Radwa M. Shafie’s research while affiliated with Plant Pathology Research Institute and other places

Alfalfa mosaic virus (AMV) was isolated from naturally infected periwinkle plants obtained from Giza Governorate. Characteristic symptoms, including yellow blotches, vein banding, and chlorosis, were observed. Through the isolation of single local lesions, the virus was purified biologically using Chenopodium amaranticolor Coste & Reyn. Identification of the virus was conducted by employing various methods, including symptomatology, transmissibility, and serological assays such as DAS ELISA, electron microscopy, and molecular detection. lactoferrin (LF) at different concentrations (1000, 750, 500, 250, and 100 mg/L) was used as a resistance inducer to mitigate alfalfa mosaic virus infection. The highest concentration of lactoferrin (LF), applied five days prior to inoculation, resulted in a 90% reduction in viral infection. All lactoferrin concentrations led to significant increases in phenol levels and enzyme activity. Treatment with different concentrations of LF resulted in the induction of new proteins.The maximum levels of vinblastine and vincristine were detected at the highest lactoferrin concentration, reaching 0.393 and 0.399 respectively, five days post inoculation. Lactoferrin treatments also increased the concentrations of photosynthetic pigments, including chlorophyll a, chlorophyll b, and carotenoids.

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.

Plant viruses are a global concern for sustainable crop production. Among the currently available antiviral approaches, nanotechnology has been overwhelmingly playing an effective role in circumventing plant viruses. Alfalfa mosaic virus (AMV) was isolated and identified from symptomatic pepper plants in Egypt using symptomatology, serological tests using the direct ELISA technique, differential hosts and electron microscopy. The virus was biologically purified from a single local lesion that developed on Chenopodium amaranticolor. The AMV infection was further confirmed using an AMV coat protein-specific primer RT-PCR. We further evaluated the antiviral potential of chitosan nanoparticles (CS-NPs) and chitosan silver nanocomposites (CS-Ag NC) in different concentrations against AMV infections in pepper plants. All tested concentrations of CS-NPs and CS-Ag NC induced the inhibition of AMV systemically infected pepper plants when applied 24 h after virus inoculation. The foliar application of 400 ppm CS-NPs or 200 ppm CS-Ag NC produced the highest AMV inhibitory effect (90 and 91%) when applied 24 h after virus inoculation. Treatment with CS-NPs and CS-Ag NC considerably increased the phenol, proline and capsaicin contents compared to the infected plants. Moreover, the agronomic metrics (plant height, fresh and dry pod weights and number of pods per plant) were also significantly improved. According to our results, the potential applications of CS-NPs and CS-Ag NC may provide an effective therapeutic measure for better AMV and other related plant virus management.

Aims: Strawberry (Fragaria ananassa Duch.) is a member of the family Rosaceae and one of the most important vegetable crops in Egypt for local fresh consumption and exportation. Suspected symptoms of Strawberry mild yellow edge virus (SMYEV) on naturally infected strawberry plants were observed in Al Qaluobia Governorate. The main goal of this study was to develop a novel eco-friendly biogenic silver nanoparticle using clove (Syzygium aromaticum) (Sz-AgNPs) aqueous extract to control viral infection. Methodology and results: Mechanically inoculated sixteen plant species representing seven families, Apocynaceae, Chenopodiaceae, Cucurbitaceae, Fabaceae, Moraceae, Rosaceae and Solanaceae, were used as hosts for SMYEV. Systemic mosaic, chlorotic local lesions, vein clearing, marginal chlorosis, marginal necrosis, yellowing and vein banding were observed 7 to 20 days post-inoculation. Transmission electron microscopy (TEM) of diseased tissues revealed severe degeneration of the chloroplasts and nucleus structures and the formation of cell wall protrusions. Sz-AgNPs were characterized using UV-Vis spectroscopy, TEM, dynamic light scattering (DLS) and Fourier transform infrared (FTIR). Foliar application of Sz-AgNPs (200 µg/mL) 24 h post and/or concurrently with SMYEV inoculation dropped the infection rate by 90% and 55%, respectively, whereas it was only reduced by 35% when applied 24 h prior to viral inoculation compared to control groups. DAS-ELISA and RT-PCR verified SMYEV inhibition (75-90%) in all plants treated with 200, 150 and 100 µg/mL Sz-AgNPs 24 h post-viral inoculation. Complete viral eradication was attained by applying Sz-AgNPs at a concentration of 200 μg/mL 24 h post-virus inoculation. Moreover, the total phenols, indoles, Vitamin C, total flavonoids and citric acid contents were not significantly affected by Sz-AgNPs treatment compared to healthy control groups. Conclusion, significance and impact of study: In conclusion, Sz-AgNPs suppressed SMYEV by 75-90% when applied 24 h post-virus inoculation. Eco-friendly Sz-AgNPs could be used for controlling viral infections and avoiding the rejection of exportable strawberries due to the use of harmful pesticides.