Plant Molecular Biology

, Volume 60, Issue 3, pp 423–435

Lower Levels of Transgene Silencing in Roots is Associated with Reduced DNA Methylation Levels at Non-Symmetrical Sites but not at Symmetrical Sites

  • Ida Bagus Andika
  • Hideki Kondo
  • Muhammad Danial Rahim
  • Tetsuo Tamada
Article

DOI: 10.1007/s11103-005-4429-7

Cite this article as:
Andika, I.B., Kondo, H., Rahim, M.D. et al. Plant Mol Biol (2006) 60: 423. doi:10.1007/s11103-005-4429-7
  • 116 Downloads

Abstract

Transgene transcripts were recently shown to accumulate at higher levels in roots, relative to leaves, of silenced-transgenic Nicotiana benthamiana plants and to be inversely related with the accumulation of small interfering RNAs (siRNAs), suggesting that RNA silencing is less active in roots than in leaves (Andika et al., 2005. Mol. Plant–Microbe Interact. 18: 194). Here we show that the lower transgene RNA silencing activity in roots was associated with lower transgene methylation levels at non-symmetrical CpNpN context but not at symmetrical CpG or CpNpG context in three sets of transformant plants with different exogenous genes. In contrast, such a difference between roots and leaves was not observed for the Tnt1 retrotransposon: no Tnt1 transcript was detected in roots or in leaves of N. benthamiana, while equal levels of Tnt1-derived siRNA accumulation and Tnt1 methylation were found. From our data and previously reported information, we suggest that roots have less of an activity that acts at the step of generation of siRNAs.

Key words

DNA methylationRNA silencingroot tissuetransposon silencing

Abbreviations

BNYVV

Beet necrotic yellow vein virus

C

cytosine

DIG

digoxigenin

dsRNA

double-stranded RNA

GFP

green fluorescent protein

LTR

long terminal repeat

Nos

nopaline synthase

ORF

open reading frame

PTGS

post-transcriptional gene silencing

RdDM

RNA-directed DNA methylation

RdRP

RNA-dependent RNA polymerase

RNAi

RNA interfering

RTD

readthrough domain

siRNA

small interfering RNA

VIGS

virus-induced gene silencing

Copyright information

© Springer 2006

Authors and Affiliations

  • Ida Bagus Andika
    • 1
  • Hideki Kondo
    • 1
  • Muhammad Danial Rahim
    • 1
  • Tetsuo Tamada
    • 1
  1. 1.Research Institute for BioresourcesOkayama UniversityKurashikiJapan