Greg Martin

Boyce Schulze Downey Professor
Greg Martin
gbm7@cornell.edu
Office/Lab: 327/326
Phone: 607-254-1208
Office/Lab: 327/326
Email: gbm7@cornell.edu
Office Phone: 607-254-1208
Lab Phone: 607-220-9610
Graduate Fields: Plant Pathology & Plant-Microbe Biology; Plant Biology
Research Overview

How do bacteria infect plants and how do plants defend themselves from such attacks?

The Martin laboratory studies the molecular basis of bacterial infection processes and the plant immune system. The research focuses on speck disease which is caused by the infection of tomato leaves with the bacterial pathogen Pseudomonas syringae pv. tomato. This is an economically important disease that can decrease both the yield and quality of tomato fruits. It also serves as an excellent system for studying the mechanisms that underlie plant-pathogen interactions and how they have evolved. Many experimental resources including an increasing number of genome sequences are available for both tomato and P. s. pv.tomato. Current work relies on diverse experimental approaches involving methods derived from the fields of biochemistry, bioinformatics, cell biology, forward and reverse genetics, genomics, molecular biology, plant breeding, plant pathology and structural biology.

In the tomato-Pseudomonas interaction, the plant responds rapidly to a potential infection by detecting certain conserved molecules expressed by the pathogen. At this stage the pathogen uses a specialized secretion system to deliver virulence proteins, such as AvrPto and AvrPtoB, into the plant cell. These proteins suppress early host defenses and thereby promote disease susceptibility. Some tomato varieties express a resistance gene, Pto, which encodes a protein that detects the presence of AvrPto or AvrPtoB and activates a second strong immune system that halts the progression of bacterial speck disease.

The Martin lab is currently studying many aspects of the molecular mechanisms that underlie the bacterial infection process and the plant response to infection. One project takes advantage of the genetic natural variation present in wild relatives of tomato to identify new genes that contribute to plant immunity. These genes provide insights into the plant immune system and also can be bred into new tomato varieties to enhance disease resistance. A second project relies on next-generation sequencing methods to identify tomato genes whose expression increases during the interaction with P. s. pv. tomato. The expression of these genes is then reduced by using virus-induced gene silencing or they are mutated using CRISPR/Cas9 to test whether they make a demonstrable contribution to immunity. A third project uses photo-crosslinking and other biochemical methods to characterize plant proteins that play a direct role in recognizing the conserved bacterial molecules that activate the early plant immune system.

The long-term goal in this research is to use the knowledge gained about the molecular basis of plant-pathogen interactions to develop plants with increased natural resistance to diseases. Such plants would require fewer applications of pesticides producing economic and environmental benefits while providing food for consumers with less pesticide residue.

Links

Evolution of immunity

Evolution of pathogen recognition and defense responses in wild species of tomato and tomato heirloom varieties.

Pattern-triggered immunity

The plant immune system 1: Mechanisms underlying recognition and response to microbe-associated molecular patterns.

Effector-triggered immunity

The plant immune system II: Mechanisms underlying recognition and response to pathogen effector proteins.

AvrPto virulence mechanisms

Virtulence mechanisms of the AvrPto effector protein from Pseudomonas syringae pv. tomato.

Methods to study plant immunity

Development of methods and resources to study the plant immune system.

Nicotiana benthamiana genome project

Nicotiana benthamiana genome project.

Intern Projects
Investigating pathogen virulence mechanisms using novel isolates of Pseudomonas syringae pv. tomato collected during a recent outbreak of bacterial speck disease in New York.  Identifying and characterizing immunity-associated genes from wild relatives of tomato.

The Martin laboratory studies the molecular basis of plant immunity and bacterial pathogenesis. Our focus is on the infection of tomato by Pseudomonas syringae pv. tomato as this process results in bacterial speck, an economically important disease, and also serves as a powerful model system for understanding fundamental mechanisms involved in plant-pathogen interactions. On the plant side, we identify and characterize genes, proteins and molecular mechanisms that play a role in host immunity and susceptibility. This work relies on natural variation for these traits that is present in cultivated tomato and in the 12 wild relatives of tomato that occur in South America. On the bacterial side, we study the proteins and associated mechanisms that the pathogen uses to interfere with the plant immune response. For the characterization of both plant and bacterial genes and proteins, we use a variety of experimental approaches including biochemistry, bioinformatics, genetics, genomics, molecular biology, and structural biology.

Examples of research projects for undergraduates in my laboratory include: 1) molecular characterization of novel isolates of Pseudomonas syringae pv. tomato collected during a recent outbreak of bacterial speck disease in New York; and 2) Identifying and characterizing immunity-associated genes from wild relatives of tomato. For more information about the Martin lab, please visit the various sections on this page or the Plant Pathology website.

Click the links to return to the Intern FacultyInternship Program,  Apply for an Internship pages on the BTI website.
Detecting N-myristoylation and S-acylation of host and pathogen proteins in plants using click chemistry.
2016
Author(s):Boyle, P. C., S. Schwizer, S. R. Hind, C. M. Kraus, S. de la Torre Diaz, B. He and G. B. Martin
Plant Methods
12:38
View
iTAK: a program for genome-wide prediction and classification of plant transcription factors, transcriptional regulators, and protein kinases.
2016
Author(s):Zheng, Y., C. Jiao, H. Sun, H. G. Rosli, M. A. Pombo, P. Zhang, M. Banf, X. Dai, G. B. Martin, J. J. Giovannoni, P. X. Zhao, S. Y. Rhee and Z. Fei
Molecular Plant
16,
30223-4
View
High-throughput CRISPR vector construction and generation of tomato hairy roots for the characterization of DNA modifications.
2016
Author(s):Jacobs, T. B. and G. B. Martin
Journal of Visualized Experiments
110,
e53843
View
Nucleic acids encoding proteins with pathogen resistance activity and plants transformed therewith
Greg Martin
Technology Area:Biotic Stress - Disease
US Patent/Application(s): 7,138,569
Publication: EMBO 2003
Nucleic acids encoding proteins with pathogen resistance activity and plants transformed therewith
Greg Martin
Technology Area:Biotic Stress - Disease
US Patent/Application(s): 6,653,533
Publication: EMBO 1997
Flagellin-sensing 3 (‘fls3’) protein and methods of use
Greg Martin
Technology Area:Biotic Stress - Disease
US Patent/Application(s): PCT/US2015/039520
Publication: Science 2016
Gene conferring disease resistance to plants by responding to an avirulence gene in plant pathogens
Greg Martin
Technology Area:Biotic Stress - Disease
US Patent/Application(s): 5,648,599
Publication: Science 1993
Increased Resistance to Race 1 Pseudomonas via Modulation of the Rph1
Greg Martin
Technology Area:Biotic Stress - Disease
US Patent/Application(s): 15/254,370
Bacterial effector proteins which inhibit programmed cell death
Greg Martin
Technology Area:Biotic Stress - Disease
US Patent/Application(s): 7,888,467
Publication: PNAS 2002

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