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Antiviral RNA interference inhibits virus vertical transmission in plants.

Known for over a century, seed transmission of plant viruses promotes trans-continental virus dissemination and provides the source of infection to trigger devastating disease epidemics in crops. However, it remains unknown whether there is a genetically defined immune pathway to suppress virus vertical transmission in plants. Here, we demonstrate potent immunosuppression of cucumber mosaic virus (CMV) seed transmission in its natural host Arabidopsis thaliana by antiviral RNA interference (RNAi) pathway. Immunofluorescence microscopy reveals predominant embryo infection at four stages of embryo development. We show that antiviral RNAi confers resistance to seed infection with different genetic requirements and drastically enhanced potency compared with the inhibition of systemic infection of whole plants. Moreover, we detect efficient seed transmission of a mutant CMV lacking its RNAi suppressor gene in mutant plants defective in antiviral RNAi, providing further support for the immunosuppression of seed transmission by antiviral RNAi.

Plant Diseases

A chromosome-scale assembly for the genome of southern corn rootworm, Diabrotica undecimpunctata.

Diabrotica undecimpunctata ssp. howardi, the southern corn rootworm or eastern 12-spotted cucumber beetle, is a generalist insect herbivore that causes damage and yield loss to several crops in North America including maize. Unresolved phylogenetic relationships within and among D. undecimpunctata subspecies are impacting current quarantine policies. We report the chromosome-level haploid genome assembly, icDiaUnde3, constructed using HiFi and Hi-C read data from a single male D. undecimpunctata collected and identified as subspecies howardi based on geographic location and morphology. The primary 1.74 Gbp assembly is scaffolded into 11 chromosome-length scaffolds representing 9 autosomes, a single X chromosome and a supernumerary (B) chromosome (scaffold N50 = 162.8 Mb and L50 = 5). Ab initio and evidence-based structural reference sequence (RefSeq) annotations predicted 18,959 protein-coding genes, in which 99.2% of the 1,367 Benchmark Universal Single-Copy Orthologs from Insecta were complete. Repeat elements occupy 1.26 Gbp (72.33%) of the icDiaUnde3 assembly, with nearly 36% predicted to be retroelements. Alignment of whole chromosomes from icDiaUnde3 with those previously assembled from Diabrotica spp. predicted 2 and 6 autosomal inversions with D. balteata and D. virgifera virgifera, respectively. The mitochondrial genome had an annotated gene order and orientation conserved among beetles. The icDiaUnde3 reference genome assembly is a vital resource for taxonomic, comparative, and functional studies to enhance sustainable crop production.

agriculture

Prevalence, Species Diversity, and Molecular Characterization of Viruses Infecting Phlox (Phlox paniculata) from Botanical Gardens in Russia.

Phlox (Phlox spp., Polemoniaceae) are herbaceous ornamental plants that are cultivated around the world for their fascinating flowering. P. paniculata cultivar collections at the Tsitsin Main Botanical Garden and the Botanical Garden of Lomonosov Moscow State University (both in Moscow, Russia) were surveyed for virus diseases using high-throughput sequencing and RT-PCR. Twenty-seven plants with virus-like symptoms on the leaves were selected for analysis. Alfalfa mosaic virus (AMV), Arabis mosaic virus (ArMV), ArMV satellite RNA (satRNA), beet ringspot nepovirus (BRSV), BRSV satRNA, cucumber mosaic virus (CMV), Spiranthes mosaic virus 3 (SpiMV3), tobacco streak virus (TSV), and tobacco rattle virus (TRV) were identified. AMV and TSV were the most common viruses found in 22 and 25 out of the 27 samples tested, respectively. ArMV satRNA was detected in phlox for the first time, adding to the list of viruses infecting this crop. The nearly complete genomes of the detected viruses and satRNAs were assembled and characterized. The CMV and TRV genome sequences from phlox were first deposited in GenBank. Only RNA1 was detected in the TRV-infected 'Fligelleutenant Bolke' cultivar plant, suggesting that the so-called non-multiplying infection has been found for the first time in a plant species other than solanaceae.

Arabis mosaic virus

Host Range and Chemical Control of Cercospora citrullina, the Causal Agent of Watermelon Spot Disease.

