Chlorotic Mottle Research Articles

Reverse transcription-recombinase-aided amplification and CRISPR/Cas12a-based visual detection of maize chlorotic mottle virus

Maize chlorotic mottle virus (MCMV) is one of the important quarantine pathogens in China. It often co-infects with one or two viruses in the family Potyviridae and causes maize lethal necrosis disease. Therefore, an accurate and sensitive method for the detection of MCMV is urgently needed. Combined with reverse transcription and recombinase-aided amplification, we developed a CRISPR/Cas12a-based visual nucleic acid detection system targeting the MCMV coat protein gene. The whole process can be completed within 45 min with high sensitivity. This system could detect cDNAs diluted up to 10–5 when 2000 ng of total RNA was used for reverse transcription. The Cas12a/crRNA complex designed for MCMV detection could recognize and cleave the targeted double-stranded DNA, and ultimately cleave the single-stranded DNA probes and produce fluorescent signals. The green fluorescence produced under blue light (440–460 nm) in this procedure could be observed by the naked eye. Since this novel method is specific, rapid, sensitive and does not require special instruments and technical expertise, it should be suitable for on-site visual detection of MCMV in seeds, plants of maize and potentially in its insect vectors.

Maize production systems, farmers’ perception and current status of maize lethal necrosis in selected counties in Kenya

Maize Lethal Necrosis (MLN) is a disease of maize reported in Kenya in 2012 that results in yield losses of up to 100%. The epidemiology of MLN is complex as the disease is caused by the synergistic interaction of 2 viruses (Maize chlorotic mottle virus (MCMV) and a potyvirus). In addition, multiple reservoirs and transmission pathways exist for the spread of MLN. The current study was conducted to understand farmers’ maize production practices, their understanding of MLN, and the status of MLN in Kenya. Therefore, a survey of 406 randomly selected farmers was conducted in Bomet, Narok, Kirinyaga, Embu, and Nakuru. To confirm the presence of MLN, maize leaf samples were collected from 18 fields and tested for MCMV and SCMV by molecular techniques. MLN Symptoms observed included chlorotic mottle on leaves, necrosis, and premature plant death. MCMV and SCMV were detected in all the maize growing regions at varying levels of incidence, and severity. Sequence analysis of the partial coat protein genes of randomly selected positive samples of the two viruses showed little variability within the studied isolates and those retrieved from the GenBank. The results indicated that MLN is still prevalent in Kenya with farmers’ planting susceptible varieties.

Microsecond melting and revitrification of cryo samples: protein structure and beam-induced motion.

A novel approach to time-resolved cryo-electron microscopy (cryo-EM) has recently been introduced that involves melting a cryo sample with a laser beam to allow protein dynamics to briefly occur in the liquid, before trapping the particles in their transient configurations by rapidly revitrifying the sample. With a time resolution of just a few microseconds, this approach is notably fast enough to study the domain motions that are typically associated with the activity of proteins but which have previously remained inaccessible. Here, crucial details are added to the characterization of the method. It is shown that single-particle reconstructions of apoferritin and Cowpea chlorotic mottle virus from revitrified samples are indistinguishable from those from conventional samples, demonstrating that melting and revitrification leaves the particles intact and that they do not undergo structural changes within the spatial resolution afforded by the instrument. How rapid revitrification affects the properties of the ice is also characterized, showing that revitrified samples exhibit comparable amounts of beam-induced motion. The results pave the way for microsecond time-resolved studies of the conformational dynamics of proteins and open up new avenues to study the vitrification process and to address beam-induced specimen movement.

Production and characterization of chimeric SARS-CoV-2 antigens based on the capsid protein of cowpea chlorotic mottle virus

The COVID-19 pandemic has highlighted the need for new vaccine platforms to rapidly develop solutions against emerging pathogens. In particular, some plant viruses offer several advantages for developing subunit vaccines, such as high expression rates in E. coli, high immunogenicity and safety, and absence of pre-immunity that could interfere with the vaccine's efficacy. Cowpea chlorotic mottle virus (CCMV) is a model system that has been extensively characterized, with key advantages for its use as an epitope carrier. In the present study, three relevant epitopes from the SARS-CoV-2 Spike protein were genetically inserted into the CCMV CP and expressed in E. coli cultures, resulting in the CCMV1, CCMV2, and CCMV3 chimeras. The recombinant CP mutants were purified from the formed inclusion bodies and refolded, and their immunogenicity as a subunit vaccine was assessed in BALB/c mice. The three mutants are immunogenic as they induce high IgG antibody titers that recognize the recombinant full-length S protein. This study supports the application of CCMV CP as an attractive carrier for the clinical evaluation of vaccine candidates against SARS-CoV-2. Furthermore, it suggests that VLPs assembled from these chimeric proteins could result in antigens with better immunogenicity.

