Our work examines the molecular basis of plant disease resistance. Plant immune systems include many elements that are unique to plants. We study disease resistance in part because host-pathogen dynamics and the molecular workings of immune systems are fascinating biological topics. On a more practical level, one of the best ways to control plant diseases is by genetically determined resistance. Genetic resistance is convenient for growers and minimizes the need for costly, time-consuming and/or potentially toxic external treatments. Plant breeders and their predecessors have selected for improved plant disease resistance since the dawn of agriculture, but the molecular basis of this resistance is only partly understood. We work to identify and study the genes and the biochemical/cellular processes that control pathogen recognition, defense signal transduction, and the execution of successful resistance responses. We seek to expand our basic understanding of plant interacations with pathogens, anticipating that some of this work will contribute to the development of plants with improved disease resistance.

Our research has often utilized Arabidopsis thaliana because of the extraordinary experimental versatility of this plant species. We have often studied responses to the bacterial blight pathogen Pseudomonas syringae pv tomato. Most of our work is now focused on soybean, the most abundant legume crop and a major contributor to world food supplies. In particular, we are discovering mechanisms of soybean resistance to the important soybean pathogen soybean cyst nematode (Heterodera glycines).

Our recent research focuses on three projects:

1) Study and manipulation of soybean cyst nematode disease resistance in soybean.

Soybean cyst nematode is the most economically damaging pathogen of soybean worldwide.  We are uncovering the molecular mechanisms that underpin the function and evolution of soybean Rhg1, a genetic locus that is heavily utilized by farmers to control SCN disease.  We found that three distinct gene products encoded at Rhg1 contribute to SCN resistance.  We also found that a striking form of copy number variation is present at Rhg1 (up to ten tandem repeats of a 31.2kb genome segment encoding those three distinct gene products).  We are studying the mechanisms of Rhg1-mediated resistance, and ways to beneficially manipulate this resistance. We are also studying other genes and processes that contribute to SCN resistance.

2) Poly(ADP-ribosyl)ation, DNA damage and plant-pathogen interactions.

We discovered that poly(ADP-ribosyl)ation plays significant roles in plant responses to infection and have been studying the plant-microbe interaction processes where poly(ADP-ribosyl)ation is relevant, including plant genome stability.  We then discovered that microbial pathogens can activate damage of plant host DNA early in the infection process, and are now curious to know how this damage arises and how plant immune responses mediate protection/preservation of genetic information.

3) Leucine-rich repeat (LRR) protein structure/function/evolution, and plant detection of bacterial flagellin.

We have developed ways to identify and manipulate LRR active sites within plant disease resistance proteins and other LRR proteins. The flagellin receptor FLS2 of Arabidopsis has been our primary model. We have also examined other aspects of receptor activation, and the ways in which some bacterial pathogens have evolved to escape plant detection of their flagellins. Current questions focus on how ligand specificity is determined, and how it can be efficiently altered in a targeted way by in vitro evolution.

• PL Path/Botany 123 Plants, Parasites, And People
• PL Path/Entom/Botany 505 Plant-Microbe Interactions: Molecular and Ecological Aspects
• PL Path 517 Plant Disease Resistance

Butler, K.J., Fliege, C., Zapotocny, R., Diers, B., Hudson, M. and Bent, A.F., 2021. Soybean cyst nematode resistance QTL cqSCN-006 alters the expression of a ɣ-SNAP protein. Mol. Plant-Microbe Interact. https://doi.org/10.1094/MPMI-07-21-0163-R

Bayless, A.M., Zapotocny, R.W., Han, S., Grunwald, D.J., Amundson, K.K., Bent, A.F., 2019. The rhg1-a (Rhg1 low-copy) nematode resistance source harbors a copia-family retrotransposon within the Rhg1-encoded α-SNAP gene. Plant Direct 3:1-19.  https://doi.org/10.1002/pld3.164.

