Exploring Tomato Fruit Viromes through Transcriptome Data Analysis.

This study delves into the complex landscape of viral infections in tomatoes (Solanum lycopersicum) using available transcriptome data. We conducted a virome analysis, revealing 219 viral contigs linked to four distinct viruses: tomato chlorosis virus (ToCV), southern tomato virus (STV), tomato yellow leaf curl virus (TYLCV), and cucumber mosaic virus (CMV). Among these, ToCV predominated in contig count, followed by STV, TYLCV, and CMV. A notable finding was the prevalence of coinfections, emphasizing the concurrent presence of multiple viruses in tomato plants. Despite generally low viral levels in fruit transcriptomes, STV emerged as the primary virus based on viral read count. We delved deeper into viral abundance and the contributions of RNA segments to replication. While initially focused on studying the impact of sound treatment on tomato fruit transcriptomes, the unexpected viral presence underscores the importance of considering viruses in plant research. Geographical variations in virome communities hint at potential forensic applications. Phylogenetic analysis provided insights into viral origins and genetic diversity, enhancing our understanding of the Korean tomato virome. In conclusion, this study advances our knowledge of the tomato virome, stressing the need for robust pest control in greenhouse-grown tomatoes and offering insights into virus management and crop protection.

Investigating Variability in Viral Presence and Abundance across Soybean Seed Development Stages Using Transcriptome Analysis.

Plant transcriptomes offer a valuable resource for studying viral communities (viromes). In this study, we explore how plant transcriptome data can be applied to virome research. We analyzed 40 soybean transcriptomes across different growth stages and identified six viruses: broad bean wilt virus 2 (BBWV2), brassica yellow virus (BrYV), beet western yellow virus (BWYV), cucumber mosaic virus (CMV), milk vetch dwarf virus (MDV), and soybean mosaic virus (SMV). SMV was the predominant virus in both Glycine max (GM) and Glycine soja (GS) cultivars. Our analysis confirmed its abundance in both, while BBWV2 and CMV were more prevalent in GS than GM. The viral proportions varied across developmental stages, peaking in open flowers. Comparing viral abundance measured by viral reads and fragments per kilobase of transcript per million (FPKM) values revealed insights. SMV showed similar FPKM values in GM and GS, but BBWV2 and CMV displayed higher FPKM proportions in GS. Notably, the differences in viral abundance between GM and GS were generally insignificant based on the FPKM values across developmental stages, except for the apical bud stage in four GM cultivars. We also detected MDV, a multi-segmented virus, in two GM samples, with variable proportions of its segments. In conclusion, our study demonstrates the potential of plant transcriptomes for virome research, highlighting their strengths and limitations.

Outbreak of Rice Panicle Blast in Jeonbuk Province of Korea in 2021.

Rice panicle blast is one of the most serious diseases threatening stable rice production by causing severe damage to rice yields and quality. The disease is easy to occur under low air temperature and frequent heavy rainfall during the heading season of rice. In 2021, a rice panicle blast severely occurred in the Jeonbuk province of Korea. The incidence area of panicle blast accounted for 27.7% of the rice cultivation area of Jeonbuk province in 2021, which was 13.7-times higher than in 2019 and 2.6-times higher than in 2020. This study evaluated the incidence areas of rice panicle blast in each region of Jeonbuk province in 2021. The weather conditions during the heading season of rice, mainly cultivated rice cultivars, and the race diversity of the Jeonbuk isolates were also investigated. It will provide important information for the effective control of the rice panicle blast.

Phylogenetic and Phylodynamic Analyses of Soybean Mosaic Virus Using 305 Coat Protein Gene Sequences.

