Present address: Department of Pathology, University of Michigan Medical School, 1500 E. Medical Center Drive, 4131 CCGC, Ann Arbor, MI 48109, USA
A functional genetic assay for nuclear trafficking in plants
Article first published online: 5 MAR 2007
The Plant Journal
Volume 50, Issue 1, pages 149–158, April 2007
How to Cite
Kanneganti, T.-D., Bai, X., Tsai, C.-W., Win, J., Meulia, T., Goodin, M., Kamoun, S. and Hogenhout, S. A. (2007), A functional genetic assay for nuclear trafficking in plants. The Plant Journal, 50: 149–158. doi: 10.1111/j.1365-313X.2007.03029.x
- Issue published online: 5 MAR 2007
- Article first published online: 5 MAR 2007
- Received 26 September 2006; revised 17 November 2006; accepted 21 November 2006.
- plant pathogen;
- nuclear import;
The receptor importin-α mediates the nuclear import of functionally diverse cargo proteins that contain arginine/lysine-rich nuclear localization signals (NLSs). Functional homologs of importin-α have been characterized in a wide range of species including yeast, human and plants. However, the differential cargo selectivity of plant importin-α homologs has not been established. To advance nuclear import studies conducted in plant cells, we have developed a method that allows importin-α-dependent nuclear import to be assayed in Nicotiana benthamiana. We employed virus-induced gene silencing (VIGS) to knock down the expression of two importin-α homologs, NbImpα1 and NbImpα2, which we identified from N. benthamiana. Agro-infiltration was then used to transiently express the NLS-containing proteins Arabidopsis thaliana fibrillarin 1 (AtFib1) and the Nuk6, Nuk7 and Nuk12 candidate effector proteins of the oomycete plant pathogen Phytophthora infestans. In this manner, we demonstrate importin-α-dependent nuclear import of Nuk6 and Nuk7. In contrast, the nuclear import of Nuk12 and AtFib1 was unaffected in cells of NbImpα-silenced plants. These data suggest that P. infestans Nuk6 and Nuk7 proteins are dependent on one or more α-importins for nuclear import. Our VIGS-based assay represents a powerful new technique to study mechanisms underlying the transport of proteins from cytoplasm to nucleus in plants.