On August 9, 2019, USDA-APHIS published a list of “Native and Naturalized Plant Pests Permitted by Regulation”. Interstate movement of these plant pests is no longer federally regulated within the 48 contiguous United States. There are 49 plant pathogens (bacteria, fungi, viruses, and nematodes) on this list. California may choose to continue to regulate movement of some or all these pathogens into and within the state. In order to assess the needs and potential requirements to issue a state permit, a formal risk analysis for Zucchini yellow mosaic virus (ZYMV) is given herein and a permanent pest rating is proposed.

宮古・八重山群島のカボチャから分離した Zucchini Yellow Mosaic Virus

Cucumber mosaic virus (CMV, Bromoviridae: Cucummovirus), one of the most widespread plant viruses with several hosts, causes huge losses in yield quality and quantity. The occurrence of various CMV strains and high genetic diversity within the virus complicate its management. We describe the population structure of CMV in Nigeria using partial RNA1 and RNA3 gene sequences from three natural hosts: pepper (Capsicum annuum), tomato (Solanum lycopersicum), and watermelon (Citrullus lanatus). One hundred and six leaf samples were obtained from 16 locations across Nigeria, and specific primers were used to amplify the two gene fragments using PCR. Twenty-four samples tested positive for CMV using RNA1 primers, and amplicons were sequenced from 12 isolates, revealing 82.94–99.80% nucleotide and 85.42–100% amino acid sequence similarities within the population. The partial RNA3 fragment, corresponding to the complete coat protein (CP) gene, was sequenced from seven isolates, with 95.79–97.90% and 98.62–100% nucleotide and amino acid intrapopulation similarities, respectively. The isolates belonged to subgroup IB and formed distinct phylogenetic clusters in both gene sets, indicating putative novel strains. Recombination signals, supported by phylogenetic inferences, were detected within the RNA1 dataset (P ≤ 0.05) and identified a recombinant isolate within the Nigerian sequences. No recombination was detected within the CP genes. Population genetics parameters established high diversity within the Nigerian population compared to other isolates worldwide, while selection pressure estimates revealed the existence of negative selection in both gene sets. Although CMV subgroup IB strains were postulated to originate from Asia, this study reveals their prevalence across several hosts from different locations in Nigeria. To our knowledge, this is the first comprehensive description of a recombinant CMV subgroup IB isolate from West Africa, which has implications for its robust detection and overall management.

/pdf/genetic-structure-of-cucumber-mosaic-virus-from-natural-nh6va2wp.pdf

Genetic Structure of Cucumber Mosaic Virus From Natural Hosts in Nigeria Reveals High Diversity and Occurrence of Putative Novel Recombinant Strains

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.

/pdf/occurrence-distribution-and-identification-of-viruses-4ehcvcktrc.pdf

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

The effectiveness of pest and disease management in crops relies on knowledge about their presence and distribution in crop-producing areas. Aphids and whiteflies are among the main threats to vegetable crops since these hemipterans feed on plants, causing severe damage, and are also able to transmit a large number of devastating plant viral diseases. In particular, the widespread occurrence of aphid-transmitted viruses in cucurbit crops, along with the lack of effective control measures, makes surveillance programs and virus epidemiology necessary for providing sound advice and further integration into the management strategies that can ensure sustainable food production. This review describes the current presence and distribution of aphid-transmitted viruses in cucurbits in Spain, providing valuable epidemiological information, including symptom expressions of virus-infected plants for further surveillance and viral detection. We also provide an overview of the current measures for virus infection prevention and control strategies in cucurbits and indicate the need for further research and innovative strategies against aphid pests and their associated viral diseases.

/pdf/occurrence-distribution-and-management-of-aphid-transmitted-3dddp867.pdf

Occurrence, Distribution, and Management of Aphid-Transmitted Viruses in Cucurbits in Spain

Cucumber mosaic virus management: Conventional, indigenous technical knowledge and molecular approaches

Trichosanthes cucumerina L is a tropical or subtropical fruit bearing crop of the Cucurbitaceae family. Field survey during 2020 planting season in Akamkpa, Southern Cross River State, Nigeria revealed widespread virus infection of the crop. Symptoms observed included severe leaf malformation/reduction and rugosity. This research was therefore aimed at identifying viruses infecting Trichosanthes cucumerina in this location. Infected leaf samples were collected and virus maintained on young seedlings of T. cucumerina in the Botanical Garden of University of Calabar, Nigeria. Diagnostic tools included ACP-ELISA and gene sequence analysis. The ELISA result revealed two viruses belonging to the genus Cucumovirus and Potyvirus. The identity of the viruses were determined after virus sequences were compared with other viruses available in the GenBank of National Centre for Biotechnology Information (NCBI) using the basic local alignment search tool (BLASTn). The result revealed the Cucumovirus to be Cucumber mosaic virus (CMV) while the Potyvirus was revealed to be Potato virus Y (PVY). This is the first report of mixed virus infection on Trichosanthes cucumerina in Nigeria. Original Research Article Eyong et al.; AJAAR, 15(2): 53-58, 2021; Article no.AJAAR.67945 54