Soybean mosaic virus (SMV) of the family Potyviridae is the most devastating virus that infects soybean plants. In this study, we obtained 83 SMV coat protein (CP) sequences from seven provinces in Korea using RT-PCR and Sanger sequencing. Phylogenetic and haplotype analyses revealed eight groups of 83 SMV isolates and a network of 50 SMV haplotypes in Korea. The phylogenetic tree using 305 SMV CP sequences available worldwide revealed 12 clades that were further divided into two groups according to the plant hosts. Recombination rarely occurred in the CP sequences, while negative selection was dominant in the SMV CP sequences. Genetic diversity analyses revealed that plant species had a greater impact on the genetic diversity of SMV CP sequences than geographical origin or location. SMV isolates identified from Pinellia species in China showed the highest genetic diversity. Phylodynamic analysis showed that the SMV isolates between the two Pinellia species diverged in the year 1248. Since the divergence of the first SMV isolate from Glycine max in 1486, major clades for SMV isolates infecting Glycine species seem to have diverged from 1791 to 1886. Taken together, we provide a comprehensive overview of the genetic diversity and divergence of SMV CP sequences.

Evolution and Phylogeny of Soybean Mosaic Virus Based on 143 Complete Genomes.

Soybean mosaic virus (SMV) of the genus Potyvirus is an important virus in cultivated soybeans. Here, we obtained 7 SMV genomes from soybean germplasms using RNA sequencing and conducted a comprehensive evolutionary and phylogenetic study of 143 SMV genomes derived from 10 plant species and 12 countries. The phylogenetic tree we constructed using coding DNA sequences revealed the existence of nine clades of SMV isolates/strains. Recombination analysis revealed 76 recombinant events and 141 recombinants in total. Clades 1 and 3 contain the most common SMV pathotypes, including G1 through G7, which are distributed worldwide. Clade 2 includes several Chinese SMV pathotypes. The SMV isolates were further divided into two groups. The SMV isolates in the first group, including clades 8 and 9, were identified from Pinellia and Atractylodes species, whereas those in the second group (clades 1 through 7) were mostly found in cultivated soybeans. The SMV polyprotein undergoes positive selection, whereas most mature proteins, except for the P1 protein, undergo negative selection. The P1 protein of SMV isolates in group 1 may be highly correlated with host adaptation. This study provides strong evidence that recombination and plant hosts are powerful forces driving the genetic diversity of the SMV genome.

Metabolite Contents and Antioxidant Activities of Soybean (Glycine max (L.) Merrill) Seeds of Different Seed Coat Colors.

Seed coat color is one of the main agronomical traits that determine the chemical quality of soybean seeds and has been used as a parameter during cultivar development. In this study, seeds of yellow (n = 10), greenish-yellow (n = 5), and light-yellow (n = 4) soybean accessions were evaluated for their contents of total protein, total oil, total phenolic (TPC), and five prominent fatty acids including palmitic acid (PA), stearic acid (SA), oleic acid (OA), linoleic acid (LA), and linolenic acid (LLA), relative to a control cultivar, and the effect of seed coat color on each was investigated. Antioxidant activity was also evaluated using 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, Trolox equivalent antioxidant capacity (TEAC), and ferric reducing antioxidant power (FRAP). The results showed significant variations of metabolite contents and antioxidant activities between the soybeans. The average TPC, DPPH-radical scavenging activity, and FRAP were each in the order of greenish-yellow > yellow > light-yellow soybeans. In contrast, light-yellow soybeans contained a high level of OA and low levels of SA, LA, and LLA, each except LA differing significantly from yellow and greenish-yellow soybeans (p < 0.05). Our findings suggest that greenish-yellow and light-yellow soybeans could be good sources of antioxidants and high-quality soybean oil, respectively.

Soybean Viromes in the Republic of Korea Revealed by RT-PCR and Next-Generation Sequencing.

Soybean (Glycine max L.) is one of the most important crop plants in the Republic of Korea. Here, we conducted a soybean virome study. We harvested a total of 172 soybean leaf samples showing disease symptoms from major soybean-growing regions in the Republic of Korea. Individual samples were examined for virus infection by RT-PCR. Moreover, we generated eight libraries representing eight provinces by pooling samples and four libraries from single samples. RNA-seq followed by bioinformatics analyses revealed 10 different RNA viruses infecting soybean. The proportion of viral reads in each transcriptome ranged from 0.2 to 31.7%. Coinfection of different viruses in soybean plants was very common. There was a single dominant virus in each province, and this geographical difference might be related to the soybean seeds that transmit viruses. In this study, 32 viral genome sequences were assembled and successfully used to analyze the phylogenetic relationships and quasispecies nature of the identified RNA viruses. Moreover, RT-PCR with newly developed primers confirmed infection of the identified viruses in each library. Taken together, our soybean virome study provides a comprehensive overview of viruses infecting soybean in eight geographical regions in the Republic of Korea and four single soybean plants in detail.

