Open AccessDisruption of Two Defensive Signaling Pathways by a Viral RNA Silencing Suppressor
Author(s) -
Mathew G. Lewsey,
Alex M. Murphy,
Dan MacLean,
Neil Dalchau,
Jack H. Westwood,
Keith Macaulay,
Mark H. Bennett,
Michaël Moulin,
David E. Hanke,
Glen Powell,
Alison G. Smith,
John P. Carr
Publication year - 2010
Publication title -
molecular plant-microbe interactions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.565
H-Index - 153
eISSN - 1943-7706
pISSN - 0894-0282
DOI - 10.1094/mpmi-23-7-0835
Subject(s) - biology , cucumber mosaic virus , jasmonic acid , gene silencing , arabidopsis , arabidopsis thaliana , gene , rna silencing , cucumovirus , rna interference , salicylic acid , gene expression , plant defense against herbivory , microbiology and biotechnology , mutant , rna , genetics
The Cucumber mosaic virus (CMV) 2b counter-defense protein disrupts plant antiviral mechanisms mediated by RNA silencing and salicylic acid (SA). We used microarrays to investigate defensive gene expression in 2b-transgenic Arabidopsis thaliana plants. Surprisingly, 2b inhibited expression of few SA-regulated genes and, in some instances, enhanced the effect of SA on certain genes. Strikingly, the 2b protein inhibited changes in the expression of 90% of genes regulated by jasmonic acid (JA). Consistent with this, infection of plants with CMV, but not the 2b gene-deletion mutant CMVΔ2b, strongly inhibited JA-inducible gene expression. JA levels were unaffected by infection with either CMV or CMVΔ2b. Although the CMV–Arabidopsis interaction is a compatible one, SA accumulation, usually considered to be an indicator of plant resistance, was increased in CMV-infected plants but not in CMVΔ2b-infected plants. Thus, the 2b protein inhibits JA signaling at a step downstream of JA biosynthesis but it primes induction of SA biosynthesis by another CMV gene product or by the process of infection itself. Like many plant viruses, CMV is aphid transmitted. JA is important in plant defense against insects. This raises the possibility that disruption of JA-mediated gene expression by the 2b protein may influence CMV transmission by aphids.