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ISSN 1672-9145 Acta Biochim Biophys Sin 2005, 37(1): 25–31 CN 31-1940/Q

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Interaction between a Nanovirus-like Component and the Tobacco Curly Shoot Virus/Satellite Complex

Pei-Jun WU and Xue-Ping ZHOU*

Institute of Biotechnology, Zhejiang University, Hangzhou 310029, China

Abstract The biological role of DNA1, a nanovirus-like component shown to be associated with the begomovirus/satellite complex, has not yet been identified. Here, we demonstrated that DNA1 of Tobacco curly shoot virus isolate Y35 (TbCSV-Y35) attenuated leaf-curling symptoms induced by TbCSV-Y35 or TbCSV-Y35 plus Y35 DNAb in the early stage of symptom development and induced leaf cluster at a later stage of symptom development in Nicotiana benthamiana plants. The leaf disc assay demonstrated that TbCSV-Y35 DNA1 replicated autonomously. Southern blot analysis revealed that TbCSV-Y35 DNA1 reduced viral DNA accumulation. Viral DNA accumulation was not reduced when plants were co-inoculated with TbCSV-Y35 DNAb, but the TbCSV-Y35 DNAb level was dramatically reduced in the presence of TbCSV-Y35 DNA1. To determine whether the interaction between TbCSV/satellite complex and DNA1 had isolate specificity, DNA1 of TbCSV isolate Y132 was cloned and sequenced. It was found to have 75% nucleotide sequence identity with TbCSV-Y35 DNA1. Infectivity tests showed that TbCSV-Y132 DNA1 had no effect on the symptoms induced by TbCSV-Y35 or TbCSV-Y35 and Y35 DNAb in N. benthamiana plants, although Y132 DNA1 could replicate in these plants.

Key words Tobacco curly shoot virus; DNA1; DNAb; symptom; replication; interaction

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Received: September 24, 2004 Accepted: November 18, 2004

This work was supported by the grants from the National Out standing Youth Foundation (No. 30125032) and the National Natural Science Foundation of China (No. 30370927)

*Corresponding author: Tel, 86-571-86971680; Fax, 86-571-86971498; E-mail, [email protected]