RESUMEN
The eukaryotic mRNA surveillance pathway, a pivotal guardian of mRNA fidelity, stands at the nexus of diverse biological processes, including antiviral immunity. Despite the recognized function of splicing factors on mRNA fate, the intricate interplay shaping the mRNA surveillance pathway remains elusive. We illustrate that the conserved splicing factor U2 snRNP auxiliary factor large subunit B (U2AF65B) modulates splicing of mRNA surveillance complex, contributing to transcriptomic homeostasis in maize. The functionality of the mRNA surveillance pathway requires ZmU2AF65B-mediated normal splicing of upstream frameshift 3 (ZmUPF3) pre-mRNA, encoding a core factor in this pathway. Intriguingly, sugarcane mosaic virus (SCMV)-coded nuclear inclusion protein a protease (NIa-Pro) hinders the splicing function of ZmU2AF65B. Furthermore, NIa-Pro disrupts ZmU2AF65B binding to ZmUPF3 pre-mRNA, leading to dysregulated splicing of ZmUPF3 transcripts and, consequently, impairing mRNA surveillance, thus facilitating viral infection. Together, this study establishes that splicing governs the mRNA surveillance pathway and identifies a pathogenic protein capable of disrupting this regulation to compromise RNA immunity.
Asunto(s)
Potyvirus , Empalme del ARN , ARN Mensajero , Zea mays , Zea mays/virología , Zea mays/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Potyvirus/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas Virales/genética , Proteínas Virales/metabolismo , Enfermedades de las Plantas/virología , Enfermedades de las Plantas/genética , Factor de Empalme U2AF/metabolismo , Factor de Empalme U2AF/genética , Precursores del ARN/genética , Precursores del ARN/metabolismo , Regulación de la Expresión Génica de las PlantasRESUMEN
Maize rough dwarf disease (MRDD) threatens maize production globally. The P7-1 effector of the rice black-streaked dwarf virus (RBSDV) targets maize Rab GDP dissociation inhibitor alpha (ZmGDIα) to cause MRDD. However, P7-1 has difficulty recruiting a ZmGDIα variant with an alternative helitron-derived exon 10 (ZmGDIα-hel), resulting in recessive resistance. Here, we demonstrate that P7-1 can recruit another maize protein, gibberellin 2-oxidase 13 (ZmGA2ox7.3), which also exhibits tighter binding affinity for ZmGDIα than ZmGDIα-hel. The oligomerization of ZmGA2ox7.3 is vital for its function in converting bioactive gibberellins into inactive forms. Moreover, the enzymatic activity of ZmGA2ox7.3 oligomers increases when forming hetero-oligomers with P7-1/ZmGDIα, but decreases when ZmGDIα-hel replaces ZmGDIα. Viral infection significantly promotes ZmGA2ox7.3 expression and oligomerization in ZmGDIα-containing susceptible maize, resulting in reduced bioactive GA1/GA4 levels. This causes an auxin/cytokinin imbalance and ultimately manifests as MRDD syndrome. Conversely, in resistant maize, ZmGDIα-hel counters these virus-induced changes, thereby mitigating MRDD severity.
Asunto(s)
Giberelinas , Enfermedades de las Plantas , Proteínas de Plantas , Zea mays , Zea mays/virología , Zea mays/metabolismo , Enfermedades de las Plantas/virología , Giberelinas/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Virus de Plantas/fisiología , Resistencia a la Enfermedad , Regulación de la Expresión Génica de las Plantas , Plantas Modificadas Genéticamente , Proteínas Virales/metabolismo , Proteínas Virales/genéticaRESUMEN
Pathogen infection induces massive reprogramming of host primary metabolism. Lipid and fatty acid (FA) metabolism is generally disrupted by pathogens and co-opted for their proliferation. Lipid droplets (LDs) that play important roles in regulating cellular lipid metabolism are utilized by a variety of pathogens in mammalian cells. However, the function of LDs during pathogenic infection in plants remains unknown. We show here that infection by rice black streaked dwarf virus (RBSDV) affects the lipid metabolism of maize, which causes elevated accumulation of C18 polyunsaturated fatty acids (PUFAs) leading to viral proliferation and symptom development. The overexpression of one of the two novel LD-associated proteins (LDAPs) of maize (ZmLDAP1 and ZmLDAP2) induces LD clustering. The core capsid protein P8 of RBSDV interacts with ZmLDAP2 and prevents its degradation through the ubiquitin-proteasome system mediated by a UBX domain-containing protein, PUX10. In addition, silencing of ZmLDAP2 downregulates the expression of FA desaturase genes in maize, leading to a decrease in C18 PUFAs levels and suppression of RBSDV accumulation. Our findings reveal that plant virus may recruit LDAP to regulate cellular FA metabolism to promote viral multiplication and infection. These results expand the knowledge of LD functions and viral infection mechanisms in plants.