This study systematically evaluated cultivation requirements, host range, and chemical control options for Cercospora citrullina causing watermelon spot disease. Among 11 chemically defined media tested, corn meal agar medium supported optimal mycelial growth of C. citrullina, with an average radial growth rate of 56.72 ± 1.45 mm under controlled conditions (25°C, darkness). Host range determination via artificial inoculation of 19 plant species confirmed that the host range of the strain UNL090101 is limited to the Cucurbitaceae species tested, with watermelon (Citrullus lanatus) exhibiting the highest susceptibility, followed by melon (Cucumis melo) and cucumber (Cucumis sativus). Fungicide screening of 17 commercial formulations identified 40% iminoctadine tris (albesilate) WP (EC50 = 2.82 μg·liter-1) and 64% mancozeb + 8% cymoxanil (WS) (EC50 = 48.75 μg·liter-1) as the most effective treatments, achieving control efficacies of 74.47 and 58.62%, respectively. These findings provide actionable guidelines for optimizing crop rotation, intercropping strategies, and fungicide selection in watermelon production systems.

Cercospora citrullina

The coding-complete genome sequence of Arabidopsis latent virus 1 from Iraq.

Here, we report the coding-complete genome sequence of Arabidopsis latent virus 1 (ArLV1; Comovirus arabidopsis) from Iraq. The virus was identified by metatranscriptomic sequencing of asymptomatic cucumber (Cucumis sativus) leaves harboring thrips collected from commercial greenhouses. The bipartite genome comprises RNA1 (5,553 nt) and RNA2 (3,582 nt).

Arabidopsis latent virus 1

Proteome analysis provides insights into sex differences in Holothuria Scabra.

Sex-determining mechanism is still ambiguous for sea cucumber Holothuria scabra which only manifests gonochorism in gonad. In this study, proteomic analysis was employed to delineate sex-related proteins and genes in gonads of H. scabra, subsequently validated through Quantitative real-time polymerase chain reaction (qRT-PCR). A total of 5,313 proteins were identified via proteome sequencing. Among these, 817 proteins exhibited expression in both the ovary and testis, with 445 proteins displaying up-regulation and 372 proteins showing down-regulation (ovary vs testis). Furthermore, 136 and 69 proteins were identified as ovary-specific and testis-specific Differentially Abundant Proteins (DAPs), respectively. And 9 DAP coding genes which play crucial role in ovary and testis were verified by qRT-PCR. Notably, 24 ovary-bias proteins enriched in ribosome pathway strongly indicated the crucial role of ribosome in ovary. This study serves to furnish novel evidence pertaining to sex differences in H. scabra.

Animals

Diverse RNA viruses discovered in multiple seagrass species.

Seagrasses are marine angiosperms that form highly productive and diverse ecosystems. These ecosystems, however, are declining worldwide. Plant-associated microbes affect critical functions like nutrient uptake and pathogen resistance, which has led to an interest in the seagrass microbiome. However, despite their significant role in plant ecology, viruses have only recently garnered attention in seagrass species. In this study, we produced original data and mined publicly available transcriptomes to advance our understanding of RNA viral diversity in Zostera marina, Zostera muelleri, Zostera japonica, and Cymodocea nodosa. In Z. marina, we present evidence for additional Zostera marina amalgavirus 1 and 2 genotypes, and a complete genome for an alphaendornavirus previously evidenced by an RNA-dependent RNA polymerase gene fragment. In Z. muelleri, we present evidence for a second complete alphaendornavirus and near complete furovirus. Both are novel, and, to the best of our knowledge, this marks the first report of a furovirus infection naturally occurring outside of cereal grasses. In Z. japonica, we discovered genome fragments that belong to a novel strain of cucumber mosaic virus, a prolific pathogen that depends largely on aphid vectoring for host-to-host transmission. Lastly, in C. nodosa, we discovered two contigs that belong to a novel virus in the family Betaflexiviridae. These findings expand our knowledge of viral diversity in seagrasses and provide insight into seagrass viral ecology.

RNA Viruses

Hybridization capture increases on-target nanopore sequencing of plant RNA tobamovirus- derived cDNA libraries.

High-throughput sequencing (HTS) can support plant virus surveillance, but host nucleic acids often reduce on-target read recovery. We evaluated a targeted hybridization-capture workflow in which barcoded double-stranded cDNA (ds-cDNA) libraries generated from plant RNA extracts spiked with lyophilized tobamovirus-positive controls were enriched before Oxford Nanopore sequencing. Biotinylated probes targeted conserved regions of cucumber green mottle mosaic virus (CGMMV), species Tobamovirus viridimaculae; pepper mild mottle virus (PMMoV), species Tobamovirus capsici; and tobacco mosaic virus (TMV), species Tobamovirus tabaci. Across four pairs per virus, relative target-read abundance increased after capture from 0.76 ± 0.33% to 37.62 ± 15.72% for CGMMV, 8.16 ± 3.86% to 24.68 ± 12.34% for PMMoV, and 15.62 ± 10.40% to 36.83 ± 30.33% for TMV. Exact two-sided Wilcoxon signed-rank tests yielded P = 0.125 for each virus; with four nonzero differences in a common direction, this was the minimum attainable two-sided P value. Genome-coverage breadth was maintained. Retrospective duplex qPCR supported an increased virus-to-18S ratio for CGMMV, showed a variable PMMoV response, and showed a decreased virus-to-18S ratio for TMV because the 18S signal shifted earlier by as much as or more than the TMV signal. The findings provide proof-of-concept evidence for target-dependent library enrichment but do not establish analytical sensitivity, diagnostic performance, or field validity. Validation with naturally infected, low-titer, and mixed-infection samples and comparison with simpler targeted workflows are required.

