William Underwood,3 and
Sheng Yang He1,2,4
1Department of Plant Biology, Michigan State University, East Lansing 48824, U.S.A.; 2Department of Energy Plant Research Laboratory, Michigan State University, East Lansing; 3Energy Biosciences Institute, University of California, Berkeley 94720, U.S.A.; 4Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing
Go to article:
Accepted 2 April 2013.
The pleiotropic drug resistance (PDR) proteins belong to the super-family of ATP-binding cassette (ABC) transporters. AtPDR8, also called PEN3, is required for penetration resistance of Arabidopsis to nonadapted powdery mildew fungi. During fungal infection, plasma-membrane-localized PEN3 is concentrated at fungal entry sites, as part of the plant's focal immune response. Here, we show that the pen3 mutant is compromised in resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000. P. syringae pv. tomato DC3000 infection or treatment with a flagellin-derived peptide, flg22, induced strong focal accumulation of PEN3-green fluorescent protein. Interestingly, after an initial induction of PEN3 accumulation, P. syringae pv. tomato DC3000 but not the type-III-secretion-deficient mutant hrcC could suppress PEN3 accumulation. Moreover, transgenic overexpression of the P. syringae pv. tomato DC3000 effector AvrPto was sufficient to suppress PEN3 focal accumulation in response to flg22. Analyses of P. syringae pv. tomato DC3000 effector deletion mutants showed that individual effectors, including AvrPto, appear to be insufficient to suppress PEN3 accumulation when delivered by bacteria, suggesting a requirement for a combined action of multiple effectors. Collectively, our results indicate that PEN3 plays a positive role in plant resistance to a bacterial pathogen and show that focal accumulation of PEN3 protein may be a useful cellular response marker for the Arabidopsis–P. syringae interaction.
© 2013 The American Phytopathological Society