Asunto(s)
Ácidos Grasos , Enfermedades de las Plantas , Proteínas de Plantas , Replicación Viral , Zea mays , Zea mays/virología , Zea mays/metabolismo , Zea mays/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Enfermedades de las Plantas/virología , Ácidos Grasos/metabolismo , Metabolismo de los Lípidos , Proteínas Asociadas a Gotas Lipídicas/metabolismo , Proteínas Asociadas a Gotas Lipídicas/genética , Gotas Lipídicas/metabolismo , Gotas Lipídicas/virología , Virus de Plantas/fisiología , Regulación de la Expresión Génica de las Plantas , Reoviridae/fisiologíaRESUMEN
To describe the transmission dynamics of maize streak virus infection, in the paper, we first formulate a stochastic maize streak virus infection model, in which the stochastic fluctuations are depicted by a logarithmic Ornstein-Uhlenbeck process. This approach is reasonable to simulate the random impacts of main parameters both from the biological significance and the mathematical perspective. Then we investigate the detailed dynamics of the stochastic system, including the existence and uniqueness of the global solution, the existence of a stationary distribution, the exponential extinction of the infected maize and infected leafhopper vector. Especially, by solving the five-dimensional algebraic equations corresponding to the stochastic system, we obtain the specific expression of the probability density function near the quasi-endemic equilibrium of the stochastic system, which provides valuable insights into the stationary distribution. Finally, the model is discretized using the Milstein higher-order numerical method to illustrate our theoretical results numerically. Our findings provide a groundwork for better methods of preventing the spread of this type of virus.
Asunto(s)
Virus de la Veta de Maíz , Conceptos Matemáticos , Modelos Biológicos , Enfermedades de las Plantas , Procesos Estocásticos , Zea mays , Enfermedades de las Plantas/virología , Enfermedades de las Plantas/estadística & datos numéricos , Zea mays/virología , Animales , Virus de la Veta de Maíz/fisiología , Simulación por Computador , Insectos Vectores/virología , Epidemias/estadística & datos numéricos , Hemípteros/virologíaRESUMEN
Rice black-streaked dwarf virus (RBSDV) is an etiological agent of a destructive disease infecting some economically important crops from the Gramineae family in Asia. While RBSDV causes high yield losses, genetic characteristics of replicative viral populations have not been investigated within different host plants and insect vectors. Herein, eleven publicly available RNA-Seq datasets from Chinese RBSDV-infected rice, maize, and viruliferous planthopper (Laodelphax striatellus) were obtained from the NCBI database. The patterns of SNP and RNA expression profiles of expected RBSDV populations were analyzed by CLC Workbench 20 and Geneious Prime software. These analyses discovered 2,646 mutations with codon changes in RBSDV whole transcriptome and forty-seven co-mutated hotspots with high variant frequency within the crucial regions of S5-1, S5-2, S6, S7-1, S7-2, S9, and S10 open reading frames (ORFs) which are responsible for some virulence and host range functions. Moreover, three joint mutations are located on the three-dimensional protein of P9-1. The infected RBSDV-susceptible rice cultivar KTWYJ3 and indigenous planthopper datasets showed more co-mutated hotspot numbers than others. Our analyses showed the expression patterns of viral genomic fragments varied depending on the host type. Unlike planthopper, S5-1, S2, S6, and S9-1 ORFs, respectively had the greatest read numbers in host plants; and S5-2, S9-2, and S7-2 were expressed in the lowest level. These findings underscore virus/host complexes are effective in the genetic variations and gene expression profiles of plant viruses. Our analysis revealed no evidence of recombination events. Interestingly, the negative selection was observed at 12 RBSDV ORFs, except for position 1015 in the P1 protein, where a positive selection was detected. The research highlights the potential of SRA datasets for analysis of the virus cycle and enhances our understanding of RBSDV's genetic diversity and host specificity.