biosecurity

Tobamoviruses: Advances in Molecular Biology, Host Interactions and Integrated Disease Management.

Tobamoviruses (viruses in the genus Tobamovirus, family Virgaviridae) lead to major yield losses in economically important crops around the world. In this review, we go beyond the canonical gene expression framework by integrating recent discoveries of reverse open reading frames (rORFs) on the negative-strand RNA. These rORFs have only been experimentally validated in cucumber green mottle mosaic virus (CGMMV), with predicted sequence-conserved homologs across a subset of the genus, including TMV, ToBRFV, and PMMoV. However, they are not universally present in all tobamoviruses. We systematically dissect the infection cycle-from disassembly and replication to cell-to-cell and systemic movement-with an emphasis on the host factors hijacked at each stage. We synthesize current understanding of plant antiviral immunity, focusing on RNA silencing and NLR receptor-mediated resistance as two pillars of defense, along with the transcription factors and microRNAs that orchestrate these responses. We critically evaluate the experimental evidence for both plant defenses and viral counter-strategies, noting that many mechanistic models derive from limited model systems. We further characterize host genetic resistance and susceptibility factors applicable to crop breeding. These resources include dominant NLR and non-NLR resistance, as well as recessive resistance derived from modified host susceptibility genes. We address how viral mutations, recombination and fitness trade-offs undermine resistance durability. We then evaluate their practical deployment through conventional breeding, the exploitation of quantitative resistance, and genome editing, and outline associated agronomic drawbacks and regulatory constraints. Using ToBRFV as a case study, we analyze its epidemiological traits and assess the current arsenal of surveillance tools, from field diagnostics to remote sensing. Finally, we survey management strategies across a spectrum of maturity. Some approaches, including sanitation protocols and conventionally bred resistant cultivars, have proven effective under field conditions. The first dsRNA-based biopesticide has recently been registered in China, while other biological control agents and low-risk chemical approaches remain largely at the experimental stage. We also discuss the bottlenecks that impede lab-to-field transition and highlight promising solutions such as precision breeding and evolution-oriented cultivar deployment. By bridging molecular virology, epidemiology, and integrated disease management, this review provides a critical, bench-to-field framework for the sustainable control of tobamoviruses.

TMV

Comparative mitogenomics of Ocnus glacialis reveals lineage-specific evolutionary rates and complex gene rearrangements in Dendrochirotida.

The order Dendrochirotida (Class Holothuroidea) is a species-rich echinoderm group, yet its internal evolutionary history remains poorly resolved due to limited mitogenomic resources. In this study, we characterized the first complete mitochondrial genome of Ocnus glacialis and conducted comparative analyses to elucidate its phylogenetic position and molecular evolutionary patterns. The circular mitogenome of O. glacialis is 16,776 bp in length, containing the canonical set of 37 genes. Among the analyzed dendrochirotids, O. glacialis exhibited the highest A + T content (70.88%) and a near-zero AT-skew, a compositional profile often linked to lineage-specific evolution in specialized environments. Selection pressure analyses, including branch-model tests, revealed that these compositional features are associated with relaxed purifying selection and an accelerated rate of sequence evolution. Branch-site analyses further identified specific codon sites in cytb, nad2, nad4l, nad5, and nad6 under positive or relaxed constraints. Structurally, O. glacialis displayed the most complex gene rearrangement pattern among the studied species, characterized by multiple tandem duplication-random loss (TDRL) events and extensive intergenic sequences. Furthermore, divergence time estimation suggests that these structural and compositional shifts occurred in tandem with the lineage's diversification. We propose that these mitogenomic signatures reflect a synergistic outcome of habitat transition toward Arctic cold-water and deep-sea environments, coupled with demographic factors such as reduced effective population sizes inherent to its benthic life history. By resolving taxonomic uncertainties, this study provides a robust temporal and molecular framework for understanding the evolutionary history and ecological diversification of the Ocnus lineage.

Animals