齒舌蘭輪斑病毒（Odontoglossum ringspot virus）在四季蘭植株上之分佈差異與病毒檢測應用

Distribution of Odontoglossum ringspot virus on plant of Cymbidium spp. and Its Application on Virus Detection

四季蘭乃屬於蕙蘭屬（Cymbidium spp.）蘭花，一般所稱的小花蕙蘭，包括報歲蘭、四季蘭、素心蘭、春蘭以及寒蘭等。近年來國內大規模的經濟栽培，以及出口外銷所得之經濟效益，使得小花蕙蘭躍居為相當重要的經濟花卉。病毒病的發生影響蘭花的生產品質與經濟價值，傳統上蕙蘭以無性分株法為主要繁殖方法，因此，母株若感染病毒，其後代所有子芽都會受到感染而逐漸衰弱。

"Cymbidium spp. are popular ornamental crops with economical importance in Taiwan. Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) are two major viruses infecting orchids worldwide. Cymbidium plants are mostly propagated by transplanting the lateral shoots. Therefore, the virus-indexing work of mother plants before planting is very important to make sure virus-free of shoots for virus control in Cymbidium spp. The concentrations of ORSV accumulated in tissues of different leaf orders, roots, and leaf sheaths of Cymbidium spp. cultivar Yu-Wha plants were compared in this study. Ten pots of ORSV-infected Cymbidium plants were selected for the virus detection. Our results showed that ORSV is unevenly distributed in whole plant. The detection rates of ORSV existing in the different portions of plants were vary that 97.4% for the old leaf sheaths, 85.3% for roots, 71% for the upper portion of leaves and 75.9% for the middle portion of leaves, respectively. Local lesions were developed at 4 days after mechanically introduced those virus-positive samples including the old leaf sheaths, roots and leaves to leaves of Chenopodium quinoa. Further serological analyses of western blotting and SD-Simmunodiffusion indicated that all of the local lesions were induced by ORSV infection. The biological and serological characterizations of ORSV in the old leaf sheaths revealed that ORSV is survival in this site and with high risk to be a virus inoculum source. Our results also revealed that the leaf sheath would be a better sampling site for increasing the virus detection rate to improve the efficiency of virus indexing on plants of Cymbidium spp."