Development of a transcranial direct current stimulation (tDCS) device based on polarity interchangeable electrodes.

BACKGROUND: Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that can help modulate cortical excitability by transmitting direct current (DC) between a pair of scalp electrodes. To date, most studies on tDCS have been relatively short-lived, and the DC stimulations only lasted a few minutes. Conventional tDCS devices usually have some problems such as needing a lot of patches and lead lines. OBJECTIVE: Since conventional tDCS devices are unsuitable for use in long-term stimulations, we developed a new tDCS which can easily be used by unskilled persons. METHODS: We developed a new tDCS device that does not have lead lines for tDCS electrodes and has a simple structure. RESULT: This device can achieve stimulation with polarity interchangeable DC without physically swapping the anode and cathode. The performance of the proposed device was verified through an experiment. CONCLUSION: The developed tDCS device can contribute to long-term research as it uses neuroelectric stimulation.

Sweet potato viromes in eight different geographical regions in Korea and two different cultivars.

The sweet potato in the family Convolvulaceae is a dicotyledonous perennial plant. Here, we conducted a comprehensive sweet potato virome study using 10 different libraries from eight regions in Korea and two different sweet potato cultivars by RNA-Sequencing. Comprehensive bioinformatics analyses revealed 10 different virus species infecting sweet potato. Moreover, we identified two novel viruses infecting sweet potato referred to as Sweet potato virus E (SPVE) in the genus Potyvirus and Sweet potato virus F (SPVF) in the genus Carlavirus. Of the identified viruses, Sweet potato feathery mottle virus (SPFMV) was the dominant virus followed by Sweet potato virus C (SPVC) and SPVE in Korea. We obtained a total of 30 viral genomes for eight viruses. Our phylogenetic analyses showed many potyvirus isolates are highly correlated with geographical regions. However, two isolates of SPFMV and a single isolate of Sweet potato virus G (SPVG) were genetically distant from other known isolates. The mutation rate was the highest in SPFMV followed by SPVC and SPVG. Two different sweet potato cultivars, Beni Haruka and Hogammi, were infected by seven and five viruses, respectively. Taken together, we provide a complete list of viruses infecting sweet potato in Korea and diagnostic methods.

Barley RNA viromes in six different geographical regions in Korea.

Barley is a kind of cereal grass belonging to the family Poaceae. To examine viruses infecting winter barley in Korea, we carried out a comprehensive study of barley RNA viromes using next-generation sequencing (NGS). A total of 110 barley leaf samples from 17 geographical locations were collected. NGS followed by extensive bioinformatics analyses revealed six different barley viromes: Barley yellow mosaic virus (BaYMV), Barley mild mosaic virus (BaMMV), Barley yellow dwarf virus (BYDV), Hordeum vulgare endornavirus (HvEV), and Barley virus G (BVG). BaYMV and HvEV were identified in all libraries, while other viruses were identified in some specific library. Based on the number of virus-associated reads, BaYMV was a dominant virus infecting winter barley in Korea causing yellow disease symptoms. We obtained nearly complete genomes of six BaYMV isolates and two BaMMV isolates. Phylogenetic analyses indicate that BaYMV and BaMMV were largely grouped based on geographical regions such as Asia and Europe. Single nucleotide polymorphisms analyses suggested that most BaYMV and BaMMV showed strong genetic variations; however, BaYMV isolate Jeonju and BaMMV isolate Gunsan exhibited a few and no SNPs, respectively, suggesting low level of genetic variation. Taken together, this is the first study of barley RNA viromes in Korea.

Identification of viral domains integrated into Arabidopsis proteome.

