木瓜毒素病純系病毒之分離與二種不同病徵型病毒之寄主範圍與物理性質之比較

Isolation and Comparison of Two Isolates of Papaya Ringspot Virus in Taiwan

張清安(Chin-An Chang)

《中華農業研究》 28卷3期 (1979/09) Pp. 207-216

https://doi.org/10.29951/JARC.197909.0010

摘要

本省之木瓜毒素病可於兩種藜科植物（Chenopodium amaranticolor及C. quinoa）上產生局部病斑。利用五種不同濃度之磷酸緩衝液，配合五種還原劑處理，均無法將C. amaranlticolor之單局部病斑囘接至木瓜，但以相同之處理囘接C. quinoa之單局部病斑卻可獲得成功，所選用之五種不同濃度之磷酸緩衝液中以0.025M之效果最佳，五種還原劑處理則以0.1%之Sodium diethyldithiocorbamate(DIECA)效果最好。C. quinoa之病斑出現後第六天罕一局劇了病斑內所含病毒濃度達到最高，囘接木瓜之成功率也最大。
利用上述方法已分離兩種產木瓜巨產生不同病徵之純系病毒(ptlre isolate)。其中病毒I可造成木瓜植株之餐凋，葉柄或莖幹彎曲下垂，葉子焦枯而全株死亡，病毒Ⅱ則不會造成植株萎凋而僅於葉部產生明顯之嵌紋病徵。除木瓜外二病毒之寄主範圍均僅限於藜科及葫蘆科之瓜類植物，其中尤以南瓜上之病徵二者只最有顯著之差異。
經比較二病毒之物理性質後發現，二者在耐熱性、耐冷凍陸、耐保存性、耐稀澤陸及沉降離心力上亦有明顯之不同。

並列摘要

Both Chenopodium amaranticolar and C. quinoa can be used as local lesion hosts for Papaya ringspot virus. None of the single lesions from C. amaranticolor can be re-inoculated to papaya seedlings by using 5 different concentration of phosphate buffer, pH 7.O, and 5 kinds of reducing agents, whereas the single lesion from C. quinoa can be successfully re-inoculated to papaya in the same experiment. Among the treatment, 0.025 M of phosphate buffer containing 0.1% Sodium diethyldithiocarbamate (DIECA) is the best combination for the re-inoculation of single lesion of C. quinoa to papaya. The maximum virus concentration of one single lesion of C. quinoa is 6 days after lesion appearance, this is also the best favorable stage for re-inoculation.
Following this procedures, we have obtained two isolates of Papaya ringspot virus which designated it as Virus Ⅰ and Virus Ⅱ. Virus Ⅰ can cause the papaya plant wilting, while Virus Ⅱ produces conspicuous mosaic only. The host ranges of these two isolates are both limited in Chenopodiaceae and Cucurbitaceae. Among the hosts, squash is the only one whose symptom caused by these two isolates is extremely different.
Thermoinactivation point of VirusⅠ is 45-50 c which is lower than that of Virus Ⅱ whose is 55-60 c. Dilution end point of Virus Ⅰ is 10^(-4)-10^(-5) but Virus Ⅱ is at 10^(-3)-10^(-4). Longevity in vitro of Virus Ⅰ is 10-11 days whereas Virus Ⅱ has only 7-8 days.
Freezing the crude sap of these two isolates at -30 c for 24 hr retains 12.5 % and 11.1 % infectivity for Virus Ⅰ and Ⅱ respectively.
Particles of Virus Ⅰcan all be scdimentated after centrifuging at 25000 rpm (48200g), while Virus Ⅱ needs 30000 rpm (69400g) for particle sedimentation.
According to the result, we consider that the causal agents of papaya vu-us disease in Taiwan may exist different strain or viruses, it needs further study to clarify this quesiton.