English

Diagnosis of maize lethal necrosis (MLN)-causing viruses is key in MLN surveillance programs and in testing seed for zero tolerance of Maize chlorotic mottle virus (MCMV) in seed lots. This is crucial for MLN management in farmers’ fields and in commercial seed fields. A customized MCMV detection assay that is specific, sensitive, affordable, and portable is therefore important for this task. Reverse Transcriptase–Recombinase Polymerase Amplification (RT-RPA) meets those conditions earlier described. RPA is a rapid isothermal nucleic acid amplification and detection platform that is based on patented Recombinase Polymerase Amplification (RPA) technology. In this study, a real time endpoint analysis and field deployable RT-RPA diagnostic method for the detection of MCMV was developed. RPA primer sets with their complementary probes were designed, synthesized and tested through a series of primer set evaluations to determine the most efficient primer sets. The primer sets targeted the MCMV genome at position 2765-2948 bp (MCMV_gp2 replicase gene). The parameters evaluated were sensitivity, specificity and reproducibility for the assay with remarkable results. The assay discriminated against other maize infecting viruses hence specific to MCMV. The assay takes only 20 min and its detection limit of 10-4 is well comparable to RT-PCR and other molecular based detection assays. MCMV was also detected directly from leaf saps without the nucleic acid extraction step hence suitable for on-farm testing. RPA is a relatively inexpensive technique that requires minimal instrumentation. This assay is therefore suitable for the detection of MCMV in field surveys, routine MCMV testing for phytosanitary measures and in the seed certification procedures.   Key words: Maize lethal necrosis, maize chlorotic mottle virus, diagnostics, recombinase polymerase amplification.

Complete genome sequence of malva-associated soymovirus 1: a novel virus infecting common mallow.

In this work, a novel viral genomic sequence with a gene organization typical of members of the genus Soymovirus was identified using high-throughput sequencing data from common mallow. This species is a vigorous wild weed native to the Mediterranean region, commonly found in borders and edges of cultivated fields, making it a suitable reservoir for plant pests and pathogens. Indeed, plant viruses belonging to different genera have been previously found infecting common malva. This new viral genome consists of a single molecule of circular double-stranded DNA of 8391 base pairs and contains eight open reading frames encoding polymerase, movement, coat, translational transactivator protein typical of caulimoviruses, and four hypothetical proteins. Phylogenetic and pairwise distance analyses showed its close relationship with soybean chlorotic mottle virus. Interestingly, a small intergenic region was detected between ORFs Ib and II. Based on the demarcation criteria of the genus Soymovirus, the new virus, provisionally named malva-associated soymovirus 1, could be a member of a new species Soymovirus masolus. To our knowledge, this is the first report of a soymovirus infecting common mallow.

Delivery of MicroRNAs by plant virus-based nanoparticles to functionally alter the osteogenic differentiation of human mesenchymal stem cells

MicroRNA-26a (miR-26a) has been verified to promote osteogenic differentiation of mesenchymal stem cells in recent years. The main obstacles to its application in bone regeneration are instability in the physiological environment and low efficiency of cellular membrane penetration. To overcome these problems, we constructed a novel plant virus gene delivery system based on Cowpea chlorotic mottle virus (CCMV). By encapsulating miR-26a with purified capsid protein (CP) dimers derived from CCMV, CP-miR-26a (CP26a) virus-like particles (VLPs) were obtained. CP26a retained a structure similar to the native CCMV and protected miR-26a from digestion with its exterior CP. Moreover, CP26a featured similar cellular uptake efficiency, osteogenesis promotion ability, and better biocompatibility compared with Lipofectamine2000-miR-26a (lipo26a), which indicated a promising prospect for CCMV as a novel gene delivery system.