Asunto(s)
Insectos Vectores , Oryza , Enfermedades de las Plantas , Virus de Plantas , Animales , Oryza/virología , Oryza/genética , Insectos Vectores/virología , Insectos Vectores/genética , Virus de Plantas/genética , Enfermedades de las Plantas/virología , Enfermedades de las Plantas/genética , Hemípteros/virología , Hemípteros/genética , Variación Genética , RNA-Seq , Transcriptoma , Reoviridae/genética , Zea mays/virología , Zea mays/genética , Polimorfismo de Nucleótido Simple , Mutación , Perfilación de la Expresión Génica , Sistemas de Lectura Abierta/genéticaRESUMEN
Barley yellow dwarf (BYD) is one of the economically most important virus diseases of cereals worldwide, causing yield losses up to 80%. The means to control BYD are limited, and the use of genetically resistant cultivars is the most economical and environmentally friendly approach. The objectives of this study were i) to identify the causative gene for BYD virus (BYDV)-PAV resistance in maize, ii) to identify single nucleotide polymorphisms and/or structural variations in the gene sequences, which may cause differing susceptibilities to BYDV-PAV of maize inbreds, and iii) to characterize the effect of BYDV-PAV infection on gene expression of susceptible, tolerant, and resistant maize inbreds. Using two biparental mapping populations, we could reduce a previously published quantitative trait locus for BYDV-PAV resistance in maize to ~ 0.3 Mbp, comprising nine genes. Association mapping and gene expression analysis further reduced the number of candidate genes for BYDV-PAV resistance in maize to two: Zm00001eb428010 and Zm00001eb428020. The predicted functions of these genes suggest that they confer BYDV-PAV resistance either via interfering with virus replication or by inducing reactive oxygen species signaling. The gene sequence of Zm00001eb428010 is affected by a 54 bp deletion in the 5`-UTR and a protein altering variant in BYDV-PAV-resistant maize inbreds but not in BYDV-PAV-susceptible and -tolerant inbreds. This finding suggests that altered abundance and/or properties of the proteins encoded by Zm00001eb428010 may lead to BYDV-PAV resistance.
Asunto(s)
Mapeo Cromosómico , Resistencia a la Enfermedad , Enfermedades de las Plantas , Polimorfismo de Nucleótido Simple , Sitios de Carácter Cuantitativo , Zea mays , Zea mays/genética , Zea mays/virología , Resistencia a la Enfermedad/genética , Enfermedades de las Plantas/virología , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/inmunología , Genes de Plantas , Luteovirus , FenotipoRESUMEN
MicroRNAs (miRNAs) are widely involved in various biological processes of plants and contribute to plant resistance against various pathogens. In this study, upon sugarcane mosaic virus (SCMV) infection, the accumulation of maize (Zea mays) miR398b (ZmmiR398b) was significantly reduced in resistant inbred line Chang7-2, while it was increased in susceptible inbred line Mo17. Degradome sequencing analysis coupled with transient co-expression assays revealed that ZmmiR398b can target Cu/Zn-superoxidase dismutase2 (ZmCSD2), ZmCSD4, and ZmCSD9 in vivo, of which the expression levels were all upregulated by SCMV infection in Chang7-2 and Mo17. Moreover, overexpressing ZmmiR398b (OE398b) exhibited increased susceptibility to SCMV infection, probably by increasing reactive oxygen species (ROS) accumulation, which were consistent with ZmCSD2/4/9-silenced maize plants. By contrast, silencing ZmmiR398b (STTM398b) through short tandem target mimic (STTM) technology enhanced maize resistance to SCMV infection and decreased ROS levels. Interestingly, copper (Cu)-gradient hydroponic experiments demonstrated that Cu deficiency promoted SCMV infection while Cu sufficiency inhibited SCMV infection by regulating accumulations of ZmmiR398b and ZmCSD2/4/9 in maize. These results revealed that manipulating the ZmmiR398b-ZmCSD2/4/9-ROS module provides a prospective strategy for developing SCMV-tolerant maize varieties.
