Research Interests
We currently have five ongoing projects, two on important food plants of New York State and fundamental projects on bacterial genetic regulation; metagenomics (environmental genomics) and medicinal properties of honeybee hive glue (propolis). All of our research projects share a common theme in pathogenic bacterial gene regulation. This theme is a mechanism known as quorum sensing (QS) gene regulation and has been widely documented in many pathogenic, symbiotic and commensal host-associated Gram-negative bacteria.
The three key players in QS gene regulation are luxI and luxR homologs and chemical signals, known as N-acyl-homoserine lactones (AHL) or quorum sensing signals, produced by LuxI. LuxR is a signal-dependent regulator that acts as a transcriptional activator or repressor of gene expression. In this system bacteria produce and secrete chemical signals into their surroundings. At a threshold concentration (which measures cell density and environmental porosity), the AHL will bind LuxR. This binding of the quorum-sensing signal (AHL) to its cognate regulatory protein (LuxR homolog) leads to the modulation of global gene expression. QS systems in bacteria have been shown to foster both pathogenic and symbiotic interactions with humans, marine animals and plants.
Our ongoing projects include:
1. Communication signaling in bacteria on grape plants. Many grape plant associated bacteria communicate by small chemical signals called quorum-sensing signals. One project focuses on the characterized of signaling chemicals produced by bacteria isolated from vineyard grape plants.
Chromosome and plasmid-encoded N-acyl homoserine lactones produced by Agrobacterium vitis wildtype and mutants that differ in their interactions with grape and tobacco
Engineering Bacterial Competitiveness and Persistence
in the Phytosphere
2. The application of bacterial signaling molecules, known as quorum sensing signals, in the improvement of corn (maize) against a bacterial pathogen called Pantoea stewartii subsp. stewartii. This bacterial plant pathogen is responsible for Stewart’s wild disease on sweet corn and of leaf blight disease on dent (field) corn. This bacterial pathogen reduces the quantity and quality of sweet corn grown in New York State.
Long- and Short-Chain Plant-Produced Bacterial
N-Acyl-Homoserine Lactones Become Components of
Phyllosphere, Rhizosphere, and Soil
3. Genetic regulation of the stringent response gene rsh and AHL signal generator gene (luxI homolog) in our recently characterized grape tumor-associated Novosphingobium sp. bacterium.
Identification of an rsh Gene from a Novosphingobium sp. Necessary
for Quorum-Sensing Signal Accumulation
4. Metagenomic analysis of a pristine forest soil genetic library for luxI homologs.
5. Effects of honeybee hive glue, also known as propolis, on QS regulation systems in Alpha-proteobacteria.
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