Studies on spinach yellow mosaic disease. I. Isolation and identification of cucumber mosaic virus

平地菠菜的栽培，普遍發生黃化嵌紋病，將罹病植株經不同離心力分離，所得沉澱再分別用 Sepharose CL-4B 分子篩孔色層進一步純化，經汁液接種及電子顯微鏡觀察，發現在100,000 g 分離純 化試料之第一吸收峰處出現對菠菜有病原性，並觀察到大小約29 nm 的多量球形粒子存在。在汁液 接種測試中，對原寄主菠菜苗所出現的病徵與原來的症狀較相同，而認為是本病的主要病原。由單一 分離系(PL) 所得之病原，其物理性質為耐溫度性在50 - 55℃，耐稀釋性為1 0- 2 - 10- 3 倍，耐保存性在 4℃ 下時則為6 - 8天、室溫下為3 - 5 天。病毒鞘蛋白經S D S - PAGE 電泳其次單位蛋白分子量為2 5 K d。經家兔免疫注射製作血清其力價為1024 倍，以Ouchterlony 法分析血清類緣關係，甜椒C M V 與田間菠菜罹病汁液與純化病毒呈完成同質反應(homologus) 之現象。綜合試驗結果得知造成田間菠 菜黃化嵌紋病毒主要的病毒為胡瓜嵌紋病毒(Cucumber mosaic virus) 的一種。 Spinach grown in lowland areas of Taiwan was found widely exhibiting yellow mosaic symptoms, which is possibly caused by virus infection. A virus isolate (PL) was obtained from the symptomatic spinach and subsequently tested for its infectivity on 27 plant species from 9 Families by mechanical inoculation. Twelve species in Chenopodiaceae and Solanaceae but none of the plants from Leguminosae and Cucurbitaceae were infected. Inoculation of the PL isolate on spinach seedling induced symptoms similar to those observed from the fields. Infectious virus particles of PL were obtained by centrifuging the homogenates of the diseased tissue at 100,000 g for 60 min followed by chromatographing through Sepharose CL-4B column. In electron microscopy, the morphology of virus particles was found to be isometric about 29 nm in diameter. Similar sized and shaped virus particles were also detected in ultra-thin sectioned diseased spinach tissue. The thermal inactivation point of PL isolate is 50-55℃, dilution end point is 10- 2 to 10- 3 and the longevity in vitro is 3 to 5 days under room temp and 6 to 8 days at 4℃. By electrophoresis analyses, molecular weight of the coat protein subunit of PL was estimated as 25 kDa. An antiserum was prepared against the purified virions and found to react strongly with its homologous antigen but not to the healthy control spinach in SDS-immunodiffusion test. Furthermore, this antiserum gave indistinguishable reaction against antigens of PL isolate and an isolate of cucumber mosaic virus (CMV) from sweet pepper, indicating that PL isolate from spinach was serologically identical to CMV. This result corresponds to those documented in USA and Japan that CMV is a causal agent of spinach mosaic disease