Potato virus Y (PVY) causes serious loss in the yield and quality of potatoes. The effect of chitosan nanoparticles (CS-NPs) on the regeneration response and production of PVY-free plants under in vitro conditions was studied. Murashige and Skoog (MS) medium supplemented with 0.1 mg L⁻¹ Gibberellic acid (GA₃), 0.1 mg L⁻¹ Naphthalene acetic acid (NAA) and 500 mg L⁻¹ malt extract was used for regeneration of plantlets from sprouts. Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay (DAS-ELISA) and Reverse Transcript Polymerase Chain Reaction (RT-PCR) was used for virus indexing of the mother plant and in vitro-regenerated plantlets. Explants of PVY positive potato plants were cultured on same medium amended with 100, 200, 250, and 300 mg L⁻¹ of (CS-NPs). Shoot regeneration decreased from 100 to 200 mg L⁻¹ as the concentrations of antiviral (CS-NPs) up to 250 mg L⁻¹. It was decreased with the increase in the concentration of the antiviral (CS-NPs) up to 300 mg L⁻¹. Antiviral (CS-NPs) at the concentration of 250 mg L⁻¹ showed a positive effect on shoot regeneration. In vitro-regenerated plantlets were virus free and tested negative in both ELISA and RT-PCR. The level of 100 mg L⁻¹ of (CS_NPs) produced 38.8% PVY-free plants and 30.50% of cultures showed shoot regeneration. The level of 200 mg L⁻¹ of (CS-NPs) produced 49.6% PVY-free plants while 46.8% of cultures showed shoot regeneration. The level of 250 mg L⁻¹ of (CS-NPs) was the most effective and produced 100.0% PVY-free plants and 100.0% of cultures showed shoot regeneration. Histopathological changes simultaneously with elucidation of resistance and growth enhancement were evident in the treated plants with (CS-NPs) than those untreated control. In conclusion, (CS-NPs) treatment is an effective tool to produce PVY-free sprouts explants and has potential for producing virus-free planting material for the potato industry.

In 2020, the leaves and fruit of 50 pumpkin plants with suspected cucumber mosaic virus (CMV) symptoms of leaf mosaic, vein yellowing, and mild leaf curling were collected from Sharq El-Owainat (Al Wadi El-Gaded governorate), a new reclamation land in Egypt. This study was aimed at deciphering and characterizing the causal agent of the leaf yellowing disease associated with pumpkin plants in Egypt. The causal agent was identified by serological, cytological, and molecular means. The serological identification by DAS–ELISA confirmed the presence of CMV in 20% of the plants. The cytological identification by electron microscopy revealed typical cucumovirus isometric particles of 28–30 nm diameter in the cytoplasm of the leaf parenchyma, epidermal cells, the integument, and the nucleus. Molecular characterization by one-step reverse transcriptase-PCR yielded the required size of amplicon (678 bp) for CMV. Additionally, mechanical sap inoculation was used to determine the host range and symptomatology of the isolated CMV in seventeen different plant species belonging to six different plant families. CMV replicated, moved systemically, and induced a range of symptoms in sixteen plant species. The isolated CMV was transmitted to pumpkin plants at a 16.4% rate by seeds. CMV-infected pumpkin plant leaves were characterized by a substantially low concentration of photosynthetic pigments, a high level of reducing sugars, relatively low protein levels, and a significant increase in total phenol contents, implying their potential role as antiviral agents. Ultrathin sections of infected cells revealed histological changes and cytological abnormalities in comparison to healthy plants. This is the first identification of CMV on new reclamation land in Egypt, pinpointing its swift spread, which could pose a major constraint to pumpkin production in Egypt.

