The activity of Rhizobium japonicum against the soil-borne pathogens Fusarium solani and Macrophomina phaseolina as causative agents of soybean root rot disease in both culture medium and soil was evaluated. Rhizobial culture filtrate caused an inhibition of the fungal radial growth of Fusarium solani and Macrophomina phaseolina on potato dextrose agar medium amended with the filtrate compared with control. The addition of rhizobial culture suspension to the soil contaminated by the two pathogens, Fusarium solani and Macrophomina phaseolina and their interaction, in pots, improved seed germination percentages and reduced the root rot disease index significantly. The sowing of rhizobial coated seeds in soil contaminated by Fusarium solani and Macrophomina phaseolina separately and in combination, in the field, increased seed germination significantly and induced a high reduction in disease severity for the same previous combination under field conditions. These results indicate that rhizobia could be an important element in root rot disease management.
his study was carried out to evaluate the efficiency of electrophoresis on SDS- poly acrylamide slap gel and immunostrip techniques for detection of Tobacco mosaic virus (TMV, genus Tobamovirus) and Cucumber mosaic virus (CMV, genus Cucumovirus, family Bromoviridae), compared with symptoms on diagnostic plants for the two viruses. The results obtained showed that the two methods were effective. The analysis of samples of purified CMV, total proteins from infected cucumber plants, and extracts from infected plants with or without chlorophyll, by electrophoresis on 10% polyacrylamide slap gel containing 0.1% SDS showed two bands of 24 and 26 kd in size, and absent in samples of total protein or extracts of healthy plants. These two proteins represent the coat protein (CP) of CMV. In addition, one 18 kd protein band appeared on SDS- polyacrylamide gel profile which represent the CP of TMV, when samples of purified virus, total protein of infected plants, and plant extracts with or without chlorophyll were analyzed. This band was absent in similar samples from healthy plants. The test of immunostrip specific for CMV showed positive reaction with extracts from melon, cucumber, winter squash, and zucchini infected plants. Similarly, a positive reaction with immunostrip specific for TMV appeared with extracts from tobacco, tomato infected with TMV. No reaction was obtained with healthy plants extract. These results were similar to those obtained from indicator plants for the two viruses.
This study was conducted to evaluate the efficacy of different techniques for extraction and purification of Tomato yellow leaf curl virus (TYLCV). An isolate of the virus free of possible contamination with other viruses infecting the same host and transmitted by the same vector Bemisia tabaci Genn. was obtained. This was realized by indicator plants and incubation period in the vector. Results obtained revealed that the virus infect Nicotiana glutinosa without visible symptoms, while Nicotiana tabaccum var. White Burley was not susceptible to the virus. The incubation period of the virus in the vector was found to be 21 hrs. These results indicate that the virus is TYLCV. Results showed that Butanol was more effective in clarification the sap and eliminate of plant proteins and chlorophyll. The use of citrate buffer at pH 8 amended with reducing agents and EDTA to prevent the oxidation of phenolic compound was found to be suitable in maintaining the biological activity of the virus during extraction. The quantity of the virus obtained was 3.05 mg/100 gm leaves with absorption ratio of 1.4 at 260/280 nm which represent standard value for TYLCV.
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