Asunto(s)
Resistencia a la Enfermedad , MicroARNs , Enfermedades de las Plantas , Potyvirus , Zea mays , Zea mays/virología , Zea mays/genética , Potyvirus/fisiología , Potyvirus/patogenicidad , Enfermedades de las Plantas/virología , Enfermedades de las Plantas/genética , Resistencia a la Enfermedad/genética , MicroARNs/genética , MicroARNs/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Regulación de la Expresión Génica de las Plantas , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Exportin 1 (XPO1) is the major karyopherin-ß nuclear receptor mediating the nuclear export of hundreds of proteins and some classes of RNA and regulates several critical processes in the cell, including cell-cycle progression, transcription and translation. Viruses have co-opted XPO1 to promote nucleocytoplasmic transport of viral proteins and RNA. Maize mosaic virus (MMV) is a plant-infecting rhabdovirus transmitted in a circulative propagative manner by the corn planthopper, Peregrinus maidis. MMV replicates in the nucleus of plant and insect hosts, and it remains unknown whether MMV co-opts P. maidis XPO1 (PmXPO1) to complete its life cycle. Because XPO1 plays multiple regulatory roles in cell functions and virus infection, we hypothesized that RNAi-mediated silencing of XPO1 would negatively affect MMV accumulation and insect physiology. Although PmXPO1 expression was not modulated during MMV infection, PmXPO1 knockdown negatively affected MMV accumulation in P. maidis at 12 and 15 days after microinjection. Likewise, PmXPO1 knockdown negatively affected P. maidis survival and reproduction. PmXPO1 exhibited tissue-specific expression patterns with higher expression in the ovaries compared with the guts of adult females. Survival rate was significantly lower for PmXPO1 knockdown females, compared with controls, but no effect was observed for males. PmXPO1 knockdown experiments revealed a role for PmXPO1 in ovary function and egg production. Oviposition and egg hatch on plants were dramatically reduced in females treated with dsRNA PmXPO1. These results suggest that PmXPO1 is a positive regulator of P. maidis reproduction and that it plays a proviral role in the insect vector supporting MMV infection.
Asunto(s)
Proteína Exportina 1 , Hemípteros , Insectos Vectores , Carioferinas , Ovario , Interferencia de ARN , Receptores Citoplasmáticos y Nucleares , Animales , Femenino , Hemípteros/virología , Hemípteros/genética , Hemípteros/crecimiento & desarrollo , Carioferinas/metabolismo , Carioferinas/genética , Ovario/virología , Ovario/metabolismo , Ovario/crecimiento & desarrollo , Receptores Citoplasmáticos y Nucleares/metabolismo , Receptores Citoplasmáticos y Nucleares/genética , Insectos Vectores/virología , Insectos Vectores/genética , Rhabdoviridae/fisiología , Proteínas de Insectos/metabolismo , Proteínas de Insectos/genética , Zea mays/virología , Zea mays/genética , Técnicas de Silenciamiento del GenRESUMEN
In maize, two pyruvate orthophosphate dikinase (PPDK) regulatory proteins, ZmPDRP1 and ZmPDRP2, are respectively specific to the chloroplast of mesophyll cells (MCs) and bundle sheath cells (BSCs). Functionally, ZmPDRP1/2 catalyse both phosphorylation/inactivation and dephosphorylation/activation of ZmPPDK, which is implicated as a major rate-limiting enzyme in C4 photosynthesis of maize. Our study here showed that maize plants lacking ZmPDRP1 or silencing of ZmPDRP1/2 confer resistance to a prevalent potyvirus sugarcane mosaic virus (SCMV). We verified that the C-terminal domain (CTD) of ZmPDRP1 plays a key role in promoting viral infection while independent of enzyme activity. Intriguingly, ZmPDRP1 and ZmPDRP2 re-localize to cytoplasmic viral replication complexes (VRCs) following SCMV infection. We identified that SCMV-encoded cytoplasmic inclusions protein CI targets directly ZmPDRP1 or ZmPDRP2 or their CTDs, leading to their re-localization to cytoplasmic VRCs. Moreover, we found that CI could be degraded by the 26S proteasome system, while ZmPDRP1 and ZmPDRP2 could up-regulate the accumulation level of CI through their CTDs by a yet unknown mechanism. Most importantly, with genetic, cell biological and biochemical approaches, we provide evidence that BSCs-specific ZmPDRP2 could accumulate in MCs of Zmpdrp1 knockout (KO) lines, revealing a unique regulatory mechanism crossing different cell types to maintain balanced ZmPPDK phosphorylation, thereby to keep maize normal growth. Together, our findings uncover the genetic link of the two cell-specific maize PDRPs, both of which are co-opted to VRCs to promote viral protein accumulation for robust virus infection.