Butler, K.J., Chen, S., Smith, J.M., Wang, X. and Bent, A.F., 2019. Soybean resistance locus Rhg1 confers resistance to multiple cyst nematodes in diverse plant species. Phytopathology, https://doi.org/10.1094/PHYTO-07-19-0225-R

Hu, D., Bent, A.F., Hou, X. and Li, Y., 2019. Agrobacterium-mediated vacuum infiltration and floral dip transformation of rapid-cycling Brassica rapa. BMC Plant Biology 19:246. https://doi.org/10.1186/s12870-019-1843-6

Keppler, B.D., Song, J., Nyman, J., Voigt, C.A., and Bent, A.F., 2018. 3-aminobenzamide blocks MAMP-induced callose deposition independently of its poly(ADPribosyl)ation inhibiting activity. Front. Plant Sci. 9:1907. https://doi.org/10.3389/fpls.2018.01907

Bayless, A.M., Zapotocny, R.W., Grunwald, D.J., Amundson, K.K., Diers, B.W. and Bent, A.F., 2018. An atypical N-ethylmaleimide sensitive factor enables the viability of nematode-resistant Rhg1 soybeans. Proc. Natl. Acad. Sci. (USA) doi:10.1073/pnas.1717070115.  PDF

Briggs A.G., Adams-Phillips L.C., Keppler B.D., Zebell S.G., Arend K.C., Apfelbaum A.A., Smith J.A., and Bent A.F., 2017. A transcriptomics approach uncovers novel roles for poly(ADP-ribosyl)ation in the basal defense response in Arabidopsis thaliana. PLoS ONE 12(12): e0190268. https://doi.org/10.1371/journal.pone.0190268

Bent, A.F. 2017.  Plant Diseases and Strategies for their Control.  Chapter 13 in: Plants, Genes, and Agriculture: Sustainability through Biotechnology, 1st Edition.  M.J. Chrispeels and P. Gepts, Eds.  Sinauer Associates/Oxford University Press. 650 pp. ISBN-13: 978-1605356846

Michelmore, R., et al., 2017. Foundational and Translational Research Opportunities to Improve Plant Health. Mol. Plant-Microbe Interact. 30:515.  PDF

Bayless, A.M., J.M. Smith, J. Song, P.H. McMinn, A. Teillet, B.K. August and A.F. Bent, 2016. Disease resistance through impairment of α-SNAP/NSF interaction and vesicular trafficking by soybean Rhg1. PNAS. doi: 10.1073/pnas.1610150113  PDF

Helft, L., M. Thompson and A.F. Bent, 2016. Directed evolution of FLS2 towards novel flagellin peptide recognition.  PLoS ONE 11(6): e0157155. doi:10.1371/journal.pone.0157155  http://dx.doi.org/10.1371/journal.pone.0157155

Bent, A., 2016. Resistance from Relatives (News and Views).  Nature Biotechnology 34:620-621. doi:10.1038/nbt.3591 PDF

Song, J., B.D. Keppler, R.R. Wise and A.F. Bent, 2015.  PARP2 Is the predominant poly(ADP-ribose) polymerase in Arabidopsis DNA damage and immune responses. PLoS Genet 11(5): e1005200. doi:10.1371/journal.pgen.1005200  PDF

Wang S., Sun Z., Wang H., Liu L., Lu F., Yang J., Zhang M., Zhang S., Guo Z., Bent A.F., Sun W., 2015.  Rice OsFLS2-mediated perception of bacterial flagellins Is evaded by Xanthomonas oryzae pvs. oryzae and oryzicola.  Mol. Plant pii: S1674-2052(15)00099-4. doi: 10.1016/j.molp.2015.01.012.  PDF

Koller, T. and A.F. Bent, 2014.  FLS2-BAK1 extracellular domain interaction sites required for defense signaling activation. PLoS ONE http://dx.plos.org/10.1371/journal.pone.0111185  PDF  Supplemental Materials

Song, J. and A.F. Bent, 2014.  Microbial pathogens trigger host DNA double-strand breaks whose abundance is reduced by plant defense responses.  PLoS Pathogens 10(4):e1004030. doi: 10.1371/journal.ppat.1004030. PDF

Cook, D.E., A.M. Bayless, K. Wang, X. Guo, Q. Song, J. Jiang and A.F. Bent, 2014.  Distinct copy number, coding sequence and locus methylation patterns underlie Rhg1-mediated soybean resistance to soybean cyst nematode. Plant Physiology 165:630-647.   DOI:10.1104/pp.114.235952. PDF

