Coat protein expression strategy of maize rayado fino virus and evidence for requirement of CP1 for leafhopper transmission.

Marafiviruses, including maize rayado fino virus (MRFV) and oat blue dwarf virus (OBDV), encode two carboxy co-terminal coat proteins, CP1 and CP2, which encapsidate the genome to form icosahedral virions. While CP2 expression is expected to be solely driven from a second start codon of a subgenomic RNA under a marafibox promoter sequence, the larger CP1 with an in-frame N-terminal extension relative to CP2 could potentially be expressed either by proteolytic release from the MRFV polyprotein or from subgenomic RNA translation. We examined MRFV CP expression strategy with a series of mutations in the CP coding region and identified mutants viable and nonviable for systemic plant infection.

Critical residues for proteolysis activity of maize chlorotic dwarf virus (MCDV) 3C-like protease and comparison of activity of orthologous waikavirus proteases.

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.

Simultaneous gene expression and multi-gene silencing in Zea mays using maize dwarf mosaic virus.

Background: Maize dwarf mosaic virus (MDMV), a member of the genus Potyvirus, infects maize and is non-persistently transmitted by aphids. Several plant viruses have been developed as tools for gene expression and gene silencing in plants. The capacity of MDMV for both gene expression and gene silencing were examined.

Maize Yellow Mosaic Virus Interacts with Maize Chlorotic Mottle Virus and Sugarcane Mosaic Virus in Mixed Infections, But Does Not Cause Maize Lethal Necrosis.

A maize-infecting polerovirus, variously named maize yellow dwarf virus RMV2 (MYDV RMV2), MYDV-like, and maize yellow mosaic virus (MaYMV), is frequently found in mixed infections in plants also infected with maize chlorotic mottle virus (MCMV) and sugarcane mosaic virus (SCMV), known to synergistically cause maize lethal necrosis (MLN). MaYMV was discovered in deep sequencing studies precipitated by recent MLN emergence and is prevalent at global locations with MLN, but its role in or contribution to disease was not known. We examined how MaYMV impacted disease development in mixed infections with MCMV, SCMV, and both MCMV and SCMV compared with mock-inoculated plants.

Detection of Diverse Maize Chlorotic Mottle Virus Isolates in Maize Seed.

Maize chlorotic mottle virus (MCMV) has driven the emergence of maize lethal necrosis worldwide, where it threatens maize production in areas of East Africa, South America, and Asia. It is thought that MCMV transmission through seed may be important for introduction of the virus in new regions. Identification of infested seed lots is critical for preventing the spread of MCMV through seed.

Engineering for virus-induced gene silencing.

(MRFV) is the type species of the genus in the family . It infects maize (), its natural host, to which it is transmitted by leafhoppers including and in a persistent-propagative manner. The MRFV monopartite RNA genome encodes a precursor polyprotein that is processed into replication-associated proteins.

A Recently Discovered Maize Polerovirus Causes Leaf Reddening Symptoms in Several Maize Genotypes and is Transmitted by Both the Corn Leaf Aphid () and the Bird Cherry-Oat Aphid ().

A maize-infecting polerovirus variously named maize yellow dwarf virus RMV2 (MYDV-RMV2) and maize yellow mosaic virus (MaYMV) has been discovered and previously described in East Africa, Asia, and South America. It was identified in virus surveys in these locations instigated by outbreaks of maize lethal necrosis (MLN), known to be caused by coinfections of unrelated maize chlorotic mottle virus (MCMV) and any of several maize-infecting potyviruses, and was often found in coinfections with MLN viruses. Although sequenced in many locations globally and named for symptoms of related or coinfecting viruses, and with an infectious clone reported that experimentally infects , rudimentary biological characterization of MaYMV in maize, including insect vector(s) and symptoms in single infections, has not been reported until now.

Maize lethal necrosis viruses and other maize viruses in Rwanda.

Maize lethal necrosis (MLN) is emergent in East Africa, first reported in 2011 in Kenya, and is devastating to maize production in the region. MLN is caused by coinfection of maize with the emergent maize chlorotic mottle virus (MCMV) and any of several maize-infecting potyviruses endemic in East Africa and worldwide. Here, we examined the distribution of MCMV and sugarcane mosaic virus (SCMV), the major viruses contributing to MLN in Rwanda.

Barley stripe mosaic virus (BSMV) as a virus-induced gene silencing vector in maize seedlings.

Barley stripe mosaic virus (BSMV) was the first reported and still widely used virus-induced gene silencing (VIGS) vector for monocotyledons including wheat and barley. Despite BSMV's reported infectivity on maize (Zea mays), the use of the virus as a vector in maize has not been optimized. Here, we assayed infectivity of BSMV in different maize cultivars by vascular puncture inoculation.

Complete Genome Sequence of a New Maize-Associated Cytorhabdovirus.

A new 11,877-nucleotide cytorhabdovirus sequence with 6 open reading frames has been identified in a maize sample. It shares 50 and 51% genome-wide nucleotide sequence identity with northern cereal mosaic cytorhabdovirus and barley yellow striate mosaic cytorhabdovirus, respectively.

The capsid protein of Turnip crinkle virus overcomes two separate defense barriers to facilitate systemic movement of the virus in Arabidopsis.

The capsid protein (CP) of Turnip crinkle virus (TCV) is a multifunctional protein needed for virus assembly, suppression of RNA silencing-based antiviral defense, and long-distance movement in infected plants. In this report, we have examined genetic requirements for the different functions of TCV CP and evaluated the interdependence of these functions. A series of TCV mutants containing alterations in the CP coding region were generated.

Shotgun sequencing of the negative-sense RNA genome of the rhabdovirus Maize mosaic virus.

The maize-infecting nucleorhabdovirus, Maize mosaic virus (MMV), was sequenced to near completion using the random shotgun approach. Sequences of 102 clones from a cDNA library constructed from randomly-primed viral RNA were compiled into a 12,133 nucleotide (nt) contig containing six open reading frames. The contig consisted of 97 sequences averaging 660 bp in length.

Complete genome sequence and in planta subcellular localization of maize fine streak virus proteins.

The genome of the nucleorhabdovirus maize fine streak virus (MFSV) consists of 13,782 nucleotides of nonsegmented, negative-sense, single-stranded RNA. The antigenomic strand consisted of seven open reading frames (ORFs), and transcripts of all ORFs were detected in infected plants. ORF1, ORF6, and ORF7 had significant similarities to the nucleocapsid protein (N), glycoprotein (G), and polymerase (L) genes of other rhabdoviruses, respectively, whereas the ORF2, ORF3, ORF4, and ORF5 proteins had no significant similarities.

Accumulation of maize chlorotic dwarf virus proteins in its plant host and leafhopper vector.

The genome of Maize chlorotic dwarf virus (MCDV; genus Waikavirus; family Sequiviridae) consists of a monopartite positive-sense RNA genome encoding a single large polyprotein. Antibodies were produced to His-fusions of three undefined regions of the MCDV polyprotein: the N-terminus of the polyprotein (R78), a region between coat proteins (CPs) and the nucleotide-binding site (NBS) (R37), and a region between the NBS and a 3C-like protease (R69). The R78 antibodies react with proteins of 50 kDa (P50), 35 kDa (P35), and 25 kDa (P25) in virus preparations, and with P35 in plant extracts.