JXB Advance Access published online on August 13, 2008
Journal of Experimental Botany, doi:10.1093/jxb/ern205
REVIEW-ARTICLE |
Focal accumulation of defences at sites of fungal pathogen attack
1Energy Biosciences Institute, 130 Calvin Hall, Mail Code 5230, University of California, Berkeley, CA 94720, USA
2Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
* To whom correspondence should be addressed. E-mail: ssomerville{at}berkeley.edu
Plants resist attack by haustorium-forming biotrophic and hemi-biotrophic fungi through fortification of the cell wall to prevent penetration through the wall and the subsequent establishment of haustorial feeding structures by the fungus. While the existence of cell wall-based defences has been known for many years, only recently have the molecular components contributing to such defences been identified. Forward genetic screens identified Arabidopsis mutants impaired in penetration resistance to powdery mildew fungi that were normally halted at the cell wall. Several loci contributing to penetration resistance have been identified and a common feature is the striking focal accumulation of proteins associated with penetration resistance at sites of interaction with fungal appressoria and penetration pegs. The focal accumulation of defence-related proteins and the deposition of cell wall reinforcements at sites of attempted fungal penetration represent an example of cell polarization and raise many questions of relevance, not only to plant pathology but also to general cell biology.
Key words: Actin, disease resistance, immunity, MLO, papilla, PEN1, PEN2, PEN3, powdery mildew
Received 22 May 2008; Revised 15 July 2008 Accepted 15 July 2008