Asunto(s)
Enfermedades de las Plantas , Proteínas de Plantas , Potyvirus , Replicación Viral , Zea mays , Potyvirus/fisiología , Zea mays/virología , Zea mays/genética , Zea mays/metabolismo , Replicación Viral/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Enfermedades de las Plantas/virología , Fotosíntesis/genética , Piruvato Ortofosfato Diquinasa/metabolismo , Piruvato Ortofosfato Diquinasa/genética , Cloroplastos/metabolismo , Cloroplastos/virologíaRESUMEN
Maize dwarf mosaic (MDM) is one of the most important virus diseases of maize worldwide. Caused by the potyviruses maize dwarf mosaic virus (MDMV) or sugarcane mosaic virus (SCMV), MDM can cause up to 90% yield loss in susceptible hybrids. One of the most effective management strategies for MDM is growing potyvirus-resistant corn varieties. However, yield impacts associated with MDM and the corresponding efficacy of genetic resistance present in modern United States commercial hybrid lines is uncharacterized. In this study, we evaluated the disease response of 78 commercial hybrids to MDMV and SCMV and quantified yield losses associated with infection over multiple trials. We determined that while 97% of the hybrids tested were resistant to MDMV, 100% were susceptible to SCMV, with mean disease incidence per line averaging between 45 and 78% across six trial years. Despite only one hybrid displaying visible mosaic symptoms when inoculated with MDMV, MDMV reduced average yields by approximately 5% across all hybrids compared with the mock-inoculated treatment. The yield impact of SCMV was more severe, reducing average yields by 10% across replicated experiments. These results indicate that while most commercial hybrids are resistant to MDMV, possibly due to the presence of the major Scmv1 resistance locus on chromosome 6, additional potyvirus resistance genes are needed to manage SCMV-induced MDM. Pyramiding resistance loci, such as Scmv2 on chromosome 3 or Scmv3 on chromosome 10 in addition to Scmv1, could be an effective strategy to mitigate the yield impact of MDM disease.
Asunto(s)
Resistencia a la Enfermedad , Enfermedades de las Plantas , Potyvirus , Zea mays , Enfermedades de las Plantas/virología , Enfermedades de las Plantas/prevención & control , Zea mays/virología , Zea mays/genética , Potyvirus/fisiología , Potyvirus/genética , Resistencia a la Enfermedad/genética , Hibridación GenéticaRESUMEN
Maize rough dwarf disease (MRDD) threatens the sustainable production of major cereal crops. Recently, Xu et al. reported a new resistance gene, ZmGLK36, which promotes MRDD resistance in maize by increasing jasmonic acid (JA)-mediated defence. This discovery provides opportunities to develop resistance to rice black-streaked dwarf virus (RBSDV) in other cereal crops such as rice and wheat.
Asunto(s)
Resistencia a la Enfermedad , Oryza , Enfermedades de las Plantas , Proteínas de Plantas , Triticum , Oryza/virología , Oryza/genética , Enfermedades de las Plantas/virología , Triticum/virología , Triticum/genética , Resistencia a la Enfermedad/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Zea mays/virología , Zea mays/genética , Regulación de la Expresión Génica de las Plantas , Virus de Plantas/fisiologíaRESUMEN
Maize lethal necrosis is a destructive virus disease of maize caused by maize chlorotic mottle virus (MCMV) in combination with a virus in the family Potyviridae. Emergence of MLN is typically associated with the introduction of MCMV or its vectors and understanding its spread through seed is critical for disease management. Previous studies suggest that although MCMV is detected on seed, the seed transmission rate of this virus is low. However, mechanisms influencing its transmission are poorly understood. Elucidating these mechanisms is crucial for informing strategies to prevent spread on contaminated seed. In this study, we evaluated the rate of MCMV seed transmission using seed collected from plants that were artificially inoculated with MCMV isolates from Hawaii and Kenya. Grow-out tests indicated that MCMV transmission through seed was rare, with a rate of 0.004% among the more than 85,000 seed evaluated, despite detection of MCMV at high levels in the seed lots. To understand factors that limit transmission from seed, MCMV distribution in seed tissues was examined using serology and immunolocalization. The virus was present at high levels in maternal tissues, the pericarp and pedicel, but absent from filial endosperm and embryo seed tissues. The ability to transmit MCMV from seed to uninfected plants was tested to evaluate virus viability. Transmission was negatively associated with both seed maturity and moisture content. Transmission of MCMV from infested seed dried to less than 15% moisture was not detected, suggesting proper handling could be important for minimizing spread of MCMV through seed.
