Keywords

  • bacterial genomics
  • bacterial protein secretion
  • microbial pathogenesis
  • plant disease
  • plant-microbe biology
  • plant-microbe interactions

Collmer, Alan Raymond

Professor
Our goal is to understand the molecular mechanisms that enable bacteria to attack plants. Much of our current work is focused on Pseudomonas syringae pv. tomato DC3000, which is a pathogen of tomato and the model plant Arabidopsis thaliana. For comparative purposes, we are also studying P. syringae pv. phaseolicola 1448A, which causes halo blight of bean. Like many host-specific plant pathogens, P. syringae is a "stealth" parasite that can multiply for several days in host tissues before symptoms, such as necrotic spots, develop. We have learned that the ability of P. syringae to multiply in the intercellular spaces of plant leaves and cause disease is dependent on a "type III" secretion system that injects virulence effector proteins into host cells. Variants of this injector system are also used by many important animal pathogens (for example, Yersinia pestis, the plague pathogen) to deliver their virulence proteins. How many effector proteins are injected by P. syringae, what do they do inside plant cells to subvert host metabolism, and what other adaptations does this sophisticated parasite have for life in plants? To answer these questions, we and a team of researchers from the USDA/ARS Plant-Microbe Interaction research group at Cornell and the Boyce Thompson Institute for Plant Research have been characterizing the genome sequences of these two P. syringae strains and developing a variety of bioinformatic, biochemical, genetic, and cell biological tools to support a genome-wide study of virulence mechanisms and to foster functional genomic investigations by the worldwide research community.

research

research and scholarship focus

The focus of our research is on the functional genomics of virulence in the plant pathogenic bacterium Pseudomonas syringae.

research areas

affiliations

faculty appointment in

member of graduate field

other Cornell affiliations

teaching

teaching focus

PlPa 601 Concepts of Plant Pathology|Spring semester 3 credits |The course is intended to be a core course for graduate students with a major or minor in the Field of Plant Pathology and Plant-Microbe Biology. The course concerns concepts in host-pathogen relationships with an emphasis on the roles of molecules and cell structures in determining the outcome of an interaction. Evidence for the role of putative disease determinants is explored in the context of universal stages of pathogenesis and representative pathosystems. Discussion periods provide time for analysis of special topics, critiquing of research papers, comparisons of pathosystems, evaluation of grant proposals, and review sessions. Students develop a personal computer-based reference collection for use in several aspects of the course. Students also write a grant proposal and review each others proposals in mock panels. The final discussion session of the semester is used for the Big Picture Game, in which student teams compete in the development of a comprehensive picture of plant-pathogen interactions. The final exam includes both written and oral components.

teaches

service

outreach focus

The major outreach activity of the Pseudomonas-Plant Interaction (PPI) project is "High School Connect." This is a series of interlinked lab modules, which are integrated with an interactive website that is part of the PPI website (http://pseudomonas-syringae.org) and designed to meet the requirements for the Living Environment Curriculum and State Standards in Science and Math Education for New York State Regents and AP biology high school students. The High School Connect lab modules use P. syringae-plant interactions to engage students in investigative activities that begin with host responses (module 1: inoculate leaves with P. syringae and observe HR), progress to microbial processes (module 2: bacterial conjugation of a marker gene) and molecular biology (module 3: PCR to detect a bacterial virulence gene), and culminate with genomics and bioinformatics (module 4: find related virulence genes, resistance genes and explore the human genome using GenBank). The experiments and website connect biology with social sciences, students with active research frontiers, and high school students with graduate students and their career choices through Quicktime videos and other web resources. The modules are distributed through the CIBT Lending Library. PPI project personnel, including graduate students, participate in facilitating the use of the modules through presentations at weekend and summer CIBT events for teachers and by visiting high school classrooms. The High School Connect project has also enabled graduate students to get teaching experience with high school students and high school teachers to gain further research experience.

current professional activities

  • Chair, Bacteriology Committee, American Phytopathological Society, 1992-93 
  • Board Member, International Society for Molecular Plant Microbe Interactions, 1994-present 
  • Co-editor, Plant Cell, 1995-2000 
  • Editorial Board Member, Journal of Bacteriology, 1997-present
  • Editorial Board Member, Annual Review of Phytopathology, 1997-2002

background

educational background

  • Ph. D., Cornell University, 1981
  • B.A., Antioch College, 1973

awards and distinctions

  • Noel T. Keen Award for Excellence in Molecular Plant Pathology, American Phytopathological Society, 2003.
  • Fellow of the American Academy of Microbiology, 2000
  • Fellow of the American Phytopathological Society, 1996

featured in

publications

speaker at Cornell event

Keywords: bacterial genomics, bacterial protein secretion, microbial pathogenesis, plant disease, plant-microbe biology, plant-microbe interactions