Cao, Y., D.J. Aceti, G. Sabat, J. Song, S. Makino, B.G. Fox and A.F. Bent, 2013.  Mutations in FLS2 Ser-938 Dissect Signaling Activation in FLS2-Mediated Arabidopsis Immunity.  PLoS Pathogens 9(4): e1003313. doi:10.1371/journal.ppat.1003313.   PDF

Cook*, D.E., Lee*, T.G., Guo*, X., Melito, S., Wang, K., Bayless, A., Wang, J., Hughes, T.J., Willis, D.K., Clemente, T., Diers, B.W., Hudson, M.E. and Bent, A.F. (*, co-first authors), 2012.  Copy Number Variation of Multiple Genes at Rhg1 Mediates Nematode Resistance in Soybean.  Science 338:1206-1209.  DOI: 10.1126/science.1228746.  PDF

Sun*, W., Y. Cao*, K.L. Jansen, P. Bittel, T. Boller and A.F. Bent (*co-first authors), 2012. Probing the Arabidopsis flagellin receptor: FLS2-FLS2 association and the contributions of specific domains to signaling function.  Plant Cell 24:1096-1113.   DOI 10.1105/tpc.112.095919.  PDF

Sun, W., L. Liu and A.F. Bent, 2011.   Type III secretion–dependent host defense elicitation and Type III secretion–independent growth within leaves by Xanthomonas campestris pv.campestris.  Mol. Plant Pathol. 12:731-745.   DOI: 10.1111/J.1364-3703.2011.00707.X  PDF

Helft, L., V. Reddy, X. Chen, T. Koller, L. Federici, J. Fernandez-Recio, R. Gupta and A. Bent, 2011. LRR Conservation Mapping to predict functional sites within protein leucine-rich repeat domains. PLoS ONE 6(7): e21614. doi:10.1371/journal.pone.0021614 PDF Supplemental Figures  PDF

Briggs, A.G. and A.F. Bent, 2011. Poly(ADP-ribosyl)ation in plants. Trends Plant Sci. 16:372-372-380. PDF

Danna, C.H., Y.A. Millet, T. Koller, S.-W. Han, A.F. Bent, P.C. Ronald and F.M. Ausubel, 2011. The Arabidopsis flagellin receptor FLS2 mediates the perception of Xanthomonas Ax21 secreted peptides. Proc. Natl. Acad. Sci. (USA) 108:9286-9291. PDF Supplemental Files

Nam, M., S. Koh, S.U. Kim, L.L. Domier, J.H. Jeon, H.G. Kim, S.H. Lee, A.F. Bent and J.S. Moon, 2011.  Arabidopsis TTR1 causes LRR-dependent lethal systemic necrosis, rather than systemic acquired resistance, to Tobacco ringspot virus.  Mol Cells 32:421-429.  DOI:10.1007/s10059-011-0101-z  PDF

Bent, A.F. 2011. Pathogens drop the hint: Don’t forget about phytoalexins. Cell Host & Microbe 9:169-170.

Melito, S., A.L. Heuberger, D. Cook, B.W. Diers, A.E. MacGuidwin and A.F. Bent, 2010. A nematode demographics assay in transgenic roots reveals no significant impacts of the Rhg1 locus LRR-Kinase on soybean cyst nematode resistance. BMC Plant Biology 10:104.   PDF  PubMed

Kim, M., D.L. Hyten, A.F. Bent and B.W. Diers, 2010. Fine mapping of the SCN resistance locus rhg1-b from PI 88788. Plant Genome 3:81-89.  PDF

Adams-Phillips, L., A.G. Briggs and A.F. Bent, 2010.  Disruption of poly(ADP-ribosyl)ation mechanisms alters responses of Arabidopsis thaliana to biotic stress.  Plant Physiol. 152:267-280.  PDF  PubMed

Allen, C., A. Bent and A. Charkowski, 2009. Underexplored niches in research on plant pathogenic bacteria. Plant Physiol. 150:1631-1637.  PDF

Adams-Phillips. L., J. Wan, X. Tan, F.M. Dunning, B.C. Meyers, R.W. Michelmore and A.F. Bent, 2008. Discovery of ADP-ribosylation and other plant defense pathway elements through expression profiling of four different Arabidopsis-Pseudomonas R/avr interactions.  Mol. Plant-Microbe Interact. 21:646-657.  PDF  PubMed

