Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: June 8, 2005
Publication Date: June 12, 2005
Citation: Cazzonelli, C.I., Velten, J.P. 2005. The effects of viral suppressor proteins and dsRNA on PTGS of different reporter genes in nicotiana species [abstract]. 5th Biennial Meeting on Post-Transcriptional Regulation of Plant Gene Expression, June 8-12, 2005, Austin, Texas. 5:28. Technical Abstract: In plants, posttranscriptional gene silencing (PTGS) is a highly conserved nucleotide sequence-specific RNA turnover mechanism that can recognize foreign RNA molecules and lead to the double stranded RNA-dependent silencing of transgenes. The mechanism(s) by which plants detect aberrant or foreign gene expression and trigger post-transcriptional gene silencing remains to be elucidated. An Agrobacteria-mediated in vivo transient assay system was established in tobacco (Nicotiana tobacum and benthamiana ) that allowed quantification of the effects of viral suppressor proteins (AC2, p19 and HcPro) and excess amounts of dsRNA on the PTGS of transiently and/or stably expressed reporter genes (e.g. firefly luciferase from Photinus pyralis, sea pansy luciferase from Renilla reniformis, green fluorescent from Aequorea victoria, '-glucuronidase from Escherichia coli and Myb-anthocyanin from Arabidopsis thaliana) . Our results support the hypothesis of aberrant RNA, rather then a threshold trigger for PTGS. The sequence identity/secondary structure of the reporter gene transcript appears to be a significant determinant of how the foreign transcript is perceived and PTGS is triggered and or maintained. In addition, we have observed "cross talk" between silencing of co-expressed reporter genes, possibly the result of a saturation of the PTGS pathway by overproduction of dsRNA.