A protein phosphatase 2C, responsive to the bacterial effector AvrRpm1 but not to the AvrB effector, regulates defense responses in Arabidopsis
Article first published online: 13 NOV 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
The Plant Journal
Volume 61, Issue 2, pages 249–258, January 2010
How to Cite
Widjaja, I., Lassowskat, I., Bethke, G., Eschen-Lippold, L., Long, H.-H., Naumann, K., Dangl, J. L., Scheel, D. and Lee, J. (2010), A protein phosphatase 2C, responsive to the bacterial effector AvrRpm1 but not to the AvrB effector, regulates defense responses in Arabidopsis. The Plant Journal, 61: 249–258. doi: 10.1111/j.1365-313X.2009.04047.x
- Issue published online: 8 JAN 2010
- Article first published online: 13 NOV 2009
- Received 27 November 2008; revised 22 September 2009; accepted 5 October 2009; published online 13 November 2009.
- salicylic acid;
- Pseudomonas syringae;
- disease resistance
Using a proteomics approach, a PP2C-type phosphatase (renamed PIA1, for PP2C induced by AvrRpm1) was identified that accumulates following infection by Pseudomonas syringae expressing the type III effector AvrRpm1, and subsequent activation of the corresponding plant NB-LRR disease resistance protein RPM1. No accumulation of PIA1 protein was seen following infection with P. syringae expressing AvrB, another type III effector that also activates RPM1, although PIA transcripts were observed. Accordingly, mutation of PIA1 resulted in enhanced RPM1 function in response to P. syringae pathover tomato (Pto) DC3000 (avrRpm1) but not to Pto DC3000 (avrB). Thus, PIA1 is a protein marker that distinguishes AvrRpm1- and AvrB-dependent activation of RPM1. AvrRpm1-induced expression of the pathogenesis-related genes PR1, PR2 and PR3, and salicylic acid accumulation were reduced in two pia1 mutants. By contrast, expression of other defense-related genes, including PR5 and PDF1.2 (plant defensin), was elevated in unchallenged pia1 mutants. Hence, PIA1 is required for AvrRpm1-induced responses, and confers dual (both positive and negative) regulation of defense gene expression.