Phosphorylation of the Pseudomonas syringae effector AvrPto is required for FLS2/BAK1-independent virulence activity and recognition by tobacco |
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Authors: | Inhwa Yeam Hanh P Nguyen Gregory B Martin |
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Institution: | Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA;, Department of Plant Biology, Cornell University, Ithaca, NY 14853, USA;, and Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA |
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Abstract: | The type III effector protein AvrPto from Pseudomonas syringae pv. tomato is secreted into plant cells where it promotes bacterial growth and enhances symptoms of speck disease on susceptible tomato plants. The virulence activity of AvrPto is due, in part, to its interaction with components of host pattern recognition receptor complexes, which disrupts pathogen-associated molecular pattern-triggered immunity. This disruption mechanism requires a structural element of the AvrPto protein, the CD loop, which is also required for triggering Pto/Prf-mediated resistance in tomato. We have shown previously that the carboxyl-terminal domain (CTD) of AvrPto is phosphorylated and also contributes to bacterial virulence. Here we report that phosphorylation of the CTD on S147 and S149 promotes bacterial virulence in an FLS2/BAK1-independent manner, which is mechanistically distinct from the CD loop. In a striking corollary with Pto recognition of the CD loop in tomato, the tobacco species Nicotiana sylvestris and Nicotiana tabacum have a recognition mechanism that specifically detects the phosphorylation status of the CTD. Thus different species in the Solanaceae family have evolved distinct recognition mechanisms to monitor the same type III effector. |
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Keywords: | plant immunity resistance gene PAMPs PAMP-triggered immunity |
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