/pdf/identification-of-mixed-virus-infection-on-trichosanthes-1fsbirxnck.pdf

Identification of Mixed Virus Infection on Trichosanthes cucumerina L. in Akamkpa, Southern Cross River State, Nigeria

Cucumber mosaic virus (CMV) is one of the most important viral pathogens infecting a wide range of plant species in Nigeria. Mosaic and mottle symptoms were observed on Lagenaria siceraria L. in Adim Southern-Nigeria in 2018 and the infected leaves collected for investigation. This research was aimed at characterising the virus responsible for this infection with a view to identifying it. Antigen coated plate (ACP) enzyme linked-immunosorbent assay (ELISA) and gene sequencing were employed methods in the characterisation process. The Amplified Complementary Deoxyribonucleic Acid (cDNA) was cloned and the nucleotide sequence was determined. Result of serology revealed that the virus belonged to the genus Cucumovirus while the gene sequence Original Research Article Eyong et al.; ARRB, 35(4): 45-52, 2020; Article no.ARRB.54366 46 obtained when compared to known virus sequences present in the GenBank using the Basic Local Alignment Search Tool (BLAST) program available at National Centre for Biotechnology Information (NCBI) revealed 97% sequence homologue with Cucumber mosaic virus confirming it as Cucumber mosaic virus. This is the first report of CMV infecting L. siceraria in Nigeria. I recommend further studies on insect and host range test of this virus be carried on.

/pdf/serological-and-molecular-characterisation-of-cucumber-3ktg6dpors.pdf

Serological and Molecular Characterisation of Cucumber mosaic virus Infecting Lagenaria siceraria L. in Adim, Biase L.G.A., Cross River State, Nigeria

Leaf samples of Ocimum gratissimum (L.) exhibiting vein banding, mosaic and chlorotic spots were collected randomly from the field. The symptomatic samples reacted positively to specific CMV antibody in antigen coated plate enzyme linked immunosorbent assay and to confirm the presence of CMV, RT-PCR was performed using CMV-specific primers that amplify a 519 bp region from the viral coat protein gene. The expected amplicon shared homology of 97.06% with a Nigerian isolate MH178110. Phylogenetic tree constructed revealed the isolate in close association with CMV strains belonging to subgroup II. This is the first molecular evidence of CMV in O. gratissimum in Nigeria and adds to the list of natural host for the virus.

First report of Cucumber mosaic virus infecting Ocimum gratissimum (L.) in Calabar, Cross River State, Nigeria

Temple tree (Plumeria rubra) is a cosmopolitan ornamental flowering and an avenue tree. Generally, Plumeria sp. is affected by several diseases, among them rust caused by Coleosporium plumeriae was found infecting the temple trees in Bengaluru, Karnataka, India with the severity of 80-100 per cent in the early June till end of August 2016-17. Initially, numerous orange coloured rusty pustules were seen on abaxial leaf and these pustules covered the entire leaf causing inward rolling of leaves, necrosis, senescence and finally leaf abscission. Microscopic observation of the rust pustules revealed the presence of golden pale yellow coloured uredospores that varied from globose to ellipsoidal in shape, ranging from 20-40 x 16-28 mm in size, borne on erumpent uredinia and no other spore stages were observed. Molecular identification of this pathogen (Indian isolate) through ITS rDNA region amplification, sequencing and phylogenetic analysis revealed 99 % sequence homology with the China isolate (Accession no. KF879087.1). ITS rDNA region partial sequence of the pathogen was deposited in NCBI, GenBank with accession no. MH656772.

E. E. Ekpiken

Papers

Identification of Mixed Virus Infection on Trichosanthes cucumerina L. in Akamkpa, Southern Cross River State, Nigeria

Serological and Molecular Characterisation of Cucumber mosaic virus Infecting Lagenaria siceraria L. in Adim, Biase L.G.A., Cross River State, Nigeria

First report of Cucumber mosaic virus infecting Ocimum gratissimum (L.) in Calabar, Cross River State, Nigeria

Mixed infection of a potyvirus and cucumber mosaic virus on Ocimum gratissimumin Okoyong and Boje, Cross River State, Nigeria