Eric W. Triplett

Professor and Chair

Department of Microbiology and Cell Science University of Florida 

B.S. (1976) Rutgers University, Cook College, New Brunswick, NJ
M.S. (1978) University of Maryland, College Park
Ph.D. (1981)  University of Missouri, Columbia
Postdoctoral (1981-1982) University of Wisconsin-Madison       Ph.D. (1981)  University of Missouri, Columbia

Description of Research

Colonization of plants by endophytic bacteria.

Endophytic bacteria are defined as those bacteria that enter plants without causing disease or any organized symbiotic structures.  There are three important reasons to study bacterial endophytes.  First, these bacteria often enhance plant growth under field and greenhouse conditions.  Second, these strain can fix nitrogen and we hope to find ways to improve the nitrogen nutrition with such strains.  And third, some human pathogenic bacteria can colonize the interior of plants. 

We have learned that strains within the same bacterial species can differ radically in the their ability to enter plant hosts.  We are seeking to understand the basis of this strain-specificity.  We also know that an endophyte can have a broad-host-range and colonize monocots as well as dicots.  For most of this work, we use a model endophytic bacterium called Klebsiella pneumoniae 342, also referred to as Kp342.  A single cell of Kp342 in the inoculum is sufficient to fully colonize several plant hosts.  This strain fixes nitrogen and can enhance the growth of a number of plant hosts.

Microbial diversity and ecology.

I work with several colleagues at the University of Wisconsin-Madison on an NSF-supported Microbial Observatory of the North Temperate Lakes Long Term Ecological Research site (http://microbes.limnology.wisc.edu).  We have observed tremendous variation in microbial diversity in lakes across time and space.  Different lakes vary greatly in microbial diversity but within lake variability across time is also very significant.  In one of our lakes, changes in microbial diversity appears to be correlated with biological changes that occur in the lake over time rather than changes in water chemistry.  We have developed two new tools for microbial diversity research.  These are Automated Ribosomal Intergenic Spacer Analysis (ARISA) and a web-based tool for T-RFLP analysis. 

Currently we are characterizing the taxa found in our study lakes and plan to culture those bacteria that are either unusual or are important in productivity.

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Selected Publications

Pongslip, N., E.W. Triplett, and M.J. Sadowsky.  2005. Detection of homoserine lactone-like quorum sensing molecules in Bradyrhizobium strains.  Current Microbiol. 51:250-254.

Iniguez, A.L., Y. Dong., H.D. Carter, B.M.M. Ahmer, J.M. Stone, and E.W. Triplett.  2005. Regulation of enteric endophytic bacterial colonization by plant defenses.  Molecular Plant-Microbe Interactions 18:169-178.

Yannarell, A.C. and E.W. Triplett.  2005.  Geographic and environmental sources of variation in lake bacterial community composition.  Appl. Environ. Microbiol. 71:227-239.

Iniguez, A.L., Y. Dong, and E.W. Triplett.  2004.   Nitrogen fixation in wheat provided by Klebsiella pneumoniae 342.  Molec. Plant-Microbe Interact. 17:1078-1085.

Graham, J.M., A.D. Kent, G.H. Lauster, A.C. Yannarell, L.E. Graham, T.K. Kratz, and E.W. Triplett.  2004.  Seasonal dynamics of phytoplankton and protoplankton communities in a northern temperate humic lake: diversity in a dinoflagellate dominated system. Microbial Ecology (in press).

Kent, A.D, S.E. Jones, A.C. Yannarell, J.M. Graham, G.H. Lauster, T.K. Kratz, and E.W. Triplett.  2004.  Annual patterns in bacterioplankton community variability in humic lake. Microbial Ecology (in press). 

Iniguez, A.L., E.A. Robleto, A.D. Kent, and E.W. Triplett.  2004.  Significant yield increase in Phaseolus vulgaris obtained by inoculation with a trifolitoxin-producing, Hup+ strain of Rhizobium leguminosarum bv. phaseoli.  Crop Management (on line only: http://www.plantmanagementnetwork.org/pub/cm/

/pub/cm/review/2004/yield/, 5 pages). 

Yannarell, A.C. and E.W. Triplett. 2004. Within- and between-lake variability in the composition of bacterioplankton communities: investigations at multiple spatial scales.  Appl. Environ. Microbiol. 70:214-223.

Yannarell, A.C., A.D. Kent, G.H. Lauster, T.K. Kratz, and E.W. Triplett.  2003.  Temporal patterns in bacterial communities in three temperate lakes of different trophic status. Microbial Ecology 46:391-405.

Kent, A.D., D.J. Smith, B.J. Benson, and E.W. Triplett.  2003.  Web-based phylogenetic assignment tool for analysis of terminal restriction fragment length polymorphism profiles of microbial communities.  Appl. Environ. Microbiol. 69:6768-6776.

Dong, Y., A.L. Iniguez, and E.W. Triplett.  2003.  Quantitative assessments of the host range and strain specificity of endophytic colonization by Klebsiella pneumoniae 342. Plant and Soil 257:49-59.

Dong, Y., M.K. Chelius, S. Brisse, N. Kozyrovska, G. Kovtunovych, R. Podschun, and E.W. Triplett.  2003.  Comparisons between two Klebsiella: the plant endophyte K. pneumoniae 342 and a clinical isolate, K. pneumoniae MGH78578.  Symbiosis 35:247-259. 

Dong, Y., A.L. Iniguez, B.M.M. Ahmer, and E.W. Triplett.  2003. Kinetics and strain specificity of rhizosphere and endophytic colonization by enteric bacteria on seedlings of Medicago sativa and Medicago trucatula.  Appl. Environ. Microbiol. 69:1783-1790.

