Transgene‐induced gene silencing in plants

Downregulation of Caffeic Acid 3-O-Methyltransferase and Caffeoyl CoA 3-O-Methyltransferase in Transgenic Alfalfa: Impacts on Lignin Structure and Implications for the Biosynthesis of G and S Lignin

“…Reduction of enzymatic activity resulting from reduced transcript levels in plants expressing gene constructs in the sense orientation is characteristic of epigenetic gene silencing, which may occur at the transcriptional or post-transcriptional level (Vaucheret et al, 1998). To determine the basis for the reduced COMT and CCOMT activities in some of the sense transgenic lines, nuclear run-on transcription analyses were performed with transcripts completed in vitro from nuclei isolated from empty vector and COMT or CCOMT downregulated sense lines.…”

RNA interference acts as a natural antiviral response to O'nyong-nyong virus ( Alphavirus ; Togaviridae) infection of Anopheles gambiae

“…RNAi is a potent intracellular response activated by doublestranded RNA (dsRNA) and results in a reduced steady-state level of specific RNA molecules with sequence similarity to the dsRNA (2,3). The mechanism of RNAi has been studied in some detail in Drosophila melanogaster.…”

Insect Resistance in Transgenic Chrysanthemum [Dendranthema * grandiflorum (Ramat.) Kitamura] by the Introduction of a Modified .DELTA.-endotoxin Gene of Bacillus thuringiensis

“…Moreover, when EHA101 was used for infection, one to 3 copies of the transgene were introduced into the plant genome, while in the case of LBA4404, only one copy was introduced into the plant genome. Transgene inactivation (silencing) has been reported in several plant species and some models have been proposed for transcriptional and post-transcriptional silencing (Vaucheret et al 1998). Transgene can undergo transcriptional silencing when single or multiple copies are integrated into a locus located next to silent hypermethylated genomic sequences (position effect), and it has also been suggested that the large discrepancy between the DNA composition of the transgene and that of the surrounding genomic sequences leads to the specific methylation and inactivation of a foreign sequence.…”