臺灣蘭花毒素病害之研究

Studies on the Virus Diseases of Cymbidium in Taiwan

東亞蘭患病毒的病徵為呈現淡黃色條斑或嵌紋，有時間雜褐色塊斑，80%以上之罹病株經證明是受CyMV之感染。亦有發現被CyMV及ORSV共同感染之植株。CyMV在葉汁內之不活化溫度為65～70℃，稀釋終點為介於1O-5～1O-6之間，在25°C室內可耐保存15天之久，在電子顯微鏡下（病毒顆粒）為絲狀略彎曲，大小為480 X 15nm。ORSV在葉汁內之不活化溫度為70～75°C，稀釋終點為介於1O-6～1O-7，在25°C室內可耐保存15天之久，病毒顆粒在電子顯徵鏡下觀之，為桿狀，大小寫3 1O X 22nm。罹病植物葉片，利用高低速變換離心及PEG沉澱步驟可以獲得部分純化之病毒。利用罹病葉浸漬，陰染，電子顯微鏡之觀察，可迅速達到植物病毒檢疫之目的。

The virus diseased Cymbidium showed pale yellow streaks or mosaic, sometimes mixed with sunken brown spots. Eighty percent of diseased plants were proved to beinfected with CyMV. The plant both infected with CyMV and ORSV was also found in orchid garden. The thermal inactivation point of CyMV and ORSV were between 65~70°C and 70~75°C and the dilution end point were between 10-5~10-6 and 10-6~10-7, respectively. Aging in vitro of both viruses were 15 days at 25°C. Under electron microscopy, the virions of CyMV were sinuous rods with the size of 480 X 15 nm and the virions of ORSV were rod-shapped with the size of 31O x 22 nm. Partially purified viruses were obtained by using polyethylene glycol precipitation and differential centrifugation. Electron microscope is an excellent instrument for the rapid diagnosis of plant viruses from dipped and negative stained materials.