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Single pure isolates of banana bunchy top virus (BBTV) strains were obtained through transmission by vector aphid( Pentalonia nigronervosa ). The BBTV was differentiated into such four strains as severe (S), intermediate (I), mild (M) and latent (L) strains according to symptom expression on Cavendish banana in Taiwan.S strain induced severe typical symptoms including stunted, chlorotic margin and narrow, erect new leaves, bunchy top, vein clearing and dark green dot-dash streaks on petioles. I strain caused mild stunt, slight leaf atrophy and distinct vein clearing. M strain-infected banana plants produced no distinct symptoms except dash-like vein clearing scarcely. No visible symptoms was developed in L-strain-infected plants which were looked like healthy plants. The four strains were differentiated into six genotypes by polymerase chain reaction ( PCR ) amplification with 3 primer pairs (C1-CR, S-CR, SR-CR) followed by electrophoresis analysis. The monoclonal antibodies ( McAbs ) developed against BBTV were recognizing the common epitopes of Taiwan strains, therefore the selected McAb ( 2H6 ) reacted with the all strains of BBTV in Taiwan. However, the 2H6 McAb did not react with a severe isolate of BBTV from Sarawak, Malaysia.The virus is transmitted by the banana aphid in the persistent manner. Although the adult aphids reared on infected banana plants were BBTV positive in PCR tests, none of the offspring of the viruliferous adults were BBTV positive. This fact indicated that BBTV was not transmitted through axeual reproduction. BBTV was transmitted by non-alate adult banana ahpids transmission rate more than alate aphids. The minimum acquisition feeding period of banana aphid is 2 hours. BBTV may multiply in a aphids vectors in way of propagative persistence. The PCR genotypes of BBTV strain in banana identified by PCR tests with the three primer pairs. In direct fluorescence detection in thloem with on UV microscope, the 4 strains showed different degrees of specific fluorescence ( SF ), S strain produced largest amount of SF, L strain produced least SF. At 40℃or 50℃BBTV in tissue dried preserved at 4℃maintained serological activity for at least one year. Appication of systemic insecticides showed insecticidal efficacy for prenention BBTV transmission by banana aphid. No symptom appeared on banana plantlets treated with soil application of comfidor 2GR( 7.5g/plant ) before inoculation by viruliferous aphids.
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