Maize Lethal Necrosis: Impact and Disease Management

The authors summarise and explore maize lethal necrosis (MLN) global impact, its causal viruses, their vectors, and disease management strategies. MLN is a destructive synergistic virus disease of maize caused by maize chlorotic mottle virus (MCMV) in combination with one of several viruses in the Potyviridae family. MLN causes severe chlorosis, necrosis, and eventual plant death, instigating severe yield losses. The causal viruses of MLN are mostly transmitted between plants by arthropod vectors, but they can also be transmitted at low frequency through seed and soil. Effective MLN management approaches include developing and growing maize with improved tolerance, crop rotation, controlling arthropod vector populations, managing disease reservoirs, and reducing disease transmission and spread through seed and soil. Despite the devastating impact of MLN over the past decade, especially in East Africa, tremendous progress has been achieved towards successful disease management. The rapid development and deployment of MLN tolerant maize in East Africa has proven an extremely effective management strategy, despite continuous maize plantings and the extensive presence of "green bridges". Identifying and stacking additional sources of MLN tolerance is desirable for breeding durable resistance. In the U.S., weed and vector management combined with crop rotation has effectively prevented the spread of MLN beyond a few states in the Midwest. However, it is important to consider the potential impact of climate change and the presence of pesticide/Bt resistant MLN insect vectors, which may facilitate greater vector proliferation and virus spread. Continued vigilance geared towards preventing virus or vector introduction to new locations is desirable, especially in tropical climates where multiple growing seasons occur annually. Fortunately, conditions conducive to an MLN epidemic are complex, requiring the presence of multiple maize infecting viruses and their respective vectors. Thus, several combinations of the disease management strategies discussed above are effective at managing the disease.

Molecular analysis of grapevine Pinot gris virus and its association with grapevine leaf mottling and deformation on ‘Vermentino’ grapevines in Sardinia

In 2017–2018, grapevines of cultivar ‘Vermentino’ infected with grapevine Pinot gris virus (GPGV) in Sardinia, Italy, exhibited leaf symptoms of mosaic, chlorotic mottling, and curling, and stunted shoots. Disease incidence assessed in 2018 was greater (67%, 103 symptomatic plants out of 153 monitored) than in 2017 (26%, 40 of 153 plants). All symptomatic samples tested by RT-PCR were positive for GPGV in both years, while 70% (53 of 76) of the asymptomatic samples in 2017, and 42% (19 of 45) in 2018, were also positive for GPGV. Characterizing six GPGV isolates from ‘Vermentino’ by RT-PCR and sequencing of a genomic fragment covering the movement and coat protein genes showed high conservation at the nucleotide level (98.7% to 100.0%) among Sardinian isolates and isolates for which sequence information is available in GenBank. Phylogenetic analysis indicated that most Sardinian GPGV isolates grouped with other European isolates. This is the first characterization of GPGV in a Sardinian vineyard.

Maize miR167-ARF3/30-polyamine oxidase 1 module-regulated H2O2 production confers resistance to maize chlorotic mottle virus.

Maize chlorotic mottle virus (MCMV) is the key pathogen causing maize lethal necrosis (MLN). Due to the sharply increased incidence of MLN in many countries, there is an urgent need to identify resistant lines and uncover the underlying resistance mechanism. Here, we showed that the abundance of maize (Zea mays) microR167 (Zma-miR167) positively modulates the degree of resistance to MCMV. Zma-miR167 directly targets Auxin Response Factor3 (ZmARF3) and ZmARF30, both of which negatively regulate resistance to MCMV. RNA-sequencing coupled with gene expression assays revealed that both ZmARF3 and ZmARF30 directly bind the promoter of Polyamine Oxidase 1 (ZmPAO1) and activate its expression. Knockdown or inhibition of enzymatic activity of ZmPAO1 suppressed MCMV infection. Nevertheless, MCMV-encoded p31 protein directly targets ZmPAO1 and enhances the enzyme activity to counteract Zma-miR167-mediated defense to some degree. We uncovered a role of the Zma-miR167-ZmARF3/30 module for restricting MCMV infection by regulating ZmPAO1 expression, while MCMV employs p31 to counteract this defense.

