الفهرس | Only 14 pages are availabe for public view |
Abstract This study was conducted at Plant Pathology Laboratory and Greenhouse of Botany department- Faculty of Agriculture-Menoufia University and Virology Lab- Plant Pathology institute-Agricultural Research Center-Giza. During 2013/2014 and 2015/2016 growing seasons, different legum fields at Menoufia Governorate were surveyed for virus infections. In order to try to reach a security means to resist viral diseases in legumes without resorting to the use of pesticides or harmful chemicals within the framework of preserving the environment and public health and the gradual shift towards development of clean agriculture. Through, the assessment of diseases incidence and severity of viruses on bean and faba bean crops. 1. Serological tests (direct and indirect ELISA test, Tissue blot immunoassay (TBIA) and Dot blot immunoassay (DBIA) ,were used to check the collected samples against three viruses BCMV , BYMV, BBMV. All samples were infected with BYMV. 2. The host range of BYMV was studied and indicated that the virus has short host range, mostly belonging to the leguminous family and some species belonging to the Chenopodiaceae family and did not prove the occurrence of some of Solanaceae family. 3. The results indicated that electrophoresis analysis of RT-PCR product show a single fragment of ~ 900 bp. The nucleotide of Egyptian isolate were compared with eight isolates available in the Gen Bank. The percentage of similarities was 98% to the Syrian isolate, while it was ranged from 94-98 % in the other isolates. 4. Study the effects of seven inducers (Sex botanical extracts and Salicylic acid )in induction systemic resistance (SAR) in bean plants against BYMV under greenhouse and open field. This part studied the effect of plant extracts (Dianthus caryophyllus, Glycyrrhiza glabra, Psidium guajava, Solanium nigrum, Spinacea oleracea and Thymus vulgaris ) and salicylic acid on the induction process. The bean plants were sprayed with three concentrations ( extracts 5, 10, 15 %) and salicylic acid ( 25 , 50, 100 mM). and then BYMV infection on these plants. 5. Virus infectivity was determined as indicator of control. Reduction in the disease severity percentage was recorded as result to spraying bean plants with different treatments, compared with control. Also, concentration of the virus was biologically assayed as means of local lesions on indicator plant. Highest inhibition of virus infectivity due to Dianthus caryophyllus extract (95.8 %), Salicylic acid (91.5%) Solanum nigrum( 90.5%), Spinacea oleracea (81%), Thymus vulgaris (68.4%), Glycyrrhiza glabra (65.8 %) and Psidium guajava (42.1%) extracts, respectively compared with control. 6. Effect of treatments on symptoms and growth of bean plants, it has been observed that most of treatments led to the emergence of symptoms on leaves compared to infected plants. 7. Photosynthetic pigments content (as Chlorophyll a, b plus carotenoids) were reduced, generally in infected plants than healthy ones. But, when bean treated with the tested elicitors pre-inoculation, Chl a , Chl b and carotenoids were increased as result to spraying with different inducers. The same trend was observed when inoculated plants were treated with the same order of elicitors 8. Peroxidase and Polyphenol oxidase were determined in sprayed bean plants in three periods of 6 , 13 and 21 days after spraying, using Spectrophotometer, results were as follows: It found that both enzymes decreased compared to infected plants to close at its highest level at 21 days of treatment and infected, while recorded low activity in healthy plants. 9. Antiviral proteins as one of the protein contents and product of induction process were markedly increased in treated bean plants than non-treated ones. Electrophoretic for proteins using SDS-PAGE showed new protein bands with molecular weight previously known for antiviral proteins were elicited by different inducers. The clearest resulting from spray Dianthus caryophyllus extract, where anew protein band appeared at molecular weight (69 kD) is not present in healthy and infected plants, as well as the other treatments. 10. Histopathological changes as response to SAR induction was examined in the inoculated bean leaves and sprayed with inducers using light microscopy. Tissue alterations were observed as progressive increase in lignin accumulation in epidermal cells, number of xylem arma and phloem layers. Mesophyll cell of infected cell, showing folding and layering of cell wall and remains of host palisade cell walls. 11. Study of cytological changes revealed large differences between healthy, infected and induced cells by electron microscope. Generally, noticed that treated plants were better in their growth than non-treated plants as result to regularity in their cell walls and increase in the number of chloroplasts and regularity in shape and size of chloroplasts compared to cell plant infected with the virus. 12. The trail was carried under field conditions during winter season of 2015, at the farm of Faculty of Agriculture, Menoufia University. The experimental plot size was 6 long and 2 wide, this plot contained 9 ridges of 60 cm width. Each replicate (one ridge with 10 plants), data revealed that: The virus was found to produce changes in some physiological and biochemical components of bean leaves. Including reduction in chlorophyll pigments, peroxidase and polyphenol oxidase. Data concerning the antiviral activity of plant extracts and SA acid against BYMV, and showed that, all treatments increased the content of photosynthetic pigments, compared with infected control. And decreased the activity of enzymes compared with infected plants. 13. Study of some vegetative characters and the yield, under the field conditions, found that viral infection lead to a decrease in production as well as a decrease in leaf area of plants compared to healthy plants. But, when bean treated with the tested elicitors pre-inoculation, leaf area and the yield (The dry weight of total pods and the dry weight of total seeds and) were increased as result to spraying with all inducers, compared to non-treated infected plants. |