http://www.abbs.info E-mail: [email protected]
ISSN
1672-9145
Acta Biochim Biophys Sin
2005, 37(4): 248–253
CN 31-1940/Q
A Viral Protein Suppresses siRNA-directed Interference in Tobacco
Mosaic Virus Infection
Ming-Min ZHAO, De-Rong AN*,
Guang-Hua HUANG1, Zu-Hua HE2, and Jiang-Ye CHEN1*
College of Plant
Protection, North West Science and Technology University of Agriculture and
Forestry, Shaanxi 712100, China;
1State Key Laboratory of
Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai
Institutes for Biological Sciences,
Chinese Academy of
Sciences, Shanghai 200031, China; 2State Key Laboratory of Plant Molecular Genetics,
Institute of Plant Physiology and Ecology,
Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai
200032, China
Abstract Plant viruses encode
suppressors of post-transcriptional
gene silencing (PTGS), an adaptive defense response that limits virus
replication and its spread in plants. The helper component proteinase (HC-Pro)
of the potato virus A (PVA, genus Potyvirus) suppresses PTGS of
silenced transgenes. Here, the effect of HC-Pro on siRNA-directed interference
in the tobacco mosaic virus (TMV) was examined by using a transient Agrobacterium
tumefaciens-based delivery system in intact tissues. It was shown that the
interference effect was completely blocked by co-infiltration with HC-Pro plus
siRNA constructs in both systemic and hypersensitive hosts. In the system host,
all plants agro-infiltrated with HC-Pro plus siRNA constructs displayed the
same symptoms as the negative control. Meanwhile, TMV RNA accumulation was found
to be abundant in the upper leaves using reverse transcriptase-PCR (RT-PCR) and Northern blot assays. On
the contrary, plants agro-infiltrated with the siRNA construct alone were free
of symptoms. Therefore, our study suggests that the transient expression of
HC-Pro inhibited the siRNA-directed host defenses against TMV infection.
Key words siRNA; HC-Pro; tobacco mosaic virus;
suppressor
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Received: January 4, 2005 Accepted: March 1, 2005
This study was supported by the grants from the Ministry of Science
and Technology of China (No. 100C26216101344) and the State Key Laboratory of
Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences
*Corresponding authors:
De-Rong AN: Tel, 86-29-87092728; Fax, 86-29-87092401/13032921115;
E-mail, [email protected]
Jiang-Ye CHEN: Tel, 86-21-54921251; Fax, 86-21-64338357; E-mail, [email protected]