Down-Regulation of the 26S Proteasome Subunit RPN9 Inhibits Viral Systemic Transport and Alters Plant Vascular Development
Open Access
- 18 August 2006
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 142 (2), 651-661
- https://doi.org/10.1104/pp.106.083519
Abstract
Plant viruses utilize the vascular system for systemic movement. The plant vascular network also transports water, photosynthates, and signaling molecules and is essential for plant growth. However, the molecular mechanisms governing vascular development and patterning are still largely unknown. From viral transport suppressor screening using virus-induced gene silencing, we identified a 26S proteasome subunit, RPN9, which is required for broad-spectrum viral systemic transport. Silencing of RPN9 in Nicotiana benthamiana inhibits systemic spread of two taxonomically distinct viruses, Tobacco mosaic virus and Turnip mosaic virus. The 26S proteasome is a highly conserved eukaryotic protease complex controlling many fundamental biochemical processes, but the functions of many 26S proteasome regulatory subunits, especially in plants, are still poorly understood. We demonstrate that the inhibition of viral systemic transport after RPN9 silencing is largely due to alterations in the vascular tissue. RPN9-silenced plants display extra leaf vein formation with increased xylem and decreased phloem. We further illustrate that RPN9 functions at least in part through regulation of auxin transport and brassinosteroid signaling, two processes that are crucial for vascular formation. We propose that RPN9 regulates vascular formation by targeting a subset of regulatory proteins for degradation. The brassinosteroid-signaling protein BZR1 is one of the targets.Keywords
This publication has 82 references indexed in Scilit:
- The negative regulator of plant cold responses, HOS1, is a RING E3 ligase that mediates the ubiquitination and degradation of ICE1Proceedings of the National Academy of Sciences of the United States of America, 2006
- Control of leaf vascular patterning by polar auxin transportGenes & Development, 2006
- Plant virus transport: motions of functional equivalenceTrends in Plant Science, 2005
- BRL1 and BRL3 are novel brassinosteroid receptors that function in vascular differentiation inArabidopsisDevelopment, 2004
- Interdependency of Brassinosteroid and Auxin Signaling in ArabidopsisPLoS Biology, 2004
- Brassinosteroids Interact with Auxin to Promote Lateral Root Development in ArabidopsisPlant Physiology, 2004
- Cell Polarity and PIN Protein Positioning in Arabidopsis Require STEROL METHYLTRANSFERASE1 FunctionPlant Cell, 2003
- Plasmodesmata: Gatekeepers for Cell-to-Cell Transport of Developmental Signals in PlantsAnnual Review of Cell and Developmental Biology, 2000
- Auxin Is Required for Leaf Vein Pattern in ArabidopsisPlant Physiology, 1999
- Phloem transport: Are you chaperoned?Current Biology, 1999