Asunto(s)
Enfermedades de las Plantas , Potyviridae , Tombusviridae , Zea mays , Kenia , Enfermedades de las Plantas/virología , Zea mays/virología , Hawaii , Semillas/virologíaRESUMEN
Maize rough dwarf disease (MRDD) is a viral disease that causes substantial yield loss, especially in China's summer planted maize area. Discovery of resistance genes would help in developing high-yielding resistant maize hybrids. Genome-wide association studies (GWASs) have advanced quickly and are now a powerful tool for dissecting complex genetic architectures. In this study, the disease severity index (DSI) of 292 maize inbred lines and an F6 linkage population were investigated across multiple environments for two years. Using the genotypes obtained from the Maize SNP 50K chip, a GWAS was performed with four analytical models. The results showed that 22 SNPs distributed on chromosomes 1, 3, 4, 6, 7 and 8 were significantly associated with resistance to MRDD (P<0.0001). The SNPs on chromosomes 3, 6 and 8 were consistent with the quantitative trait locus (QTL) regions from linkage mapping in an RIL population. Candidate genes identified by GWAS included an LRR receptor-like serine/threonine-protein kinase (GRMZM2G141288), and a DRE-binding protein (GRMZM2G006745). In addition, we performed an allele variation analysis of the SNP loci selected by GWAS and linkage mapping and found that the main alleles of the two SNP loci PZE_101170408 and PZE_106082685 on chromosome 1 differed in terms of disease-resistant materials and disease-susceptible materials. The identified SNPs and genes provide useful information for MRDD-related gene cloning and insights on the underlying disease resistance mechanisms, and they can be used in marker-assisted breeding to develop MRDD-resistant maize.
Asunto(s)
Resistencia a la Enfermedad/genética , Ligamiento Genético , Fitomejoramiento/métodos , Sitios de Carácter Cuantitativo , Zea mays/genética , Zea mays/virología , China , Mapeo Cromosómico , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Estudio de Asociación del Genoma Completo , Genotipo , Fenotipo , Polimorfismo de Nucleótido SimpleRESUMEN
Maize chlorotic dwarf virus (MCDV) encodes a 3C-like protease that cleaves the N-terminal polyprotein (R78) as previously demonstrated. Here, we examined amino acid residues required for catalytic activity of the protease, including those in the predicted catalytic triad, amino acid residues H2667, D2704, and C2798, as well as H2817 hypothesized to be important in substrate binding. These and other residues were targeted for mutagenesis and tested for proteolytic cleavage activity on the N-terminal 78 kDa MCDV-S polyprotein substrate to identify mutants that abolished catalytic activity. Mutations that altered the predicted catalytic triad residues and H2817 disrupted MCDV-S protease activity, as did mutagenesis of a conserved tyrosine residue, Y2774. The protease activity and R78 cleavage of orthologs from divergent MCDV isolates MCDV-Tn and MCDV-M1, and other waikavirus species including rice tungro spherical virus (RTSV) and bellflower vein chlorosis virus (BVCV) were also examined.
Asunto(s)
Proteasas Virales 3C/química , Regulación Viral de la Expresión Génica , Genoma Viral , Waikavirus/genética , Proteasas Virales 3C/genética , Proteasas Virales 3C/metabolismo , Secuencia de Aminoácidos , Sitios de Unión , Sistema Libre de Células/metabolismo , Modelos Moleculares , Mutación , Unión Proteica , Biosíntesis de Proteínas , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Proteolisis , Semillas/química , Semillas/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Relación Estructura-Actividad , Especificidad por Sustrato , Transcripción Genética , Triticum/virología , Waikavirus/enzimología , Zea mays/virologíaRESUMEN
Sugarcane mosaic virus (SCMV), which belongs to the Potyvirus genus of the family Potyviridae, causes mosaic diseases in canna, sugarcane and maize worldwide. Previously, the genetic variations, timescale, codon usage patterns and host adaptions of SCMV were determined. However, the dinucleotide composition and the dinucleotide bias from hosts or the protein coding regions of the virus have yet to be investigated. In this study, comprehensive analyses of the dinucleotide composition and dinucleotide bias from hosts, lineages and protein coding regions of SCMV were performed using 131 complete genomic sequences. We found that UpG and CpA were largely overrepresented while UpA, CpC, and CpG were largely underrepresented in the polyprotein and 11 protein coding region data sets. SCMV dinucleotide composition bias is more strongly dependent on the protein coding regions than on hosts. A weak association between the dinucleotide composition and SCMV lineages was also observed. Our analysis provides a novel perspective on the molecular evolutionary mechanisms of SCMV and may provide a better understanding of future research on the origin and evolutionary patterns of SCMV.
