Present address: Texas A&M Agricultural Experimental Station, 2415 E. Highway 83, Weslaco, TX 78596, USA.
Post-transcriptional silencing of a neomycin phosphotransferase II transgene correlates with the accumulation of unproductive RNAs and with increased cytosine methylation of 3′ flanking regions
Article first published online: 5 MAR 2002
The Plant Journal
Volume 12, Issue 2, pages 379–392, August 1997
How to Cite
Van Houdt, H., Ingelbrecht, I., Van Montagu, M. and Depicker, A. (1997), Post-transcriptional silencing of a neomycin phosphotransferase II transgene correlates with the accumulation of unproductive RNAs and with increased cytosine methylation of 3′ flanking regions. The Plant Journal, 12: 379–392. doi: 10.1046/j.1365-313X.1997.12020379.x
- Issue published online: 5 MAR 2002
- Article first published online: 5 MAR 2002
- Received 29 October 1996; revised 8 April 1997; accepted 8 April 1997.
- Cited By
The transgenic tobacco plant GVCHS(320)-1 harbours several T-DNAs with the neomycin phosphotransferase II (nptll)-encoding chimeric gene under control of the cauliflower mosaic virus 35S promoter (CaMV 35S). These T-DNAs are distributed over two loci, named A and B. The primary transformant GVCHS(320)-1 had substantially reduced steady-state nptll transcript levels due to the activity of a post-transcriptional silencing mechanism. Silencing of the nptll-encoding transgenes in the progeny of GVCHS(320)-1 requires the presence of the A locus that consists of two physically separated T-DNAs. Although the B locus contains three T-DNAs in the same orientation, it gives rise to high steady-state nptll mRNA levels and NPTII protein levels even in homozygous condition. The B locus only becomes silenced in trans in the presence of a silencing locus. The data suggest that silencing of the nptll transgenes is reinforced by ageing. It is also suggested that silencing is correlated with a reduced NPTII protein/nptll mRNA ratio, which may be interpreted as the accumulation of unproductive nptll RNA molecules in silenced plants. The data further demonstrate that the silenced state is correlated with extensive C-methylation of diagnostic sites in the 3′ three-quarters of the coding sequence and in the 3′ region up to 1400 bp downstream of the polyadenylation signal.