Molecular Characterization of Virus Infecting Momordica charantia Linn and the Application of Trichoderma viride as Biocontrol Agent in Baccocco Cross River State, Nigeria

Momordica charantia Linn, commonly called bitter-melon or ampalaya, is a vigorous, tendril-bearing, frost tender, annual vine of the cucurbitacae family reported to play significant role in health and nutrition. Chlorotic spot symptoms were observed on this plant during a visit to some Gardens in Baccocco Cross River State, Nigeria in 2021. The aim of this study was to identify the virus infecting this plant and investigate the ability of Trichoderma viride to control the virus. Infected leaf samples of M. charantia were collected and maintained on young seedlings of cucumber through mechanical inoculation which was further used to test the ability of Trichoderma viride as biocontrol agent, the sample was further tested against RT-PCR. Result obtained from Gene sequence analysis revealed 87 % nucleotide sequence identity with Morroccan watermelon mosaic virus. This is the first report of MWMV infecting M. charantia in Nigeria. The result further showed that Trichoderma viride was very effective in the control of virus the pathogen.

Coinfection of Cotton Plants with Watermelon Mosaic Virus and a Novel Polerovirus in China

Cotton is the most important fiber crop worldwide. To determine the presence of viruses in cotton plants showing leaf roll and vein yellowing symptoms in Henan Province of China, a small RNA-based deep sequencing approach was performed. Analysis of the de novo-assembled contigs followed by reverse transcription PCR allowed the reconstruction of watermelon mosaic virus and an unknown virus. The genome of the unknown virus was determined to be 5870 nucleotides in length, and has a genomic organization with characteristic features of previously reported poleroviruses. Sequence analysis revealed that the virus was closely related to, but significantly different from, cotton leafroll dwarf virus, a polerovirus of the family Solemoviridae. This virus had less than 90% amino acid sequence identity in the products of both ORF0 and ORF1. According to the polerovirus species demarcation criteria set by the International Committee on Taxonomy of Viruses, this virus should be assigned to a new polerovirus species, for which we propose the name “cotton leaf roll virus”.

Genetic Variability and Evidence of a New Subgroup in Watermelon Mosaic Virus Isolates

Watermelon mosaic virus (WMV) is one of the important Potyviruses that infect cucurbits worldwide. To better understand the population structure of WMV in the United States (U.S.), 57 isolates were collected from cucurbit fields located in nine southern states. The complete coat protein gene of all WMV isolates was cloned, sequenced and compared with 89 reported WMV isolates. The nucleotide and amino acid sequence identities among the U.S. WMV isolates ranged from 88.9 to 99.7% and from 91.5 to 100%, respectively. Phylogenetic analysis revealed that all the U.S. WMV isolates irrespective of their geographic origin or hosts belonged to Group 3. However, the fifty-seven isolates made three clusters in G3, where two clusters were similar to previously reported subgroups EM1 and EM2, and the third cluster, containing nine WMV isolates, formed a distinct subgroup named EM5 in this study. The ratio of non-synonymous to synonymous nucleotide substitution was low indicating the occurrence of negative purifying selection in the CP gene of WMV. Phylogenetic analysis of selected 37 complete genome sequences of WMV isolates also supported the above major grouping. Recombination analysis in the CP genes confirmed various recombinant events, indicating that purifying selection and recombination are the two dominant forces for the evolution of WMV isolates in the U.S.

Occurrence of a novel strain of Moroccan watermelon mosaic virus infecting pumpkins in Kenya

The potyvirus Moroccan watermelon mosaic virus (MWMV) naturally infects and severely threatens production of cucurbits and papaya. In this study, we identified and characterized MWMV isolated from pumpkin (Cucurbita moschata) intercropped with MWMV-infected papaya plants through next generation and Sanger sequencing approaches. Complete MWMV genome sequences were obtained from two pumpkin samples through NGS and validated using Sanger sequencing. The isolates share 83.4-83.7 % nucleotide (nt) and 92.3-95.1 % amino acid (aa) sequence identities in the coat protein and 79.5-79.9 % nt and 89.2-89.7 % aa identities in the polyprotein with papaya isolates of MWMV. Phylogenetic analysis using complete polyprotein nt sequences revealed the clustering of both pumpkin isolates of MWMV with corresponding sequences of cucurbit isolates of the virus from other parts of Africa and the Mediterranean regions, distinct from a clade formed by papaya isolates. Through sap inoculation, a pumpkin isolate of MWMV was pathogenic on zucchini (Cucurbita pepo), watermelon (Citrullus lanatus), and cucumber (Cucumis sativus), but not on papaya. Conversely, the papaya isolate of MWMV was non-pathogenic on pumpkin, watermelon, and cucumber, but infected zucchini. The results suggest occurrence of two strains of MWMV in Kenya having different biological characteristics associated with the host specificity.

Occurrence, Distribution and Identification of Viruses Infecting Some Cucurbits Across Major Cucurbit-Growing Areas in Cross River State, Nigeria

Cucurbits are group of plants which belonged in the Cucurbitaceae family and constitute one of the most important vegetables for human consumption throughout the world. A survey conducted between January to March 2021 across major cucurbit-growing area in Cross River State revealed wide spread virus infection of these crops, surveyed plants showed mosaic, mottle and leaf deformation symptoms. This research was aimed at identifying viruses infecting some cucurbits in the study areas. Twenty four samples showing virus like symptoms were collected and tested against ACP-ELISA and RT-PCR. Result obtained from ACP-ELISA showed that 20 out of 24 samples collected tested positive to universal potyvirus antisera, the gene sequence analysis revealed that samples were predominantly infected with Algerian watermelon mosaic virus representing 40% of total viruses detected followed by Morroccan watermelon mosaic virus representing 15% of total viruses detected followed by Papaya ringspot virus, Zucchini tigre mosaic virus, Watermelon mosaic virus and Soybean mosaic virus representing 10% each for total viruses detected and finally Potato virus Y representing 5% of total virus detected. This survey is an accurate and timely detection and will form the basis for mitigating yield losses resulting from virus infection on cucurbits. This is the first report of wide scale detection of viruses infecting cucurbits in Nigeria.

