Yurko, Nathan , Teitzel, Gail M. , Crk, Tanja , Wroblewski, Tadeusz , Michelmore, Richard , Greenberg, Jean T. .
A Study of Interactions Between Pseudomonas syringae, Effectors, and Lettuce.
The plant pathogen Pseudomonas syringae injects proteins known as effectors into the plant cells using a type III secretion system to better enable infection. These effectors aid in bacterial pathogenesis, but sometimes are recognized by the host plant and elicit a hypersensitive response, a form of programmed cell death that serves to restrict the growth of the pathogen. The roles of most effectors are only known in the context of a few host plants. Our goal is to expand the information on the role of effectors in the infection process and host range restriction on different crop species. Here we focused on the role of several effectors in lettuce infections. We have used the ability of an effector to induce cell death on lettuce as a possible indication that the effector is recognized by a particular cultivar. Several P. syringae effectors can induce cell death on one or more cultivars of lettuce (Mariska, Valmaine, and Ninja) when introduced via Agrobacterium tumefaciens. To test the role of these effectors in host range restriction and/or virulence, we created transgenic P. syringae strains of a disease-causing isolate (P. syrinage pv. alisalensis BS228) expressing cell death effectors cloned from other P. syringae strains. Inoculation of these strains into lettuce revealed that AvrRpt2 can dramatically restrict the growth and symptoms of BS228 on all lettuce cultivars tested, whereas AvrB and AvrRps4 did not significantly alter the disease caused by BS228 compared to inoculations with strains carrying a control vector. Liquid growth curves confirmed that the transgenic bacteria grow at approximately the same rate in vitro as wildtype. These results indicate that lettuce can recognize AvrRpt2. Other cell death effectors are currently being tested for their ability to alter the pathogenesis of BS228.
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1 - University of Chicago, Molecular Genetics and Cell Biology, 1103 E 57th St, EBC, Chicago, IL, 60637, USA
2 - University of Chicago, Molecular genetics and cell biology
3 - University of California - Davis, UC Davis Genome Center
4 - University of California - Davis, UC Davis Genome Center and Department of Plant Sciences
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM