University of Arkansas, Fayetteville Division of Agriculture


RNA interference (RNAi), a pathway capable of silencing genes, has until recently only been achievable in the laboratory by the use of one method, expression of inverted repeat sequences of DNA. These constructs generate a double-stranded RNA, which in turn induce post-transcriptional silencing of other genes that bear sequence homology with the transgene. This approach of targeted gene silencing is extremely useful for studying the function of genes and engineering new traits in both plants and animals. It has recently been discovered that a transgene lacking the polyadenylation signal, called a truncated transgene, is also capable of inducing RNAi in plant cells. This technique was used in efficiently silencing two genes of Arabidopsis thaliana, the Phytochrome A (PHYA) and Phytochrome B (PHY B) genes; however, the effectiveness of this method on a broader range of genes is unknown. The purpose of this study is to analyze the effect of truncated-transgene expression on the homologous native genes in the Arabidopsis genome. More specifically, the rate of silencing of three genes, Variegated 2 (VAR2), Brassinosteroid Insensitive 1 (BRI1) and Apetala 1 (AP1) due to the expression of truncated VAR2, BRI1, and AP1 transgenes, respectively, in Arabidopsis thaliana was examined. This experiment provided important data for assessing the efficacy of truncated transgene based gene silencing system for plants.