Plant Biotechnology Reports

, Volume 13, Issue 2, pp 193–199 | Cite as

Protein 2b of Cucumber mosaic virus strains IA and SD preferentially suppresses RDR6-dependent silencing pathway

  • Mayuko Shimokawa
  • Sayaka Hirai
  • Hiroaki KodamaEmail author
Short Communication


The 2b protein of Cucumber mosaic virus (CMV) subgroup IB strain IA (IA2b) suppresses the sense transgene-induced post-transcriptional gene silencing (S-PTGS) but not the inverted repeat-induced post-transcriptional gene silencing (IR-PTGS) of a tobacco microsome-localized α-linolenate synthase gene (NtFAD3). In contrast, the 2b protein of CMV subgroup IB strain SD (SD2b) has been reported to suppress IR-PTGS. We overexpressed the SD2b gene in tobacco, and this transgenic line was crossed with the transgenic plants showing S-PTGS and IR-PTGS of the NtFAD3 gene. The phenotype of offspring showed that SD2b inhibited S-PTGS but not IR-PTGS. Next, we determined the suppressor activity of IA2b and SD2b proteins in a transient IR-PTGS assay. The transient expression of firefly luciferase (LUC) gene was efficiently decreased by IR-PTGS. Co-infiltration of SD2b and IA2b gene partially suppressed IR-PTGS of the LUC gene in the wild-type plants; however, these 2b proteins did not suppress IR-PTGS in the RNA-dependent RNA polymerase6 (RDR6) knockdown plants. It has been reported that RDR6-dependent secondary small interfering RNA synthesis does not occur in the IR-PTGS, when targeting endogenous genes such as NtFAD3, but is efficiently induced in the IR-PTGS of the reporter transgenes. These results indicate that the SD2b and IA2b preferentially suppress the RDR6-dependent silencing pathway but do not suppress the RDR6-independent IR-PTGS pathway.


Agroinfiltration Cucumber mosaic virus 2b protein IR-PTGS RDR6 S-PTGS Secondary siRNA synthesis 



The authors would like to thank Enago ( for the English language review.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflicts of interest.

Supplementary material

11816_2019_520_MOESM1_ESM.docx (121 kb)
Supplementary material 1 (DOCX 122 KB)


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Copyright information

© Korean Society for Plant Biotechnology 2019

Authors and Affiliations

  1. 1.Graduate School of HorticultureChiba UniversityMatsudoJapan

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