title: Epigenetic silencing in transgenic plants.
abstract: Epigenetic silencing is a natural phenomenon in which the expression of genes is regulated through modifications of DNA, RNA, or histone proteins. It is a mechanism for defending host genomes against the effects of transposable elements and viral infection, and acts as a modulator of expression of duplicated gene family members and as a silencer of transgenes. A major breakthrough in understanding the mechanism of epigenetic silencing was the discovery of silencing in transgenic tobacco plants due to the interaction between two homologous promoters. The molecular mechanism of epigenetic mechanism is highly complicated and it is not completely understood yet. Two different molecular routes have been proposed for this, that is, transcriptional gene silencing, which is associated with heavy methylation of promoter regions and blocks the transcription of transgenes, and post-transcriptional gene silencing (PTGS), the basic mechanism is degradation of the cytosolic mRNA of transgenes or endogenous genes. Undesired transgene silencing is of major concern in the transgenic technologies used in crop improvement. A complete understanding of this phenomenon will be very useful for transgenic applications, where silencing of specific genes is required. The current status of epigenetic silencing in transgenic technology is discussed and summarized in this mini-review.
authors.affiliation: Molecular Plant Biology and Biotechnology Division, Central Institute of Medicinal and Aromatic Plants Research Centre, Bangalore India.
authors.forename: Sarma
authors.initials: S
authors.lastname: Rajeevkumar
authors.affiliation: Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore India.
authors.forename: Pushpanathan
authors.initials: P
authors.lastname: Anunanthini
authors.affiliation: Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar University, Coimbatore India.
authors.forename: Ramalingam
authors.initials: R
authors.lastname: Sathishkumar
keywords: homology-dependent gene silencing; post-transcriptional gene silencing; systematic acquired silencing; transcriptional gene silencing; transgenic plants