The Importance of Agroforestry Systems for Mitigation of Climate Change in Tropical Africa

Plant virus diseases are serious constraints to the productivity and profitability of a wide range of crops. Epidemics of existing plant virus diseases and the emergence of novel virus diseases have become a serious threat to subsistence and commercial agriculture. The knowledge of virus transmission and its survival helps to understand how the disease transmits from infected plant to healthy, where it reserved, and this will lead to identify the most important variables and focus efforts to develop sustainable management strategies. Maize chlorotic mottle virus (MCMV) is transmitted from location to location, and from plant to plant through various mechanisms (mechanically, seed, insect vectors, and soil) and many kinds of wild grass and cultivated crops, maize residue are used as its reservoirs. Different weed species and cultivated plants used as alternate hosts, and soil and seed transmissibility of MCMV are epidemiologically important and contribute to maintaining virus inoculum available in the absence of maize in the field and increase the chances of continuing its survival. Integrated disease management approach, regular field monitoring, assessment of virus symptoms, and rouging-out diseased plants are recommended to prevent further spread by insect vectors. Apart from this, because the disease is still widespread in various countries, intensive MCMV recruitment, combined with integrated disease management, requires ongoing practice in countries where MCMV is prevalent and in those countries that have not yet reported MCMV. Keywords : Integrated management; Insect vector; plant residue; Soil transmission; Zea mays DOI: 10.7176/JNSR/13-5-02 Publication date: March 31 st 2021

Maize chlorotic mottle virus

Maize chlorotic mottle virus

Soybean chlorotic mottle virus

This datasheet on Soybean chlorotic mottle virus covers Identity, Distribution, Hosts/Species Affected.

Registration of the maize synthetic population OhMCMV‐1

AbstractMaize lethal necrosis (MLN) is a devastating virus disease of maize, induced by co‐infection by Maize chlorotic mottle virus (MCMV) and one of several potyviruses. The maize synthetic population OhMCMV‐1 (Cycle‐1 [C1]) (Reg. no. GP‐623, PI 699306) was developed and released by the USDA‐ARS Corn, Soybean, and Wheat Quality Research Unit as a germplasm resource for improved MLN, MCMV, and Sugarcane mosaic virus (SCMV) resistance. The population has undergone one complete cycle of S1 recurrent selection for resistance to MCMV. Cycle‐1 S1 lines were significantly more resistant to MLN, MCMV, and SCMV than Cycle‐0 S1 lines. The elite virus resistance present within OhMCMV‐1 (C1) indicates this population has strong utility for developing new breeding lines, hybrids, and varieties and for helping to mitigate the economic impact of MLN.

Occurrence of maize yellow mosaic virus and evidence of co-infection with maize lethal necrosis viruses in Bomet County, Kenya

Maize Lethal Necrosis (MLN) disease is caused by synergistic interaction between maize chlorotic mottle virus (MCMV) and sugarcane mosaic virus (SCMV). However, some East African countries have detected maize infecting polerovirus named maize yellow mosaic virus (MaYMV) also known as maize yellow dwarf virus (MYDV-RMV) co-infecting maize with MLN viruses. Maize yellow dwarf virus occurrence and distribution in different parts of Kenya are not yet elucidated. This study aimed to establish the occurrence of MaYMV in maize and sorghum in Bomet County, MLN hotspot region in Kenya. Maize (n=90) and sorghum (n=19) samples were collected from East and Central sub-counties of Bomet County in 2019/2020. Reverse transcription-polymerase chain reaction (RT-PCR) protocol was developed and optimized for screening the samples using specific primers. Amplicons of 600, 250 and 169 bp were generated for MaYMV, MCMV and SCMV, respectively. The analysis revealed 56% (62/109) of the samples tested positive for MaYMV co-infecting maize with MLN viruses. Sanger sequencing of representative samples confirmed the presence of MaYMV. BLASTN analysis showed 95-100% sequence identity to MaYMV/MYDV-RMV hence confirmed the occurrence of MaYMV infecting maize and sorghum in Bomet County whose impacts is a potential threat to food security. Key words: Occurrence, co-infection, maize lethal necrosis, maize yellow mosaic virus, maize chlorotic mottle virus, sugarcane mosaic virus.