Genger, R.K., G.I. Jurkowski, J.M. McDowell, H. Lu, H.W. Jung, J.T. Greenberg and A.F. Bent, 2008. Signaling pathways that regulate the enhanced disease resistance of Arabidopsis “defense, no death” mutants. Mol. Plant-Microbe Interact. 21:1285-1296.  PDF  PubMed

Dunning, F.M., W. Sun, K.L. Jansen, L. Helft and A.F. Bent, 2007. Identification and mutational analysis of Arabidopsis FLS2 Leucine-Rich Repeat domain residues that contribute to flagellin perception. Plant Cell. 19:3297-3313. PDF PubMed

Bent, A. and D. Mackey, 2007. Elicitors, Effectors and R Genes: The new paradigm and a lifetime supply of questions. Annu. Rev. Phytopathol. 45:399-436. PDF PubMed

Tan, X., B.C Meyers, A. Kozik, M.A.L. West, M. Morgante, D.A. St. Clair, A.F. Bent and R.W. Michelmore, 2007. Global expression analysis of nucleotide binding site-leucine rich repeat-encoding and related genes in Arabidopsis. BMC Plant Biology 7:5.

Suarez-Rodriguez MC, Adams-Phillips L, Liu Y, Wang H, Su SH, Jester PJ, Zhang S, Bent AF, Krysan PJ, 2006. MEKK1 Is Required for flg22-induced MPK4 Activation in Arabidopsis Plants. Plant Physiol. 143:661-669. PDF PubMed

Sun, W., F.M. Dunning, C. Pfund, R. Weingarten and A.F. Bent, 2006. Within-species flagellin polymorphism in Xanthomonas campestris pv. campestris and its impact on elicitation of Arabidopsis FLS2-dependent defenses. Plant Cell 18:764-779. PDF PubMed

Bent, A.F., T.K. Hoffman, J.S. Schmidt, G.L. Hartman, D.D. Hoffman, X. Ping, M.L. Tucker, 2006. Disease- and Performance-Related Traits of Ethylene-Insensitive Soybean. Crop Science 43:893-901. PDF

Bent, A.F., 2006.Arabidopsis thaliana Floral Dip Transformation Method. In: Agrobacterium Protocols – 2 nd Edition (K. Wang, Ed.). Methods in Molecular Biology Book Series, Humana Press, Totowa, NJ. Methods in Molecular Biology 343:87-103. PubMed

Quirino, B.F., R. Genger, J.H. Ham, G. Zabala and A.F. Bent, 2004. Identification and functional analysis of Arabidopsis proteins that interact with resistance gene product RPS2 in yeast. Physiol. Molec. Plant Pathol. 65:257-267. PDF Abstract

Jurkowski, G. I., R.K. Smith, I.-c. Yu, J.H. Ham, S.B. Sharma, D.F. Klessig, K.A. Fengler and A.F. Bent, 2004. ArabidopsisDND2, a second cyclic nucleotide-gated ion channel gene for which mutation causes the “defense, no death” phenotype. Mol. Plant-Microbe Interact. 17:511-520. PDF PubMed

Pfund, C., J. Tans-Kersten, J., F.M. Dunning, J.M. Alonso, J.R. Ecker, C. Allen and A.F. Bent, 2004. Flagellin is not a major defense elicitor inRalstonia solanacearum cells or extracts applied toArabidopsis thaliana. Mol. Plant-Microbe Interact. 17:696-706. PDF PubMed

Chan, C., R. K. Smith, A. F. Bent and M. Sussman, 2003 A cyclic nucleotide-gated ion channel,CNGC2, is crucial for plant development and adaptation to calcium stress. Plant Physiology 132:728-731. PDF PubMed

Quirino, B. F. and A. F. Bent (2003) Deciphering host resistance and pathogen virulence: The Arabidopsis/Pseudomonas interaction as a model. Mol. Plant Pathol. 4:517-530. PDF Abstract

Wan, J., F.M. Dunning and A. F. Bent, 2002. Probing plant-pathogen interactions and downstream defense signaling using DNA microarrays. Funct. & Integr. Genomics 2: 259-273. PDF PubMed

Bent, A. F., 2002. “Crop Diseases and Strategies for their Control.” Chapter 15 In: Plants, Genes and Agriculture, 2nd Ed. M. Chrispeels and D. Sadava, Eds., Jones and Bartelett, Inc., Sudbury, MA, pp. 390-413.

