ISSN 1021-4437, Russian Journal of Plant Physiology, 2008, Vol. 55, No. 2, pp. 168–174. © Pleiades Publishing, Ltd., 2008.
Knocking out genes is the most frequently used
strategy to study the function of genes. Transfer-DNA
(T-DNA) and transposon tagging were predominantly
used for gene disruption in plants to provide novel
mutants. The antisense RNA (asRNA) technology is
another powerful tool for the study of gene functions.
But the limitations of these methods are obvious: they
are time- and labor-consuming methods and, in some
cases, gave unpredictable results. Virus-induced gene
silencing (VIGS), as a gene expression suppression
technique, was developed recently for identifying the
functions of plant genes. It is initiated when a recombi-
nant virus vector carrying a sequence of a host gene
infects the plant. The endogenous gene transcripts,
which are homologous to the inserts in the viral vector,
are degraded by post-transcriptional gene silencing
(PTGS) . VIGS circumvents plant transformation,
simpliﬁes methodology, and speeds the result obtain-
ing, as compared with three methods described above.
Therefore, VIGS becomes a new powerful tool for the
functional genomics and is now widely used for func-
tional gene characterization, in particular in
, tomato , barley
, legume , cassava , and others.
With the development of molecular biology and bio-
chemistry, the mechanism of VIGS is gradually clari-
ﬁed. Many novel VIGS vectors are developed for vari-
Abbreviations: dsRNA—double-stranded RNA; GFP—green ﬂu-
orescent protein gene; PDS—phytoene desaturase gene; PTGS—
post-transcriptional gene silencing; RDRP—RNA-dependent
RNA polymerase; RNAi—RNA interference; TRV—tobacco rat-
tle virus; VIGS—virus-induced gene silencing.
This text was submitted by the authors in English.
ous plant species, and new infection methods are tried
for different plant organs. In addition, some researches
also establish the new reporter system of VIGS. Our
review focuses on these recent advances.
THE MECHANISM OF VIGS
The essence of VIGS is that RNA silencing is trig-
gered by virus infection, which degrades viral tran-
scripts and transcripts of cognate nuclear genes .
VIGS is a member of RNA silencing family, which is
also known as PTGS in plants , quelling in fungi ,
and RNA interference (RNA
) in animals . Because
these phenomena have very similar mechanisms, the
name of RNA
is now used more frequently. In this
paper, the mechanism of VIGS is only discussed.
The presented model for the VIGS mechanism
(Fig. 1) includes three phases: triggering, signal ampli-
fying, and delivering. In the ﬁrst phase, double-
stranded RNA (dsRNA) is the triggering factor for gene
silencing. dsRNA is synthesized from a single-stranded
RNA (ssRNA) by an RNA-dependent RNA polymerase
(RDRP). Then, it is recognized by Dicer-like (DCL)
enzymes and degraded to 21
24-bp small interfering
RNAs (siRNAs) [11, 12].
The formation of dsRNA is diverse in different
viruses. In RNA viruses, viral RNA directly forms
dsRNA by viral RDRP. The dsRNA appears to enter the
pathway directly at the dsRNA step [13, 14]. However,
DNA viruses form dsRNA indirectly by an unknown
mechanism, which may involve aberrant RNAs
(aRNAs) . Recently, geminiviruses, which are
bipartite, single-stranded DNAs, probably use the same
pathway to form dsRNA, with the requirement of
Virus-Induced Gene Silencing in Plant Species
Y. Shao, H. L. Zhu, H. Q. Tian, X. G. Wang, X. J. Lin, B. Z. Zhu, Y. H. Xie, and Y. B Luo
Laboratory of Fruit Biology, College of Food Science and Nutritional Engineering, China Agricultural University,
PO Box 204, No. 17 Qinghua East Road, Haidian, Beijing, 100083 China;
fax: +86-10-6273-6479; e-mail: firstname.lastname@example.org
Received December 15, 2006
—As a method of post-transcriptional gene silencing (PTGS), virus-induced gene silencing (VIGS)
became a powerful tool for the study of gene function in plants. Current researches are focused on unraveling
the mechanisms of PTGS, ﬁnding novel viral vectors and new infection methods in order to broaden the host
species spectrum, and establishing the new reporter gene system of VIGS to demonstrate gene silencing, as well
as developing the high-throughput silencing for genomic scale research. The aim of this review is to bring
together recent advances of VIGS, an attractive method, for understanding it in the study of plants.
Key words: gene function - infection - plants - reporter gene - RNA
- VIGS - viral vector