Tobacco mosaic virus replicase-auxin/indole acetic acid protein interactions: reprogramming the auxin response pathway to enhance virus infection.
The replicase protein of Tobacco mosaic virus (TMV) disrupts the localization and stability of interacting auxin/indole acetic acid (Aux/IAA) proteins in Arabidopsis, altering auxin-mediated gene regulation and promoting disease development (M. S. Padmanabhan, S. P. Goregaoker, S. Golem, H. Shiferaw, and J. N. Culver, J. Virol. 79:2549-2558, 2005). In this study, a similar replicase-Aux/IAA interaction affecting disease development was identified in tomato. The ability of the TMV replicase to interact with Aux/IAA proteins from diverse hosts suggests that these interactions contribute to the infection process. To examine the role of this interaction in virus pathogenicity, the replication and spread of a TMV mutant with a reduced ability to interact with specific Aux/IAA proteins were examined. Within young (4- to 6-week-old) leaf tissue, there were no significant differences in the abilities of Aux/IAA-interacting or -noninteracting viruses to replicate and spread. In contrast, in mature (10- to 12-week-old) leaf tissue, the inability to interact with specific Aux/IAA proteins correlated with a significant reduction in virus accumulation. Correspondingly, interacting Aux/IAA levels are significantly higher in older tissue and the overaccumulation of a degradation-resistant Aux/IAA protein reduced virus accumulation in young leaf tissue. Combined, these findings suggest that TMV replicase-Aux/IAA interactions selectively enhance virus pathogenicity in tissues where Aux/IAA proteins accumulate. We speculate that the virus disrupts Aux/IAA functions as a means to reprogram the cellular environment of older cells to one that is more compatible for virus replication and spread.
Padmanabhan
Meenu S
MS
Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, MD 20742, USA.
Kramer
Sabrina R
SR
Wang
Xiao
X
Culver
James N
JN
D001483:Base Sequence; D017931:DNA Primers; D007210:Indoleacetic Acids / Q000378:metabolism*; D010935:Plant Diseases; D030821:Plants, Genetically Modified; D011485:Protein Binding; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D014027:Tobacco Mosaic Virus / Q000201:enzymology*
D017931:DNA Primers; D007210:Indoleacetic Acids; C030737:indoleacetic acid; D012324:RNA-Dependent RNA Polymerase