Construction of an Infectious Clone of the Badnavirus Cacao Swollen Shoot Ghana M Virus and Infectivity by Gene Gun- and Agrobacterium-Mediated Inoculation

Cacao swollen shoot disease (CSSD) is a damaging disease of Theobroma cacao L. associated with infection by a group of poorly characterized badnaviral species. To establish causality and characterize the symptomatology associated with infection by the badnavirus cacao swollen shoot Ghana M virus (CSSGMV), an infectious clone (1.3-mer) was constructed and used to inoculated cacao “Amelonado” seedlings by biolistic inoculation (BI; n = 18) and agroinoculation (AI; n = 15). Newly expanded leaves of BI (10/18) and AI (12/15) plants developed foliar mosaic and curling symptoms 30-days post inoculation (dpi), with chlorotic mottling and necrotic crinkling being evident by 90 dpi. By 120 dpi, three of 15 AI plants exhibited characteristic stem-swelling. Viral infection was verified by PCR-amplification and sequencing of a 1068 bp fragment of the CSSGMV ORF3 from newly expanding leaves 60 dpi. The PCR results indicated that 14 of 18 and 15 of 15 BI and AI plants, respectively, were systemically infected. The complete CSSGMV genome sequence was determined, by Illumina sequencing, from representative AI and BI plants and shared >99.5% pairwise nucleotide identity with CSSGMV-Nig9 (GenBank Accession No. MH785299). Based on the development of characteristic CSSD symptoms and recovery of partial and complete genome sequences of CSSGMV-Nig9 from systemically infected cacao plants, Koch's postulates have been fulfilled.

Characterization of a Novel Emaravirus Affecting Ash Species (Fraxinus spp.) in Europe

We identified a novel virus in diseased European ash (Fraxinus excelsior) and manna ash (F. ornus) trees exhibiting chlorotic ringspots, mottle and leaf deformation such as curling and shoestring symptoms. High-throughput sequencing (HTS, Illumina RNASeq) of total RNA isolated from diseased leaf material in combination with RT-PCR-based amplification techniques and Sanger sequencing determined five complete genome segments, each encoding a single open reading frame. Sequence analyses of RNA1–RNA5 revealed a genome organization typical for emaraviruses, i.e., (i) conserved and complementary terminal 5′ and 3′ termini of each genome segment (ii) proteins showing significant homologies to the RNA-dependent RNA polymerase (RdRP) encoded by RNA1, the glycoprotein precursor (GPP) encoded by RNA2, the viral nucleocapsid protein (N, RNA3), the movement protein (MP, RNA4), and a protein of 26 kDA (P26, RNA5) highly similar to proteins of unknown function encoded by other emaraviruses. Furthermore, we identified spherical particles (double-membrane bodies, DMB) of different sizes (70–80 nm in diameter) which are typical for emaraviruses exclusively in virus-infected leaf tissue exhibiting mottle and leaf deformation. Sequence comparison and phylogenetic analyses confirmed the identified novel virus as a new member of the genus Emaravirus. We established a species-specific RT-PCR detection protocol and could associate the observed disease symptoms with the infection of the novel emaravirus in F. excelsior and F. ornus. Therefore, we propose the name ash shoestring-associated emaravirus (ASaV). Investigation of ASaV-infected sample trees originating from different locations in Switzerland, Germany, Italy and Sweden provided a wide geographical distribution of the virus in affected ash species. To our knowledge, this is the first confirmation of an emaravirus affecting ash tree species with shoestring symptoms of leaves in Europe.

Maize Chlorotic Mottle Virus: Distribution, Alternative Hosts, Transmission Mechanisms and Management Options

Plant virus diseases are serious constraints to the productivity and profitability of a wide range of crops. Epidemics of existing plant virus diseases and the emergence of novel virus diseases have become a serious threat to subsistence and commercial agriculture. The knowledge of virus transmission and its survival helps to understand how the disease transmits from infected plant to healthy, where it reserved, and this will lead to identify the most important variables and focus efforts to develop sustainable management strategies. Maize chlorotic mottle virus (MCMV) is transmitted from location to location, and from plant to plant through various mechanisms (mechanically, seed, insect vectors, and soil) and many wild types of grass and cultivated crops, MCMV infected maize residue are used as its reservoirs. Different weed species and cultivated plants used as alternate hosts, and soil and seed transmissibility of MCMV are epidemiologically important and contribute to maintaining virus inoculum available in the absence of maize in the field and increase the chances of continuing its survival. Integrated disease management approach, regular field monitoring, assessment of virus symptoms, and rouging-out diseased plants are recommended to prevent further spread by insect vectors. Apart from this, because the disease is still widespread in various countries, intensive MCMV recruitment, combined with integrated disease management, requires ongoing practice in countries where MCMV is prevalent and in those countries that have not yet reported MCMV. Keywords : Integrated management; Insect vector; plant residue; Soil transmission; Zea mays DOI: 10.7176/JBAH/11-19-04 Publication date: October 31 st 2021

First report of Cucurbit chlorotic yellows virus infecting cantaloupe (Cucumis melo L.) in Texas.