Citrus Excortis Viroid (CEVd) is California's first viroid disease described on citrus trees in 1948. It is the largest viroid of citrus with 371 nucleotides. The disease causes distinguished symptoms of bark scaling on rootstocks of citrus trees grafted onto trifoliate rootstocks causing severe stunting of trees grafted on these rootstocks. The use of indicator host plants for CEVd detection had been successful using clean matured fresh cuttings of specific indicators (Etrog lemon, Volkameriana lemon), which were grafted with the infected plants and cultured in plastic bags after a short dipping in IBA solution for 10 sec. Ideal clear symptoms were observed 18 days after grafted inoculation on new growing leaves of unique indicators. The obtained results of the biological indexing trail were confirmed using RT-PCR and transmission assays using some hosts such as Solanum melongena, Piper nigrum, Gynura auranisa and Solanum esculentum (Castel rock) with infectious sap. Results showed that cold treatment at 4 °C for 6 months companies with chemotherapy with 10, 20 and 30 mg/L Virazol and thiouracil gave plants free-viroid. viroid infection was reduced by using the highest concentrations of Virazol and thiouracil at 30 mg/L reaching 80 and 55%, respectively. The recovered plants were examined by RT-PCR. Cold therapy treatment and chemotherapy are effective and attractive techniques for eradicating CEVd from citrus trees in Egypt. Virazol has the greatest effect on the elimination of viroid because the viroid-free percentages by Virazol were higher than those obtained using thiouracil.

One of the most significant banana diseases in Egypt is Banana Bunchy Top Disease, which is brought on by the Banana Bunchy Top Virus (BBTV). The creation of BBTV-free plantain seedlings from infected banana plants was the main goal of this investigation. Four governorates provided samples (Qalubia, Giza, Ismailia, and Behira). All collected samples underwent BBTV testing using DAS-ELISA.The results revealed that The virus infection was recorded in all inspected governorates with different ratios 1/15, 3/15, 5/15, and 2/15 of the samples were infected, respectively. The diagnostic host of BBTV was limited, ginger, and bird of paradise using mechanical inoculation, while only banana and ginger were infected using insect inoculation with P. nigronervosa. Polymerase chain reaction, (PCR) based detection of amplicon from BBTV infected banana tissues 476 bp. The multiple sequence alignment showed that EGY-Bahair isolates had a high similarity of 99.7% with isolate BBTV-replicate from India. The phylogenetic tree for the BBTV- Eg Bahira isolates is based on the partial nucleotide sequence alignment of the DNA-A genome. BBTV was successfully eradicated from infected plants utilizing a combination of meristem tip culture and thermotherapy at 40o C for two months. Virocide provided the greatest polyphenol oxidase activity (1.64 and 1.78) as well as highly enzymatic activity (2.021 and 1.96 for peroxidase). Significant biochemical changes represented in a relative reduction in Chl a, Chl. b and carotenoid contents. It was observed that the highest reduction in Chlorophyll b, 51.47% followed by chlorophyll a+b 51.27, chlorophyll a, 51.17, and Carotenoids -2.65 respectively

Sesamum phyllody is a severe disease that displays various symptoms such as floral virescence, phyllody, proliferation, yellowing, cracking of seed capsules, and the formation of dark exudates on foliage. Infected plants were found to have blue areas in the phloem region using Diane’s stain, and phytoplasma structures in the phloem sieve elements were detected using transmission electron microscopy. The amplification of a phytoplasma-specific 1200-bp 16S recombinant DNA (rDNA) fragment confirmed that the plants were infected with a phytoplasma. To regenerate phyllody-free plantlets from meristem tips, Murashige and Skoog medium was utilized and phytoplasma indexing was performed using nested PCR (nPCR) on the mother plant and the in vitro-regenerated plantlets. In an effort to produce phyllody-free plants, explants from phyllody-positive Sesamum plants were cultured in Murashige and Skoog medium with varying concentrations of silver nanoparticles (Ag NPs). As the concentration of Ag NPs increased up to 300 mg L-1, shoot regeneration was reduced. However, in vitro-regenerated plantlets at a concentration of 250 mg L-1 were tested negative for phyllody and proved to be phyllody free. The most effective concentration was found to be 250 mg L-1, resulting in 100% phyllody-free plants and 100% of cultures showing shoot regeneration. Thus, treatment with Ag NPs is a promising technique for producing phyllody-free Sesamum plants.