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Cowpea plants expressing virus-like symptom similar to AMV infected potato plants from the surveyed field
Source publication
Alfalfa mosaic virus (AMV, family Bromoviridae, genus Alfamovirus) has an extensive host range. The reports of AMV available in India were dated far back as 1979 and 1981 found in alfalfa and brinjal crops respectively. In January 2019, field surveys were conducted for viral diseases infecting potato in Sonitpur and Jorhat districts of Assam state...
Context in source publication
Context 1
... potato viral diseases on the leaves in almost 25% of the plants found in farmer's field. Also, most fields visited are either having potato grown solely or the combination of potato-tomato, potatocowpea or potato-pepper. In an intercrop field, similar symptom expressed on potato was also expressed on intercrop plants especially on cowpea plants (Fig. 2). The potato cultivars grown were recorded as local landraces (small table potato from Jorhat), Kufri Himalini, Kufri Pukhraj and Kufri Jyoti (recommended potato cultivars from ...
Citations
... The AMV host range includes more than 600 species from 70 families. Although most of them are herbaceous plants, such as pepper (Capsicum annum L.), celery (Apium graveolens L.), bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), potato (Solanum tuberosum L.), alfalfa (Medicago sativa L.) and eggplant (Solanum melongena L.), AMV can also infect woody plant species (e.g., Chinese wisteria (Wisteria sinensis) tree) [5][6][7][8]. Recently, in Italy, AMV was first detected in the chayote plant (Sechium edule), which is a climbing cucurbit [9]. ...
Background
Alfalfa mosaic virus (AMV) is an important virus affecting many vegetable crops in Egypt. In this study, virus isolates were collected from naturally infected potato, tomato, alfalfa and clover plants that showed suspected symptoms of AMV in different locations of Beheira and Alexandria governorates during the 2019–2020 growing season. The relative incidence of the virus ranged from 11–25% based on visual observations of symptoms and ELISA testing. A total of 41 samples were tested by ELISA using polyclonal antisera for AMV. Four AMV isolates collected from different host plants, named AM1 from potato, AM2 from tomato, AM3 from alfalfa and AM4 from alfalfa, were maintained on Nicotiana glutinosa plants for further characterization of AMV.
Results
Electron micrographs of the purified viral preparation showed spheroidal particles with a diameter of 18 nm and three bacilliform particles with lengths of roughly 55, 68, and 110 nm and diameters identical to those of the spheroidal particles. The CP gene sequence comparisons of four AMV isolates (AM1, AM2, AM3 and AM4) showed the highest nucleotide identity of 99.7% with the Gomchi isolate from South Korea infecting Gomchi (Ligularia fischeri) plants. Phylogenetic analysis showed that the present isolates were grouped together into a distinct separate clade (GPI) along with the Gomchi isolate from South Korea. Similarly, the deduced amino acid sequence comparisons of Egyptian AMV isolates revealed that amino acids Q²⁹, S³⁰, T³⁴, V⁹² and V¹⁷⁵ were conserved among the Egyptian isolates in GPI.
Conclusion
The present study found strong evolutionary evidence for the genetic diversity of AMV isolates by the identification of potential recombination events involving parents from GPI and GPII lineages. Additionally, the study found that Egyptian AMV isolates are genetically stable with low nucleotide diversity. Genetic analysis of the AMV population suggested that the AMV populations differ geographically, and AMV CP gene is under mild purifying selection. Furthermore, the study proposed that the Egyptian AMV population had common evolutionary ancestors with the Asian AMV population. Antioxidant enzymes activity was assessed on N. glutinosa plants in response to infection with each AMV isolate studied, and the results revealed that the enzyme activity varied.
... AMV has caused outbreaks around the Alfalfa mosaic virus (AMV), a positive ssRNA virus that belongs to the Bromoviridae family, is a worldwide distributed phytopathogen [19,20] and was chosen as a target for RT-RPA-LFTs with both labeling approaches. AMV has caused outbreaks around the world and infected more than 150 plant species, damaging the harvest of different varieties, such as soybean [21,22], lucerne [23,24], potato [25,26], chayote [27], etc. The virus contains three genomic RNAs that encode four proteins. ...
The combination of recombinase polymerase amplification (RPA) and lateral flow test (LFT) is a strong diagnostic tool for rapid pathogen detection in resource-limited conditions. Here, we compared two methods generating labeled RPA amplicons following their detection by LFT: (1) the basic one with primers modified with different tags at the terminals and (2) the nuclease-dependent one with the primers and labeled oligonucleotide probe for nuclease digestion that was recommended for the high specificity of the assay. Using both methods, we developed an RPA-LFT assay for the detection of worldwide distributed phytopathogen—alfalfa mosaic virus (AMV). A forward primer modified with fluorescein and a reverse primer with biotin and fluorescein-labeled oligonucleotide probe were designed and verified by RPA. Both labeling approaches and their related assays were characterized using the in vitro-transcribed mRNA of AMV and reverse transcription reaction. The results demonstrated that the RPA-LFT assay based on primers-labeling detected 10³ copies of RNA in reaction during 30 min and had a half-maximal binding concentration 22 times lower than probe-dependent RPA-LFT. The developed RPA-LFT was successfully applied for the detection of AMV-infected plants. The results can be the main reason for choosing simple labeling with primers for RPA-LFT for the detection of other pathogens.
Potato virus M (PVM) is one of the most prevalent viruses infecting potatoes worldwide, showing a wide range of diversity in their populations; however, the diversity and genome information of PVM occurring in India is hardly known. The present study serologically detected the PVM in 22.8% of leaf samples collected from the potato fields, generated 13 coat protein (CP) genes and one complete genome sequence for the isolates from India, and identified four differential hosts confirming PVM-Del-144 as a distinct strain of PVM occurring in India. The phylogenetic analyses conducted based on the CP gene sequences (14 from India and 176 from other countries) suggested the existence of three evolutionary divergent lineages (PVM-o, PVM-d, and a new divergent group) in the PVM population, where isolates from India belong to only two clusters (PVM-o and PVM-d) within four sub-clusters. High levels of nucleotide diversity (0.124) and genetic distance (0.142) recorded among the isolates from India may be due to the deviation from the neutral evolution and experiencing population expansion in the past. The complete genome of the isolate Del-144 (KJ194171; 8,526 nucleotides) shared 92.2–93.9% nt sequence identity with the population of PVM-o, whereas it shared only 70.2–72.1% identity with PVM-d. In the phylogenetic analyses, Del-144 clustered with the isolates of PVM-o; however, it formed a separate branch away from all other isolates, indicating the diversity of the strain. Overall, this study revealed the diversity of the isolates of PVM from India and reported the first complete genome sequence of a distinct strain of PVM occurring in India.