Texas is a major producer of cucurbits such as cantaloupe (Cucumis melo L.), but outbreaks of virus-like diseases often adversely affect yields. Little is known about the identity of the causal or associated viruses. During studies conducted in fall 2020 to explore the virome of cucurbit fields in Texas, a commercial cantaloupe field (~4.1 ha) in Cameron County was observed with virus-like symptoms of interveinal chlorotic mottle and foliar chlorosis and disease incidence was estimated at 100%. Virus-like symptoms including mosaic and leaf curl were also observed in six additional fields across five south and central Texas counties of Atascosa, Hidalgo, Fort Bend, Frio, and Wharton. Forty-six plants, which included 32 symptomatic and 14 non-symptomatic, were sampled from these fields for virus diagnosis and each sample was subjected to total nucleic acid extraction according to Dellaporta et. al. (1983). Initially, equal amounts of nucleic acids from 14 symptomatic plants (two/field) were pooled into one composite sample for preliminary diagnosis by high throughput sequencing (HTS). The cDNA library obtained from the composite sample with a TruSeq Stranded Total RNA with Ribo-Zero Plant Kit (Illumina) was sequenced on the Illumina NextSeq 500 platform, generating ~26.3 M single-end HTS reads (75 nucleotides [nt] each). Analyses of the reads according to Al Rwahnih et al. (2018) revealed several virus-like contigs; among them 23 contigs (206 to 741 nt) shared 98 to 100% nt identities to isolates of cucurbit chlorotic yellows virus (CCYV), genus Crinivirus, family Closteroviridae. Three pairs of CCYV-specific primers were designed from the HTS contigs with primers CCYV-v1330: 5'-AGTCCCTTACCCTGAGATGAA/CCYV-c2369: 5'-CGGAGCATTCGACAACTGAATA targeting ~1 kb fragment of the ORF1a (RNA1), primers CCYV-v4881: 5'-ATAAGGCGGCGACCTAATC/CCYV-c5736: 5'-GATCACTTGACCATCTCCTTCT targeting a ~0.9 kb fragment encompassing the coat protein (CP) cistron of CCYV (RNA2), and primers CCYV-v6362: 5'-CACCTCTTCCAGAACCAGTTAAA/CCYV-c7423: 5'-TGGGAACAACTTATTTCTCCTAGC targeting ~1 kb spanning partial minor coat protein (CPm) and p26 sequences (RNA2). Total nucleic acid extracts of each of the 46 samples from the seven fields were tested by two-step reverse transcription polymerase chain reaction using all three CCYV-specific primer pairs and they yielded amplicons of expected sizes from all five symptomatic cantaloupe samples from the Cameron County field and one additional symptomatic butternut squash sample from a field in Hidalgo County. The DNA bands from three randomly chosen cantaloupe samples were cloned and sequenced as previously described (Oke et al. 2020). In pairwise comparisons, the obtained 1,040 nt ORF1a (MW584332-334), 753 nt complete CP (MW584335-337), and 1,062 nt CPm/p26 (MW584338-340) gene specific sequences from the three samples shared 100% nt identity with each other, and 99-100% nt identities with corresponding RNA1 (AB523788) and RNA2 (AB523788) sequences of the exemplar isolate of CCYV. This is the first report of CCYV in Texas, thus expanding the current geographical range of the virus in the U.S. that includes California (Wintermantel et al. 2019) and Georgia (Kavalappara et al. 2021). The abundance of whiteflies of the Bemisia tabaci species complex in south Texas and other major U.S. cucurbit production areas presents additional challenges to virus disease management.

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. Results demonstrated that MaYMV symptoms included stunting as well as leaf reddening in single and mixed infections. MaYMV did not recapitulate MLN synergistic disease in double infections in which either MCMV or SCMV was missing (MaYMV + MCMV or MaYMV + SCMV), but did significantly enhance stunting in mixed infections and suppressed titers of both MCMV and SCMV in double infections. Interestingly, MaYMV strongly suppressed the SCMV-induced titer increase of MCMV in triple infections, but MLN symptoms still occurred with the reduced MCMV titer. These data indicate the potential disease impact of this newly discovered ubiquitous maize virus, alone and in the context of MLN.