Bent. A. F., 2002. “Reconnecting Farms and Ecosystems, If It Pays.” Review of the book:The Farm as Natural Habitat: Reconnecting Farm Systems with Ecosystems (D. L. Jackson and L. L. Jackson, eds., Island Press, Washington D.C., 2002). Science 298:1340-1341. PDF

Bent, A. F., 2001. Plant mitogen-activated protein kinase cascades: Negative regulatory roles turn out positive (Commentary). Proc. Natl. Acad. Sci. (USA) 98:784-786. PDF PubMed

M.S. Bachman, J.P. Tamulonis, C.D. Nickell, and A.F. Bent. 2001. Molecular markers linked to brown stem rot resistance genes, Rbs1 and Rbs2, in soybean. Crop Sci. 41:527-535. PDF

Banerjee, D., Z. Zhang, and A.F. Bent (2001). The LRR domain can determine effective interaction between RPS2 and other host factors in Arabidopsis RPS2-mediated disease resistance. Genetics 158:439-450. PDF PubMed

Bent, A. F., 2000.  Arabidopsisin planta transformation: Uses, mechanisms, and prospects for transformation of other species [invited Update for special issue on Arabidopsis].  Plant Physiol. 124:1540-1547. PubMed

Clough, S. J., K. A. Fengler, B. Lippok, R. K. Smith Jr., I.-c. Yu, and A. F. Bent, 2000. The Arabidopsis dnd1 “defense, no death” gene encodes a mutated cyclic nucleotide-gated ion channel. Proc. Natl. Acad. Sci (USA) 97:9323-9328. PubMed

Desfeux, C., S. J Clough and A. F. Bent, 2000. Female reproductive tissues are the primary target of Agrobacterium-mediated transformation by the Arabidopsis floral-dip method. Plant Physiol. 123:895-904 PubMed

Yu, I.-c., K. A. Fengler, S. J. Clough and A. F. Bent, 2000. Identification of Arabidopsis mutants exhibiting an altered hypersensitive response in gene-for-gene disease resistance. Mol. Plant-Microbe Interact. 13:277-286. PubMed

Hoffman, T., J. S. Schmidt, X. Zhang and A. F. Bent, 1999. Isolation of ethylene-insensitive soybean mutants that are altered in pathogen susceptibility and gene-for-gene disease resistance. Plant Physiology 119:935-950. PubMed

Schmidt, J. S., J. E. Harper, T. K. Hoffman, and A. F. Bent, 1999. Regulation of soybean nodulation independent of ethylene signaling. Plant Physiology 119:951-960. PubMed

Yu, I.-c., J. Parker and A. F. Bent, 1998. Gene-for-gene disease resistance without the hypersensitive response in Arabidopsis dnd1 mutant. Proc. Natl. Acad. Sci. USA 95:7819-7824. PubMed

Clough, S. J. and A. F. Bent, 1998. Floral dip: a simplified method for Agrobacterium -mediated transformation of Arabidopsis thaliana. Plant J. 16:735-743. PubMed

Lee, J.-M., G. L. Hartman, L. L. Domier, and A. F. Bent, 1996. Identification and map location of TTR1, a single locus in Arabidopsis thaliana that confers tolerance to tobacco ringspot nepovirus. Mol. Plant-Microbe Interact. 9:729-735. PubMed

Bent, A. F., B. N. Kunkel, D. Dahlbeck, K. L. Brown, R. Schmidt, J. Giraudat, J. Leung, and B. J. Staskawicz, 1994. RPS2 of Arabidopsis thaliana: A leucine-rich repeat class of plant disease resistance genes. Science 265:1856-1860. PubMed

Bent, A. F., and I.-c. Yu, 1999. Applications of Molecular Biology to Plant Disease and Insect Resistance. Advances in Agronomy 66:251-298.

Bent, A. F., 1996. Plant disease resistance genes: Function meets structure. Plant Cell 8:1757-1771. PDF