Research Groups
Bacteriology and Plant Bacteriology
Research Interests and Description
Research Interests
Bacterial inter-cellular communication (quorum sensing) in rice associated bacteria
Description of Research
It is now recognized that bacteria behave/synchronize as a community employing a level of gene regulation involving intercellular communication (quorum sensing, QS) organized by the production and detection of small signal molecules. QS has been studied in many bacterial species and shown to provide a significant advantage to a community of bacteria by adapting to environmental conditions and often enhancing its defense capabilities against other microorganisms or eukaryotic resistance mechanisms.In Gram-negative bacteria, N-acyl homoserine lactones (AHLs) are to date the most commonly used signal molecules being produced by a synthase enzyme belonging to the LuxI protein family; a transcriptional regulator, belonging to the LuxR family, then forms a complex with the cognate AHL at threshold levels altering the transcriptional activity of target genes.
Research interests focus on AHL QS in important Gram-negative bacteria associated rice; more precisely with (i) rice-rhizosphere beneficial Pseudomonas spp., (ii) in beneficial rice endophytic Burkholderia spp., and (ii) in rice pathogenic Xanthomonas oryzae, Burkholderia glumae and Pseudomonas fuscovaginae. How these bacteria employ similar QS mechanisms to either establish a beneficial association with the plant in the rhizosphere or to colonize and cause disease is currently being studied. The overall picture of AHL QS of rice-associated bacteria is beginning to emerge. Rice pathogenic B. glumae possesses an AHL QS system which is very important for grain rot (panicle blight) as it coordinates the regulation of the phyototoxin toxoflavin as well as the secreted lipase which is a virulence factor. B. plantarii and P. fuscovaginae also possess an AHL QS system involved in virulence and we are currently identifying target loci. Rice endophytic Burkholderia belonging to several recently classified species contain a very well conserved AHL QS system; we are currently studying its role in planta. Rice rhizosphere beneficial Pseudomonas on the other hand, most often do not employ AHL QS for inter-cellular communication and when they do its role is unpredictable. Our studies in Xanthomonas oryzae have established that a LuxR-family protein is interacting with a rice compound and then regulates virulence associated factors. Our studies in all these systems actively continues and we are also evaluating possible interplay between beneficial and pathogenic bacteria which could lead to the design of possible biocontrol and biofertilizer strategies.
Recent Publications
Ferluga, S., Venturi, V. 2009. OryR is a LuxR-family protein involved in interkingdom signaling between pathogenic Xanthomonas oryzae pv. oryzae and rice. J Bacteriol 191, 890-897 [Pubmed link]
Netotea, S., Bertani, I., Steindler, L., Kerenyi, A., Venturi, V. Pongor, S. 2009. A simple model for the early events of quorum sensing in Pseudomonas aeruginosa: modeling bacterial swarming as the movement of an "activation zone". Biol Direct 4, 6
Steindler, L., Bertani, I., De Sordi, L., Schwager, S., Eberl, L. Venturi, V. 2009. LasI/R and RhlI/R quorum sensing in a strain of Pseudomonas aeruginosa beneficial to plants. Appl Environ Microbiol 75, 5131-5140 [Pubmed link]
Subramoni, S., Venturi, V. 2009. LuxR-family 'solos': bachelor sensors/regulators of signalling molecules. Microbiology 155, 1377-1385 [Pubmed link]
Subramoni, S.,
Venturi, V. 2009. PpoR is a conserved unpaired LuxR solo of Pseudomonas
putida which binds N-acyl
homoserine lactones. BMC Microbiol 9, 125 [Pubmed link]
Steindler, L., Bertani, I., De Sordi, L., Bigirimana, J. Venturi, V. 2008. The presence, type and role of N-acyl homoserine lactone quorum sensing in fluorescent Pseudomonas originally isolated from rice rhizospheres are unpredictable. FEMS Microbiol Lett 288, 102-111 [Pubmed link]
