Sarmiento Cecilia, Gomez Eva, Meier Merike, Kavanagh Tony A, Truve Erkki
Tallinn University of Technology, Department of Gene Technology, Akadeemia tee 15, 19086 Tallinn, Estonia.
Virus Res. 2007 Jan;123(1):95-9. doi: 10.1016/j.virusres.2006.07.013. Epub 2006 Sep 12.
The Sobemovirus genome consists of positive sense, single-stranded polycistronic RNA. The 5'-terminal ORF, encoding the protein P1, is its most variable region. Sobemoviral P1 has been described as dispensable for replication but indispensable for systemic infection. The P1 of Rice yellow mottle virus-Nigerian isolate (RYMV-N) is the only RNA silencing suppressor reported for sobemoviruses until now. Using an agrobacterium-mediated transient assay, we demonstrate here that P1 of Cocksfoot mottle virus-Norwegian isolate (CfMV-NO) suppresses RNA silencing in Nicotiana benthamiana and Nicotiana tabacum, two non-host plants. CfMV-NO P1 was able to suppress the initiation and maintenance of silencing. The suppression of systemic silencing was weaker with CfMV-NO P1 than in the case of RYMV-N P1. In the case of suppression at the local level, the reduction in the amount of 25-nucleotide small interfering RNAs (siRNAs) was less pronounced for CfMV-NO P1 than it was when RYMV-N P1 was used. At the same time, we show that CfMV-NO P1 did not bind siRNAs.
南方菜豆花叶病毒属病毒基因组由正义单链多顺反子RNA组成。编码蛋白P1的5'端开放阅读框是其最可变的区域。南方菜豆花叶病毒属病毒的P1已被描述为复制非必需，但系统感染必需。直到现在，水稻黄斑驳病毒尼日利亚分离株（RYMV-N）的P1是南方菜豆花叶病毒属病毒中唯一报道的RNA沉默抑制子。利用农杆菌介导的瞬时分析，我们在此证明鸭茅斑驳病毒挪威分离株（CfMV-NO）的P1在两种非寄主植物本氏烟草和烟草中抑制RNA沉默。CfMV-NO P1能够抑制沉默的起始和维持。CfMV-NO P1对系统沉默的抑制作用比RYMV-N P1弱。在局部水平抑制的情况下，CfMV-NO P1使25个核苷酸的小干扰RNA（siRNA）量减少的程度不如使用RYMV-N P1时明显。同时，我们表明CfMV-NO P1不结合siRNA。
