Poster: Transcription Regulation

Abs # 1035: Interactions between post-transcriptional and transcriptional silencing pathways in arabidopsis thaliana > pathways in Arabidopsis thaliana

Presenter:	Callaway, Anton S, anton@unity.ncsu.edu
Authors	Callaway, Anton S (A)   Jones, Lindsay  (A)   Sowinski, Dolores A (A)   Thompson, William F (A)   Allen, George C (A)
Affiliations:	(A): North Carolina State University

Gene silencing has a profound impact on the net level of transgene expression. Gene silencing has been operationally divided into two major forms: transcriptional gene silencing (TGS) whereby transcription initiation of the gene is blocked and post-transcriptional gene silencing (PTGS) which is manifested through the degradation of transcripts from the gene. Recent genetic data using silencing mutants of Arabidopsis thaliana suggest that these two silencing mechanisms are not entirely independent. Our study explores the interactions between TGS and PTGS using populations of transgenic Arabidopsis lines transformed with an intron-bearing luciferase reporter gene driven by either the CaMV 35S promoter or the octopine synthase promoter. The expression cassettes are either flanked by copies of the RB7 matrix attachment region (MAR) or not. The presence of flanking RB7 MARs has been shown to reduce gene silencing in transgenic plants. Our experiments are designed to test the hypothesis that transgenes initiating abundant transcript synthesis (e.g. driven by strong promoters and flanked by MARs) are more likely to be silenced at the post-transcriptional level than when transcript production is low. We are also comparing expression patterns at different developmental stages to determine when silencing occurs and following expression through several meiotic generations to assess the effect of MARs on the stability of transgene expression.