Horizontal gene transfer (HGT) contributes to the genome evolution of living organisms. In particular, several recent studies provide convincing data on the integration of viral sequences into diverse organisms. Here, we identified 101 viral domains integrated into the model plant Arabidopsis proteome. Functional analysis based on gene ontology (GO) terms indicates that viral domains in the Arabidopsis proteome were involved in various stress responses with binding functions. Protein interaction networks support the strong protein interactions of viral domains with other Arabidopsis proteins. A proteome-wide analysis gave a comprehensive evolutionary view of viral domains integrated into 41 plant proteomes, revealing the specific and conserved integration of viral domains into plant proteomes. Phylogenetic analyses revealed the possible HGT between viral domains and plant proteomes. Our results provide an overview of the integration of viral domains into plant proteomes and their possible functional roles associated with plant defense mechanisms.

Complete genome sequence of peanut virus C, a putative novel ilarvirus.

We determined the complete genome sequence of a putative novel ilarvirus, tentatively named "peanut virus C" (PVC), identified in peanut (Arachis hypogaea). The three segmented genomic RNA molecules of PVC were 3474 (RNA1), 2925 (RNA2), and 2160 (RNA3) nucleotides in length, with five predicted open reading frames containing conserved domains and motifs that are typical features of ilarviruses. The three genomic RNAs shared nucleotide sequence similarity (74% identity and 93% query coverage for RNA1, 75% identity and 85% query coverage for RNA2, and 72% identity and 70% query coverage for RNA3) with the most closely related ilarvirus, parietaria mottle virus. These results suggest that PVC is a novel member of the genus Ilarvirus in the family Bromoviridae.

Peach RNA viromes in six different peach cultivars.

Many recent studies have demonstrated that several known and unknown viruses infect many horticultural plants. However, the elucidation of a viral population and the understanding of the genetic complexity of viral genomes in a single plant are rarely reported. Here, we conducted metatranscriptome analyses using six different peach trees representing six individual peach cultivars. We identified six viruses including five viruses in the family Betaflexiviridae and a novel virus belonging to the family Tymoviridae as well as two viroids. The number of identified viruses and viroids in each transcriptome ranged from one to six. We obtained 18 complete or nearly complete genomes for six viruses and two viroids using transcriptome data. Furthermore, we analyzed single nucleotide variations for individual viral genomes. In addition, we analyzed the amount of viral RNA and copy number for identified viruses and viroids. Some viruses or viroids were commonly present in different cultivars; however, the list of infected viruses and viroids in each cultivar was different. Taken together, our study reveals the viral population in a single peach tree and a comprehensive overview for the diversities of viral communities in different peach cultivars.

De novo Genome Assembly and Single Nucleotide Variations for Soybean Mosaic Virus Using Soybean Seed Transcriptome Data.

Soybean is the most important legume crop in the world. Several diseases in soybean lead to serious yield losses in major soybean-producing countries. Moreover, soybean can be infected by diverse viruses. Recently, we carried out a large-scale screening to identify viruses infecting soybean using available soybean transcriptome data. Of the screened transcriptomes, a soybean transcriptome for soybean seed development analysis contains several virus-associated sequences. In this study, we identified five viruses, including soybean mosaic virus (SMV), infecting soybean by de novo transcriptome assembly followed by blast search. We assembled a nearly complete consensus genome sequence of SMV China using transcriptome data. Based on phylogenetic analysis, the consensus genome sequence of SMV China was closely related to SMV isolates from South Korea. We examined single nucleotide variations (SNVs) for SMVs in the soybean seed transcriptome revealing 780 SNVs, which were evenly distributed on the SMV genome. Four SNVs, C-U, U-C, A-G, and G-A, were frequently identified. This result demonstrated the quasispecies variation of the SMV genome. Taken together, this study carried out bioinformatics analyses to identify viruses using soybean transcriptome data. In addition, we demonstrated the application of soybean transcriptome data for virus genome assembly and SNV analysis.

Genome Sequence of Grapevine Virus K, a Novel Vitivirus Infecting Grapevine.

Here, we report the genome sequence of grapevine virus K (GVK), a novel single-stranded RNA virus identified from a transcriptome of grapevine. The genome of GVK is 7,476 nucleotides in length and encodes 5 open reading frames. GVK is a putative member of the genus Vitivirus in the family Betaflexiviridae.

Genome Sequence of Grapevine Virus T, a Novel Foveavirus Infecting Grapevine.

