Bunchy top banana is a destructive viral disease in many countries including Egypt. It causes severe losses because infected plants produce no fruit. This study was designed to detect viruses affecting banana plants (bunchy top banana virus BBTV and CMV). Results revealed that the early symptoms of BBTV-infected banana were dark green streaks on midrib of the lower portions of leaves. The newly growing leaves were brittle. They gather at the top of plant making a rosetting shape. CMV-infected banana were characterized by a conspicuous interveinal chlorosis of the leaves. BBTV and / or CMV mixed infection were detected with 2 percent triphenyl tetrazolium chloride in discs of suckers infected. The viruses were detected via the precipitation serological reaction using specific IgG by DAS-ELISA and DIBA. BBTV was isolated by using syringe on healthy banana plants and BMV was isolated by local lesions assay on Chenopodium amaranticolor. BBTV has limited host rang, it reacts with mosaic on Canna sp. while CMV exhibited different systemic symptoms on Cucumis sativus, Sorghum vulgaris, Zea mays, Musa sp., Nicotiana tabacum, Datura metel, Lycopersicon esculentum, local symptoms on Ch. amaranticolor, Ch. quinoa, Vigna sinensis, V. unguiculata and local lesions followed by systemic infection on Cucurbita pepo and N. glutinosa. BBTV and CMV are transmitted by infective Pentaloria nigronervosa in semi- and non-persistent manner respectively. PCR as an enzymatic procedure was used successfully to detect BBTV and CMV of naturally infected banana plants. The PCR amplification of BBTV-DNA and CMV-RNA was carried out on the total DNA and RNA isolated from naturally infected plants using specific coat protein (PC gene). The results showed that BBTV and CMV respectively. Examination of ultrathin sections prepared from naturally infected banana leaves revealed disorganization and destruction of chloroplasts, degeneration of mitochondria and vacoulation in the cytoplasmic and membrane and abnormal osmophilic body in cytoplasm. (Author's abstract). |