Asunto(s)
Repeticiones de Dinucleótido , Interacciones Huésped-Patógeno , Sistemas de Lectura Abierta , Potyvirus/genética , Saccharum/virología , Zea mays/virología , Zingiberales/virologíaRESUMEN
Maize rough dwarf disease (MRDD) is caused by a virus and seriously affects maize quality and yield worldwide. MRDD can be most effectively controlled with disease-resistant hybrids of corn. Here, MRDD-resistant (Qi319) and -susceptible (Ye478) parental inbred maize lines and their 314 recombinant inbred lines (RILs) that were derived from a cross between them were evaluated across three environments. A stable resistance QTL, qMrdd2, was identified and mapped using best linear unbiased prediction (BLUP) values to a 0.55-Mb region between the markers MK807 and MK811 on chromosome 2 (B73 RefGen_v3) and was found to explain 8.6 to 11.0% of the total phenotypic variance in MRDD resistance. We validated the effect of qMrdd2 using a chromosome segment substitution line (CSSL) that was derived from a cross between maize inbred Qi319 as the MRDD resistance donor and Ye478 as the recipient. Disease severity index of the CSSL haplotype II harboring qMrdd2 was significantly lower than that of the susceptible parent Ye478. Subsequently, we fine-mapped qMrdd2 to a 315-kb region flanked by the markers RD81 and RD87, thus testing recombinant-derived progeny using selfed backcrossed families. In this study, we identified a novel QTL for MRDD resistance by combining the RIL and CSSL populations, thus providing important genetic information that can be used for breeding MRDD-resistant varieties of maize.
Asunto(s)
Resistencia a la Enfermedad , Enfermedades de las Plantas , Sitios de Carácter Cuantitativo , Zea mays , Resistencia a la Enfermedad/genética , Haplotipos , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/virología , Zea mays/genética , Zea mays/virologíaRESUMEN
The corn leafhopper (Dalbulus maidis) is an important vector of maize rayado fino virus (MRFV), a positive-strand RNA (+ssRNA) marafivirus which it transmits in a persistent propagative manner. The interaction of D. maidis with MRFV, including infection of the insect and subsequent transmission to new plants, is not well understood at the molecular level. To examine the leafhopper-virus interaction, a D. maidis transcriptome was assembled and differences in transcript abundance between virus-exposed and naive D. maidis were examined at two time points (4 h and 7 days) post exposure to MRFV. The D. maidis transcriptome contained 56,116 transcripts generated from 1,727,369,026 100-nt paired-end reads from whole adult insects. The transcriptome of D. maidis shared highest identity and most orthologs with the leafhopper Graminella nigrifrons (65% of transcripts had matches with E values of <10-5) versus planthoppers Sogatella furcifera (with 23% of transcript matches below the E value cutoff) and Peregrinus maidis (with 21% transcript matches below the E value cutoff), as expected based on taxonomy. D. maidis expressed genes in the Toll, Imd, and Jak/Stat insect immune signaling pathways, RNA interference (RNAi) pathway genes, prophenoloxidase-activating system pathways, and immune recognition protein-encoding genes such as peptidoglycan recognition proteins (PGRPs), antimicrobial peptides, and other effectors. Statistical analysis (performed by R package DESeq2) identified 72 transcripts at 4 h and 67 at 7 days that were significantly responsive to MRFV exposure. Genes expected to be favorable for virus propagation, such as protein synthesis-related genes and genes encoding superoxide dismutase, were significantly upregulated after MRFV exposure. IMPORTANCE The transcriptome of the corn leafhopper, D. maidis, revealed conserved biochemical pathways for immunity and discovered transcripts responsive to MRFV-infected plants at two time points, providing a basis for functional identification of genes that either limit or promote the virus-vector interaction. Compared to other hopper species and the propagative plant viruses they transmit, D. maidis shared 15 responsive transcripts with S. furcifera (to southern rice black-streaked dwarf virus [SRBSDV]), one with G. nigrifrons (to maize fine streak virus [MFSV]), and one with P. maidis (to maize mosaic virus [MMV]), but no virus-responsive transcripts identified were shared among all four hopper vector species.
Asunto(s)
Hemípteros/genética , Hemípteros/virología , Proteínas de Insectos/genética , Insectos Vectores/genética , Insectos Vectores/virología , Tymoviridae/fisiología , Animales , Hemípteros/inmunología , Interacciones Huésped-Patógeno , Proteínas de Insectos/inmunología , Insectos Vectores/inmunología , Enfermedades de las Plantas/virología , Transcriptoma , Tymoviridae/genética , Zea mays/virologíaRESUMEN
Mal de Río Cuarto virus (MRCV) is a member of the genus Fijivirus of the family Reoviridae that causes a devastating disease in maize and is persistently and propagatively transmitted by planthopper vectors. Virus replication and assembly occur within viroplasms formed by viral and host proteins. This work describes the isolation and characterization of llama-derived Nanobodies (Nbs) recognizing the major viral viroplasm component, P9-1. Specific Nbs were selected against recombinant P9-1, with affinities in the nanomolar range as measured by surface plasmon resonance. Three selected Nbs were fused to alkaline phosphatase and eGFP to develop a sandwich ELISA test which showed a high diagnostic sensitivity (99.12%, 95% CI 95.21-99.98) and specificity (100%, 95% CI 96.31-100) and a detection limit of 0.236 ng/ml. Interestingly, these Nanobodies recognized different P9-1 conformations and were successfully employed to detect P9-1 in pull-down assays of infected maize extracts. Finally, we demonstrated that fusions of the Nbs to eGFP and RFP allowed the immunodetection of virus present in phloem cells of leaf thin sections. The Nbs developed in this work will aid the study of MRCV epidemiology, assist maize breeding programs, and be valuable tools to boost fundamental research on viroplasm structure and maturation.
