Document Type : Original Article
Authors
1
Virus and Phytoplasma Research Department, Plant Pathology Research Institute, Agricultural Research Center, Giza, Egypt
2
3Department of Economic Entomology and Pesticides, Faculty of Agriculture, Cairo University, Giza, Egypt
3
Biochemistry Department, Faculty of Agriculture, Cairo University, Giza, Egypt.
Abstract
In 2013, a witches’ broom phytoplasma was detected in Hibiscus (rosa-sinensis) shrubs using nested polymerase chain reaction (nested-PCR) in five Egyptian governorates, Alexandria, Fayoum, Giza, Mansoura, and Qalyubia. In the present study, phytoplasma of the same kind was detected in other samples from the same shrubs and locations. The predicted PCR product size was ~1200 bp. Quantitative measurements of plant metabolism can provide a broad view of the biochemical status of the plant. Carotenoid and chlorophyll content was decreased while starch content and soluble sugar increased, indicating the decline in photosynthetic efficiency and metabolic disorders in the leaves. Levels of antioxidant enzymes and non-enzymatic antioxidants were increased more than 100% and 200% in the diseased leaves respectively, compared to healthy plants. These results seem to confirm that more enzymatic and non-enzymatic antioxidants occurring together might positively affect defense activities and cell wall enhancement to deal with the over-production of reactive oxygen species and pathogen stress. Increasing these antioxidative defense systems, in turn, may affect the stability of hibiscus shrubs, as shrubs may pass the infection to other crops over the years through phloem-sucking insects such as leafhoppers. Five different concentrations of hydrophilic nano-silica (NS), from 100 ppm to 500 ppm, were tested under laboratory conditions on mortality and survival rates of phytoplasma vector, green leafhopper, Empoasca decipiens Paoli. Two different applications were used to determine the effectiveness of NS-concentrations. Among these concentrations, 500 ppm had the highest effect on mortality (0% survival) for both nymphs and adults of E. decipiens.
Keywords
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