Abstract
Abstract
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.
Funder
Agricultural Research Center
Publisher
Springer Science and Business Media LLC
Subject
Microbiology (medical),Microbiology
Reference69 articles.
1. Mellema JR, van den Berg HJN. The quaternary structure of alfalfa mosaic virus. J Supramol Struct. 1974. https://doi.org/10.1002/jss.400020104.
2. Kumar A, Reddy VS, Yusibov V, Chipman P R, Hata Y, Fita I, Fukuyama K, Rossmann MG, Loesch-Fries LS, Baker TS, Johnson JE. The structure of alfalfa mosaic virus capsid protein assembled as T=1 icosahedral particle at 4.0-Å resolution. J Virol. 1997; https://doi.org/10.1128/jvi.71.10.7911-7916.1997.
3. Thole V, Miglino R, Bol JF. Amino acids of alfalfa mosaic virus coat protein that direct formation of unusually long virus particles. J Gen Virol. 1998; https://doi.org/10.1099/0022-1317-79-12-3139.
4. Balasubramaniam M, Kim BS, Hutchens-Williams HM, Loesch-Fries LS. The photosystem II oxygen-evolving complex protein PsbP interacts with the coat protein of alfalfa mosaic virus and inhibits virus replication. Mol Plant Microbe Interact. 2014. https://doi.org/10.1094/MPMI-02-14-0035-R.
5. Edwardson JR, Christie RG. Alfamovirus genus. Alfalfa mosaic virus species. In: Edwardson JR, Christie RG, editors. Viruses infecting peppers and other solanaceous crops. Vol. 1. Gainesville: University of Florida Press; 1997. p. 63–94.