Here, we report the genome sequence of grapevine virus T (GVT), a novel single-stranded RNA virus identified from a transcriptome of grapevine. The genome of GVT is 8,701 nucleotides in length and encodes five open reading frames. GVT is a putative member of the genus Foveavirus in the family Betaflexiviridae.

Complete genome sequence of rice virus A, a new member of the family Tombusviridae.

An evaluation of the virus population in rice plants using next-generation sequencing technologies resulted in the discovery of a new RNA virus, tentatively named rice virus A (RVA). The complete RVA genome sequence was determined and analyzed, revealing a genome organization resembling that of viruses classified in the genera Aureusvirus, Tombusvirus and Zeavirus within the family Tombusviridae. With 4,832 nucleotides, the RVA genome may be the largest monopartite genome sequenced to date in the family Tombusviridae. The 453-amino acid RVA coat protein shares the highest identity with the gp3 protein of an unclassified carascovirus, SF1 (GenBank accession no. KF510027) isolated from San Francisco wastewater, rather than the coat protein of any known member of the family Tombusviridae. These novel characteristics represent a significant divergence from the genomes of viruses belonging to the sixteen existing genera of the family Tombusviridae, demonstrating that RVA is likely a new family member.

The pepper virome: natural co-infection of diverse viruses and their quasispecies.

BACKGROUND: The co-infection of diverse viruses in a host plant is common; however, little is known about viral populations and their quasispecies in the host. RESULTS: Here, we report the first pepper viromes that were co-infected by different types of viral genomes. The pepper viromes are dominated by geminivirus DNA-A followed by a novel carlavirus referred to as Pepper virus A. The two pepper cultivars share similar viral populations and replications. However, the quasispecies for double-stranded RNA virus and two satellite DNAs were heterogeneous and homogenous in susceptible and resistant cultivars, respectively, indicating the quasispecies of an individual virus depends on the host. CONCLUSIONS: Taken together, we provide the first evidence that the host plant resistant to viruses has an unrevealed antiviral system, affecting viral quasispecies, not replication.

Integrated analyses using RNA-Seq data reveal viral genomes, single nucleotide variations, the phylogenetic relationship, and recombination for Apple stem grooving virus.

BACKGROUND: Next-generation sequencing (NGS) provides many possibilities for plant virology research. In this study, we performed integrated analyses using plant transcriptome data for plant virus identification using Apple stem grooving virus (ASGV) as an exemplar virus. We used 15 publicly available transcriptome libraries from three different studies, two mRNA-Seq studies and a small RNA-Seq study. RESULTS: We de novo assembled nearly complete genomes of ASGV isolates Fuji and Cuiguan from apple and pear transcriptomes, respectively, and identified single nucleotide variations (SNVs) of ASGV within the transcriptomes. We demonstrated the application of NGS raw data to confirm viral infections in the plant transcriptomes. In addition, we compared the usability of two de novo assemblers, Trinity and Velvet, for virus identification and genome assembly. A phylogenetic tree revealed that ASGV and Citrus tatter leaf virus (CTLV) are the same virus, which was divided into two clades. Recombination analyses identified six recombination events from 21 viral genomes. CONCLUSIONS: Taken together, our in silico analyses using NGS data provide a successful application of plant transcriptomes to reveal extensive information associated with viral genome assembly, SNVs, phylogenetic relationships, and genetic recombination.

De novo transcriptome assembly of Sorghum bicolor variety Taejin.

Sorghum (Sorghum bicolor), also known as great millet, is one of the most popular cultivated grass species in the world. Sorghum is frequently consumed as food for humans and animals as well as used for ethanol production. In this study, we conducted de novo transcriptome assembly for sorghum variety Taejin by next-generation sequencing, obtaining 8.748 GB of raw data. The raw data in this study can be available in NCBI SRA database with accession number of SRX1715644. Using the Trinity program, we identified 222,161 transcripts from sorghum variety Taejin. We further predicted coding regions within the assembled transcripts by the TransDecoder program, resulting in a total of 148,531 proteins. We carried out BLASTP against the Swiss-Prot protein sequence database to annotate the functions of the identified proteins. To our knowledge, this is the first transcriptome data for a sorghum variety derived from Korea, and it can be usefully applied to the generation of genetic markers.