Multiple aromatic amino acids are involved in potyvirus movement by forming π-stackings to maintain coat protein accumulation

Coat protein (CP) is required for potyviruses to move and establish a systemic infection in plants. π-stackings formed by aromatic residues play critical roles in maintaining protein stability and functions. As we know, many aromatic residues located in the core region of potyvirus CPs are conserved. However, their roles in potyvirus infection remain largely unknown. Here, through analysis of the three-dimensional model of the tobacco vein banding mosaic virus (TVBMV; genus Potyvirus) CP, 16 aromatic residues were predicated to form π-stackings. The results of transient expression experiments demonstrated that deletion of any of these 16 aromatic residues reduced CP accumulation. Infectivity assays showed that deletion of any of these aromatic residues in the TVBMV infectious clone abolished cell-to-cell movement and reduced replication of the virus. Substitution of Y105 and Y147 individually with non-aromatic residues alanine or glycine reduced CP accumulation, virus replication, and abolished the ability of TVBMV to move intercellularly, while substitution of these two residues individually with aromatic residues phenylalanine or tryptophan, had no or little effect on CP accumulation and TVBMV systemic movement and replication. Similar results were obtained from the CP mutants of watermelon mosaic virus (WMV, genus Potyvirus). Taken together, our results demonstrate that multiple aromatic residues in CP are involved in potyvirus movement by forming π-stackings to maintain CP accumulation.

SYSTEMATIC LITERATURE REVIEW (SLR): DISEASE DETECTION IN MELONS USING DIGITAL IMAGE PROCESSING

Systematic Literature Review (SLR) is a technique used in this study which is used to study techniques for identifying leaf diseases using digital images as a basis for obtaining an understanding of disease identification techniques in melon leaves with digital images. Based on data from the Central Statistics Agency for the last 3 years from 2017-2019, melon production has increased considerably. Melon production data in 2017 was 92.43 tons, in 2018 was 118,708 and in 2019, overall melon production was 122,105 tons collected from 34 provinces in Indonesia. The problem that is often encountered in melon cultivation is the presence of plant pests that can harm and not maximize the yields of farmers. Several viruses cause mosaic disease that infects Cucurbitaceae plants, namely Cucumber aphid borne yellows virus (CABYV), Cucumber green mottle mosaic virus (CGMMV), Cucumber mosaic virus (CMV), Papaya ringspot virus (PRSV), Squash mosaic virus (SqMV), Squash leaf curl virus (SLCV), Watermelon mosaic virus (WMV). Information technology has now developed to be able to manage digital image data to identify problems faced by farmers. Several classification methods that can be used to answer problems include SVM, Artificial Neural Network, Decision Tree, Convolutional Neural Network.

Emerging strains of watermelon mosaic virus in Southeastern France: model-based estimation of the dates and places of introduction

Where and when alien organisms are successfully introduced are central questions to elucidate biotic and abiotic conditions favorable to the introduction, establishment and spread of invasive species. We propose a modelling framework to analyze multiple introductions by several invasive genotypes or genetic variants, in competition with a resident population, when observations provide knowledge on the relative proportions of each variant at some dates and places. This framework is based on a mechanistic-statistical model coupling a reaction–diffusion model with a probabilistic observation model. We apply it to a spatio-temporal dataset reporting the relative proportions of five genetic variants of watermelon mosaic virus (WMV, genus Potyvirus, family Potyviridae) in infections of commercial cucurbit fields. Despite the parsimonious nature of the model, it succeeds in fitting the data well and provides an estimation of the dates and places of successful introduction of each emerging variant as well as a reconstruction of the dynamics of each variant since its introduction.

The P1 Protein of Watermelon mosaic virus Compromises the Activity as RNA Silencing Suppressor of the P25 Protein of Cucurbit yellow stunting disorder virus

Mixed viral infections in plants involving a potyvirus and other unrelated virus often result in synergistic effects, with significant increases in accumulation of the non-potyvirus partner, as in the case of melon plants infected by the potyvirus Watermelon mosaic virus (WMV) and the crinivirus Cucurbit yellow stunting disorder virus (CYSDV). To further explore the synergistic interaction between these two viruses, the activity of RNA silencing suppressors (RSSs) was addressed in transiently co-expressed combinations of heterologous viral products in Nicotiana benthamiana leaves. While the strong RSS activity of WMV Helper Component Proteinase (HCPro) was unaltered, including no evident additive effects observed when co-expressed with the weaker CYSDV P25, an unexpected negative effect of WMV P1 was found on the RSS activity of P25. Analysis of protein expression during the assays showed that the amount of P25 was not reduced when co-expressed with P1. The detrimental action of P1 on the activity of P25 was dose-dependent, and the subcellular localization of fluorescently labeled variants of P1 and P25 when transiently co-expressed showed coincidences both in nucleus and cytoplasm. Also, immunoprecipitation experiments showed interaction of tagged versions of the two proteins. This novel interaction, not previously described in other combinations of potyviruses and criniviruses, might play a role in modulating the complexities of the response to multiple viral infections in susceptible plants.