The important role of DNA methylation,histone code,RNA-mediated gene silencing,and the pcG complex in plant development and gene expression,the relationship between them,were mainly demonstrated.

The term virus-induced gene silencing (VIGS) was first used to describe the phenomenon of recovery from virus infection, a natural plant antiviral mechanism, which recently has been exploited as a genetic technique involving recombinant viruses with a target gene fragment insert to knock down expression of endogenous target genes, and thereby analyse gene functions.

The results showed that gusA could be silenced in leaves,flowers,fruits,branches,stems and the points between branch and stem of tomato by virus-induced gene silencing.

For virus induced gene silencing (VIGS), it is induced by infecting a plant with a plant virus that has had its genome modified to include a sequence identical to that in RNA transcribed from the host gene to be silenced.

In this review, the current progress on identification of the new antibiotics through silent gene activation was elucidated and the successful development of two antibiotics, MM2002 (angucyclines) and notinorhodin using the silent gene activation technique, was discussed in detail.

Gene targeting in livestock fibroblasts has proven extremely difficult to achieve, particularly on silent gene locus.