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Chelius, M.K., J.A. Henn, and E.W. Triplett.  2002.  Runella zeae sp. nov., a novel Gram-negative bacterium from the stems of surface-sterilized Zea mays. Inter. J. System. Evol. Microbiol. 52:2303-2308.  

Leong, S.A., C. Allen, and E.W. Triplett, eds.  2002.  Biology of Plant-Microbe Interactions, Vol. 3, International Society for Plant-Microbe Interactions, St. Paul, MN, 360 pp. 

Scupham, A.J., Y. Dong, and E.W. Triplett.  2002. Role of tfxE, but not tfxG, in trifolitoxin resistance.  Appl. Environ. Microbiol. 68:4334-4340.

Kent, A.D. and E.W. Triplett.  2002.  Microbial communities and their interactions in soil and rhizosphere ecosystems. Annu. Rev. Microbiol. 56:211-236.

Herlache, T.C. and E.W. Triplett.  2002.  Extending the host range of the biological control phenotype expressed by avirulent Agrobacterium vitis F2/5 by addition of the trifolitoxin production and resistance genes. BMC Biotechnology 2:2. 

Riggs, P.J., R.L. Moritz, M.K. Chelius, Y. Dong, A.L. Iniguez, S.M. Kaeppler, M.D. Casler, E.W. Triplett.  2002.  Isolation and characterization of diazotrophic endophytes from grasses and their effects on plant growth.  In: Nitrogen Fixation: Global  Perspectives, Proceedings of the 13th International Congress on Nitrogen Fixation, T.R. Finan, M.R. O’Brian, D.B. Layzell, J.K. Vessey, W.E. Newton, eds. pp. 263-267. 

Riggs, P.J., M.K. Chelius, A.L. Iniguez, S.M. Kaeppler, and E.W. Triplett.  2001.  Enhanced maize productivity by inoculation with diazotrophic bacteria.  Austr. J. Plant Physiol. 28:829-836.

Yanni, Y.G., R.Y. Rizk, F.K. Abd El-Fattah, A. Squartini, V. Corich, A. Giacomini, F. de Bruijn, J. Rademaker, J. Maya-Flores, P. Ostrom, M. Vega-Hernandez, R.I. Hollingsworth, E. Martinez-Molina, P. Mateos, E. Velazquez, J. Wopereis, E. Triplett, M. Umali-Garcia, J.A. Anarna, B.G. Rolfe, J.K. Ladha, J. Hill, R. Mujoo, P.K. Ng, and F.B. Dazzo.  2001.  The beneficial plant growth-promoting association of Rhizobium leguminosarum bv. trifolii with rice roots.  Austr. J. Plant Physiol. 28:845-870.

Dong, Y., J.D. Glasner, F.R. Blattner, and E.W. Triplett.  2001.  Genomic interspecies microarray hybridization: rapid discovery of three thousand genes in the maize endophyte, Klebsiella pneumoniae 342, by microarray hybridization with Escherichia coli K12 open reading frames.  Appl. Environ. Microbiol. 67:1911-1921.

Chelius, M.K. and E.W. Triplett.  2001.  The diversity of Archaea and Bacteria in the roots of Zea mays L.  Microbial Ecology 41:252-263.

Fisher, M.M., J.L. Klug, G. Lauster, M. Newton, and E.W. Triplett.  2000.  Effects of resources and trophic interactions on freshwater bacterioplankton.  Microbial Ecology 40:125-138.

Chelius, M.K. and E.W. Triplett.  2000.  Dyadobacter fermentans gen. nov., sp. nov., a novel gram-negative bacterium isolated from surface-sterilized Zea mays stems.  Inter. J. System. Evol. Microbiol. 50:351-358.

Chelius, M.K. and E.W. Triplett.  2000.  Diazotrophic endophytes assoicated with maize.  In: Prokaryotic Nitrogen Fixation: a Model System for the Analysis of a Biological Process, E.W. Triplett, ed., Horizon Scientific Press, Norfolk, UK, pp. 779-792.

Scupham, A.J., E.A. Robleto, and E.W. Triplett.  2000.  Solving the competition problem: genetic and field approaches to enhance the effectiveness of the Rhizobium-legume symbiosis.  In: Prokaryotic Nitrogen Fixation: a Model System for the Analysis of a Biological Process, E.W. Triplett, ed., Horizon Scientific Press, Norfolk, UK, pp. 251-278.

Triplett, E.W. (Ed.). 2000.  Nitrogen fixation: a model system for the analysis of a biological process.  (A compilation of 44 chapters written by experts from around the world.)  Horizon Scientific Press, Norfolk, UK, 800 pp. 

Chelius, M.K. and E.W. Triplett.  2000.  Immunolocalization of dinitrogenase reductase produced by Klebsiella pneumoniae in association with Zea mays L.  Appl. Environ. Microbiol. 66:783-787.

Dazzo, F.B., Y. G. Yanni, R. Rizk, F. de Bruijn, J. Rademaker, A. Squartini, V. Corich, P. Mateos, E. Martinez-Molina, E. Velazquez, J. Biswas, R. Hernandez,  J. K. Ladha, J. Hill, J. Weinman, B. Rolfe, M. Vega-Hernandez, J. J. Bradford, R. I. Hollingsworth, P. Ostrom, E. Marshall, T. Jain, G. Orgambide, S. Philip-Hollingsworth, E. Triplett, K. Malik, J. Maya-Flores, M. Umali-Garcia, and M. L. Izaguirre-Mayoral. 2000. Progress in multi-national collaborative studies on the beneficial association between Rhizobium leguminosarumrice. In J.K. Ladha and P. M. Reddy (eds.), The Quest for Nitrogen Fixation in Rice. International Rice Research Institute, Manila, The Philippines, pp. 167-189.

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