Asunto(s)
Pruebas Inmunológicas/métodos , Reoviridae , Proteínas Virales , Zea mays/virología , Animales , Camélidos del Nuevo Mundo/inmunología , Ensayo de Inmunoadsorción Enzimática/métodos , Escherichia coli/genética , Enfermedades de las Plantas/virología , Plantas , Proteínas Recombinantes/análisis , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Reoviridae/inmunología , Reoviridae/aislamiento & purificación , Reoviridae/metabolismo , Proteínas Virales/análisis , Proteínas Virales/biosíntesis , Proteínas Virales/genéticaRESUMEN
Virus-induced gene silencing (VIGS) is a versatile and attractive approach for functional gene characterization in plants. Although several VIGS vectors for maize (Zea mays) have been previously developed, their utilities are limited due to low viral infection efficiency, insert instability, short maintenance of silencing, inadequate inoculation method, or abnormal requirement of growth temperature. Here, we established a Cucumber mosaic virus (CMV)-based VIGS system for efficient maize gene silencing that overcomes many limitations of VIGS currently available for maize. Using two distinct strains, CMV-ZMBJ and CMV-Fny, we generated a pseudorecombinant-chimeric (Pr) CMV. Pr CMV showed high infection efficacy but mild viral symptoms in maize. We then constructed Pr CMV-based vectors for VIGS, dubbed Pr CMV VIGS. Pr CMV VIGS is simply performed by mechanical inoculation of young maize leaves with saps of Pr CMV-infected Nicotiana benthamiana under normal growth conditions. Indeed, suppression of isopentenyl/dimethylallyl diphosphate synthase (ZmIspH) expression by Pr CMV VIGS resulted in non-inoculated leaf bleaching as early as 5 d post-inoculation (dpi) and exhibited constant and efficient systemic silencing over the whole maize growth period up to 105 dpi. Furthermore, utilizing a ligation-independent cloning (LIC) strategy, we developed a modified Pr CMV-LIC VIGS vector, allowing easy gene cloning for high-throughput silencing in maize. Thus, our Pr CMV VIGS system provides a much-improved toolbox to facilitate efficient and long-duration gene silencing for large-scale functional genomics in maize, and our pseudorecombination-chimera combination strategy provides an approach to construct efficient VIGS systems in plants.
Asunto(s)
Cucumovirus/fisiología , Silenciador del Gen , Genómica , Zea mays/virología , Quimera , Nicotiana/fisiologíaRESUMEN
The economic importance of the maize streak virus disease to the African maize production dynamic is to be appreciated now more than ever due to the preponderant influence of a changing climate. Continued dependence on a single major-effect quantitative trait locus (QTL) called Msv1 on Chromosome 1 of Maize (Zea mays L.) is not guaranteed to ensure durable resistance to the causal pathogen. With over ten decades of research on the disease and its associated host plant resistance mechanisms, it is pertinent to consider future approaches to attaining durability by looking to the synergistic roles of moderate- and minor-effect QTLs located on other chromosomes so as to facilitate a secure farming system for sub-Saharan Africa. For this review, more than 40 publications relating to maize streak disease research were methodically analysed with about 30% making specific reference to conventional, molecular and transgenic approaches employed in introgressing, maintaining and improving streak resistance in maize. A meta-analysis of mapped QTLs conferring streak resistance was conducted in a bid to reveal any inter-dependence or co-localization of resistant loci and to aid decision-making for marker-assisted breeding. With the changing climatic conditions around the globe, man's preparedness in the event of an epidemic following any evolutionary process in the streak viral genome was determined as insufficient. Modern breeding approaches including gene pyramiding that could be considered in maize breeding programmes to ensure durability for streak resistance were proposed while improving maize for other abiotic stress tolerance, particularly drought.