14 (7) ◽  
pp. 566-573 ◽  
Author(s):  
Yubang Gao ◽  
Feihu Xi ◽  
Hangxiao zhang ◽  
Xuqing Liu ◽  
Huiyuan Wang ◽  
...  

Background: The advent of the Single-Molecule Real-time (SMRT) Isoform Sequencing (Iso-Seq) has paved the way to obtain longer full-length transcripts. This method was found to be much superior in identifying full-length splice variants and other post-transcriptional events as compared to the Next Generation Sequencing (NGS)-based short read sequencing (RNA-Seq). Several different bioinformatics tools to analyze the Iso-Seq data have been developed and some of them are still being refined to address different aspects of transcriptome complexity. However, a comprehensive summary of the available tools and their utility is still lacking. Objective: Here, we summarized the existing Iso-Seq analysis tools and presented an integrated bioinformatics pipeline for Iso-Seq analysis, which overcomes the limitations of NGS and generates long contiguous Full-Length Non-Chimeric (FLNC) reads for the analysis of posttranscriptional events. Results: In this review, we summarized recent applications of Iso-Seq in plants, which include improved genome annotations, identification of novel genes and lncRNAs, identification of fulllength splice isoforms, detection of novel Alternative Splicing (AS) and Alternative Polyadenylation (APA) events. In addition, we also discussed the bioinformatics pipeline for comprehensive Iso-Seq data analysis, including how to reduce the error rate in the reads and how to identify and quantify post-transcriptional events. Furthermore, the visualization approach of Iso-Seq was discussed as well. Finally, we discussed methods to combine Iso-Seq data with RNA-Seq for transcriptome quantification. Conclusion: Overall, this review demonstrates that the Iso-Seq is pivotal for analyzing transcriptome complexity and this new method offers unprecedented opportunities to comprehensively understand transcripts diversity.


2021 ◽  
Vol 12 ◽  
Author(s):  
Tianpeng Chang ◽  
Bingxing An ◽  
Mang Liang ◽  
Xinghai Duan ◽  
Lili Du ◽  
...  

Cattle (Bos taurus) is one of the most widely distributed livestock species in the world, and provides us with high-quality milk and meat which have a huge impact on the quality of human life. Therefore, accurate and complete transcriptome and genome annotation are of great value to the research of cattle breeding. In this study, we used error-corrected PacBio single-molecule real-time (SMRT) data to perform whole-transcriptome profiling in cattle. Then, 22.5 Gb of subreads was generated, including 381,423 circular consensus sequences (CCSs), among which 276,295 full-length non-chimeric (FLNC) sequences were identified. After correction by Illumina short reads, we obtained 22,353 error-corrected isoforms. A total of 305 alternative splicing (AS) events and 3,795 alternative polyadenylation (APA) sites were detected by transcriptome structural analysis. Furthermore, we identified 457 novel genes, 120 putative transcription factors (TFs), and 569 novel long non-coding RNAs (lncRNAs). Taken together, this research improves our understanding and provides new insights into the complexity of full-length transcripts in cattle.


2019 ◽  
Author(s):  
Dafu Chen ◽  
Yu Du ◽  
Xiaoxue Fan ◽  
Zhiwei Zhu ◽  
Haibin Jiang ◽  
...  

AbstractAscosphaera apis is a widespread fungal pathogen of honeybee larvae that results in chalkbrood disease, leading to heavy losses for the beekeeping industry in China and many other countries. This work was aimed at generating a full-length transcriptome of A. apis using PacBio single-molecule real-time (SMRT) sequencing. Here, more than 23.97 Gb of clean reads was generated from long-read sequencing of A. apis mecylia, including 464,043 circular consensus sequences (CCS) and 394,142 full-length non-chimeric (FLNC) reads. In total, we identified 174,095 high-confidence transcripts covering 5141 known genes with an average length of 2728 bp. We also discovered 2405 genic loci and 11,623 isoforms that have not been annotated yet within the current reference genome. Additionally, 16,049, 10,682, 4520 and 7253 of the discovered transcripts have annotations in the Non-redundant protein (Nr), Clusters of Eukaryotic Orthologous Groups (KOG), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Moreover, 1205 long non-coding RNAs (lncRNAs) were identified, which have less exons, shorter exon and intron lengths, shorter transcript lengths, lower GC percent, lower expression levels, and fewer alternative splicing (AS) evens, compared with protein-coding transcripts. A total of 253 members from 17 transcription factor (TF) families were identified from our transcript datasets. Finally, the expression of A. apis isoforms was validated using a molecular approach. Overall, this is the first report of a full-length transcriptome of entomogenous fungi including A. apis. Our data offer a comprehensive set of reference transcripts and hence contributes to improving the genome annotation and transcriptomic study of A. apis.


2019 ◽  
Author(s):  
Tao Wang ◽  
Feng Yang ◽  
Qiaosheng Guo ◽  
Qingjun Zou ◽  
Wenyan Zhang ◽  
...  

Abstract Background: The inflorescence of Chrysanthemum morifolium cv. ‘Hangju’ has been widely used in China due to its antioxidant and anti-inflammatory properties. The biosynthesis and regulation of flavonoids, a group of bioactive components, in C. morifolium are poorly understood. Transcriptome sequencing is an effective method for obtaining transcript information. Therefore, single-molecule real-time (SMRT) sequencing was performed to obtain the full-length genes involved in flavonoid biosynthesis and regulation in C. morifolium. Results: High-quality RNA was extracted from the inflorescence of C. morifolium at different developmental stages and used to construct two libraries (0-5 kb and 4.5-10 kb) for sequencing. Finally, 125,532 non-redundant isoforms with a mean length of 2,009 bp were obtained. Of these, 2,083 transcripts were annotated to pathways related to flavonoid biosynthesis, and 56 isoforms were annotated as CHS, CHI, F3H, F3’H, FNS Ⅱ, FLS, DFR and ANS genes. Based on gene expression levels at different stages, we predicted the major genes involved in flavonoid biosynthesis. By phylogenetic analysis, we found two candidate MYB transcription factors (CmMYBF1 and CmMYBF2) activating flavonol biosynthesis. Conclusions: Based on the full-length transcriptomic data and further quantitative analysis, the major genes involved in flavonoid biosynthesis and regulation in C. morifolium were predicted in our study. The results provide a valuable theoretical basis for the introduction and cultivation of C. morifolium cv. ‘Hangju’.


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