Identification and aphid transmission of an isometric virus isolated from Lutao copperleaf (Acalypha caturus Blume) showing mosaic symptom in Taiwan

• Main Authors: Wu Min Hung, 吳旻皇
• Other Authors: Chen Tsang Hai
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/96124029986373197424

碩士 === 國立屏東科技大學 === 植物醫學系所 === 99 === Lutao copperleaf (Acalypha caturus Blume) is an evergreen small shrub, which belongs to the family Euphorbiaceae, Acalypha genus. Lutao copperleaf is widely grown in Philippines and Sumatra. In Taiwan, it is distributed at Dulan, Lyudao, and Lanyu of Taitung regions. In early days, Lutao copperleaf was important forage for feeding formosan sika deers in Lyudao. Also, Yami tribe people get the leaves to feed sheep and deers in Lanyu. In 2009, an undescribed virus disease, yellow and green mosaic on the leaves of Lutao copperleaf was found in Taitung, Taiwan. The field survey revealed that the rate of incidence was about 35%. An isometric of KC-1 virus isolate of 21-24 nm in diameter was isolated from Lutao copperleaf showing mosaic on leaves through means of Aphis gossypii transmission. KC-1 virus isolate infected Lutao copperleaf induced mosaic and systemic vein yellow or mosaic symptom on leaves which are similar to the field diseased copperleaf. The KC-1 virus isolate cannot be transmitted by mechanical inoculation and seed transmission except the A. gossypii transmission. The results of testing KC-1 virus isolate of aphid vector transmission by Myzus persicae and A. gossypii showed that only A. gossypii could transmit. A. gossypii could continuously spread KC-1 virus isolate. Its minimal duration of acquisition and inoculation access periods by A. gossypii were 12 hours and 30 minutes, respectively; its transmission efficiency was 19% and 11%, respectively. Single aphid could effectively transmit KC-1 virus isolate with the transmission efficiency of 14%. The nymphs of aphids showed higher transmission efficiency than the adult aphids. The A. gossypii could retain KC-1 virus isolate for 13 days post virus acquisition. The virus could passage to progeny viviparae of A. gossypii, and can continue pass to the F3 generation. The results of the host range test indicated that the virus could only infect 2 families, 18 plant species belonging to Euphorbiaceae and Solanaceace among 62 plant species in 9 families tested. The ultrathin section of a vein of Lutao copperleaf infected with KC-1 virus isolate showed crystalline arrays of virus particles and cytoplasma granulated in phloem cell. The purified virus preparation was obtained with a yield of 0.33 mg/100 g from infected tobacco leaves. In conclusion, the virus particle morphology, aphid-borne transmission characteristics, and histopathology of the KC-1 virus isolate on the Lutao copperleaf showed that the presumption of KC-1 virus of this study was a phloem-limited virus, and might belong to Luteoviridae. This is the first report on Lutao copperleaf mosaic disease in the world.