Molecular and serological studies on a plant virus affecting strawberry

ABSTRACT

Viruses form a major threat to the strawberry industry in Egypt causing severe economic losses. Rapid and simple methods for the detection of the major strawberry viruses are absent due to the lack of sensitive diagnostic tools. Plants showing virus-like symptoms [VLS] were collected from the field and subjected to indirect enzyme-linked immunosorbent assay [I-ELISA] tests using the polypeptide CP3 antiserum specific for whitefly transmitting geminivirus [WTG] in addition to Tomato yellow leaf curl geminivirus [TYLCV] polyclonal antiserum. In addition, plants were subjected to PCR as a molecular diagnosis test for further confirmation. Experiments proved that the virus could be transmitted mechanically, by viruliferous whiteflies and by grafting. Inoculated strawberry plants with viruliferous whiteflies showed curling and upward cup shape of the leaves. Primers specific for whitefly transmitted geminivirus were used in PCR diagnosis of the inoculated plants. Based on the positive molecular and serological diagnosis results, we concluded that the virus belongs to WTGs. PCR was also carried out for the inoculated plants using primers specific for TYLCV, however negative amplification was obtained indicating that the virus under this study is not a TYLCV. Electron microscopy of purified virus preparation showed the presence of geminate virus particles about 18x20 nm. Antiserum was raised against the purified virus and used for indirect-ELISA to measure the antigenicity of the raised antibodies. Western blot analysis was also used for confirmation of the specificity of the raised antiserum. The isolated virus was given the name strawberry leaf curl geminivirus [StLCV] and it represents the first record of WTG that infect strawberry plants in Egypt