| Shandong is one of the largest peanut producing province with annual planting area of about 867 000 acres. Viral diseases cause great yield and economic losses to peanut production every year.We collected 153 peanut samples showing virus-like symptoms in 2008 and 2009 and detected for virus presence by RT-PCR. Totally three viruses were detected, ie Peanut stripe virus (PStV), Cucumber mosaic virus (CMV) and Peanut mottle virus (PeMoV). PStV was the most common virus and detected in every district of Shandong. PStV and CMV were detected from 48.4% and 19.0% of the samples, respectively. They co-existed in 9.2% of the samples. However, PeMoV only occurred in Qingdao.The 3′-terminal 1082 nucleotides (nt) of 74 PStV isolates were sequenced. The resultant sequences included 129 nt encoding partial NIb, 864 bp encoding coat protein (CP), and 89 nt of 3′-untranslated region. The CP genes of these 74 PStV isolates shared identities of 98.0%~100% and 98.3% ~100% at nt and amino acid (aa) levels, and shared 93.5%~100% nt identities and 92.0%~100% aa identities with those of other 36 PStV isolates available in the GenBank. These 110 isolates were clustered into two geographical origin-specific groups: isolates from mainland China, Indonesia and USA formed Group I, while those from Taiwan, Thailand and Viet Nam formed group II. Group I could be further divided into two subgroups- isolates from mainland China, USA and one from Africa formed subgroup IA, those from Indonesia formed subgroup IB. Population statistics analysis showed that the gene flow of PStV populations within a county was frequent, but that of PStV populations between countries was infrequent. PStV population of China is new emergent and the PStV population as a whole is in a state of expansion.A RNAi plant expression vector targeting PeMoV, CMV and PStV was constructed.Ten proteins of Potato virus Y (PVY) were successful expressed in E. coli, which lay foundation for the study of protein function and crystal structure.
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