Dhirendra Kumar, Ph.D.
Assistant Professor
Department of Biological Sciences, Box 70703, East Tennessee State University, Johnson city, TN 37614-1710
Phone: (423) 439-6928, Fax: (423) 439-5958, email : kumard@etsu.edu
RESEARCH
My lab is interested in studying the salicylic acid mediated defense signaling in plants. Salicylic acid (SA) mediated pathway is one of the major pathways by which plants defend themselves. Plants resisting pathogen attack produce high amounts of salicylic acid which leads to activation of defense pathways. How the SA activates defense signaling pathways? is unclear. Using biochemical approach we identified a 29 kDa protein, salicylic acid binding protein 2 (SABP2) which binds SA with high affinity (KD=~90 nM). SABP2 is a esterase which converts the inactive methyl salicylate to the active salicylic acid. High amounts of methyl salicylate is produced in the plants resisting pathogen attack. Three dimensional structure analysis of SABP2 in complex with SA shows that SA binds in the active site of the SABP2. This binding inhibits the enzymatic activity of SABP2 which stops the conversion of MeSA to SA. Plants continue to make MeSA which is not only travels to other parts of the plant but also to neighboring plants. SABP2 in the healthy parts of the plant catalyzes the conversion of MeSA into SA which turns on the defense pathway and plant exhibits systemic acquired resistance (SAR). RNAi-mediated silencing of SABP2 in tobacco rendered the plant more susceptible to pathogen attack and it lost its ability to mount the systemic acquired resistance (SAR) response. These RNAi plants were also compromised in expression of defense genes. Our recent studies suggest that methyl salicylate is the long sought mobile signal for plant innate immunity which the scientists have been searching for more that five decades (http://www.sciencemag.org/cgi/content/summary/sci;318/5847/31a).
Publications
Vlot, Corina., Liu, Po-Pu, Cameron, R.K., Park, S.W., Yang,Y., Kumar, D., Zhou, F., Paddukavidana, T., Gustafsson, C., Pichersky, E. and Klessig, D.F. (2008) Identification of likely orthologs of tobacco salicylic acid-binding protein 2 and their role in systemic acquired resistance in Arabidopsis thaliana. The Plant Journal (accepted for publication).
Kumar, D. and Klessig, D.F. (2008) The search for the salicylic acid receptor led to discovery of the SAR signal receptor. To be published in Sept, 2008 issue of Plant Signaling & Behavior. http://www.landesbioscience.com/journals/psb/article/5844
Park, S.-W., Kaimoyo, E., Kumar, D., Mosher, S., and Klessig, D. F. (2007) Methyl Salicylate is a Critical Mobile Signal for Plant Systemic Acquired Resistance. Science vol 318 no. 5: 113-116. http://www.sciencemag.org/cgi/content/abstract/318/5847/113
Salicylic acid binding protein (SABP)2 and Systemic Acquired Resistance (2007). In “Biology of Plant Microbe Interactions”, edited by F. Sánchez, C. Quinto I.M. López-Lara and O. Geiger, IS-MPMI, St Paul, MN. 5:176-181.
Kumar D., Gustafsson C. and Klessig, D.F. (2006) Validation of RNAi silencing specificity using synthetic genes: Salicylic acid binding protein 2 is required for innate immunity in plants. The Plant Journal 45: 863-868 http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1365-313X.2005.02645.x
Menke FL, Kang H.G., Chen Z., Park, J.M., Kumar, D. and Klessig, D.F. (2005) Tobacco transcription factor WRKY1 is phosphorylated by the MAP kinase SIPK and mediates HR like cell death in tobacco. Mol. Plant-Microbe Interact. 18: 1027-34. http://www.apsnet.org/mpmi/pdfs/2005/MPMI-18-1027.pdf
Farhad, F., Yang*, Y., Kumar*, D., Chen, Y., Fridman, E., Park, S.W., Chiang, Y., Acton, T.B., Montelione, G.T., Pichersky, E., Klessig D.F. and Tong, L. (2005) Structural and biochemical studies identify tobacco SABP2 as a methyl salicylate esterase and implicate it in plant innate immunity. Proc. Natl. Acad. Sci. USA. 102: 1773-1778 *contributed equally to this work. http://www.pnas.org/cgi/reprint/102/5/1773.pdf
Kumar, D. and Klessig, D.F. (2003) The high-affinity salicylic acid-binding protein 2 is required for plant innate immunity and has salicylic acid-stimulated lipase activity. Proc. Natl. Acad. Sci. USA. 100: 16101-16106. http://www.pnas.org/cgi/reprint/100/26/16101.pdf
SA- and NO-mediated signaling in Plant Disease Resistance (2002) In: Biology of Plant-Microbe Interactions. Ed. S.A. Leong, C. Allen, and E.W. Triplet, IS-MPMI, St Paul, MN. Vol. 3, pp 78-82.
Kumar, D. and Klessig, D.F. (2000) Differential induction of tobacco MAP kinases by the defense signals nitric oxide, salicylic acid, ethylene and jasmonic acid. Mol. Plant-Microbe Interact. 13: 347-351. http://www.apsnet.org/mpmi/pdfs/2000/0112-01N.pdf
Klessig, D.F., Durner, J., Zhou, J.M., Kumar, D., Navarre, R., Zhang, S., Shah, J., Wendehenne, D., Du, H., Trifa, Y., Noad, R., Kachroo, P., Pontier, D., Lam, E. and Silva, H. (2000) NO and salicylic acid signaling in plant defense. Proc. Natl. Acad. Sci. USA. 97: 8849-8855. http://www.pnas.org/cgi/reprint/97/16/8849.pdf
Salicylic acid- and nitric oxide-mediated signal transduction in plant disease resistance (2000) In: Biology of Plant-Microbe Interactions 2: 13-18. Edited by P. de Witt., T. Bisseling and W. Stiekema. Kluwer Academic Publishers, The Netherlands.
Salicylic acid- and nitric oxide-mediated signaling in plant-microorganism interactions (2000) In: 2000 Years of Natural Products Research; Past, Present and Future. Edited by T.J.C. Luijendijk, Phytoconsult, Leiden, The Netherlands, pp. 105-118.
Salicylic acid- and nitric oxide-mediated signal transduction in disease resistance (2000). In: Signal Transduction in Plants: Current Advances. Edited by S.K. Sopory, R. Oelmüller and S.C. Maheshwari. Kluwer Academic/ Plenum Publishers, The Netherlands. pp. 201-207.
Gaikwad, A., Tewari, K.K., Kumar, D., Chen, W. and Mukherjee, S.K. (1999) Isolation and characterization of the cDNA encoding a glycosylated accessory protein of pea chloroplast DNA polymerase. Nuc. Acids Res. 27: 3120-3129. http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=148538&blobtype=pdf
Kumar, D., Verma, H.N., Tuteja, N. and Tewari, K.K. (1997) Cloning and characterization of a gene encoding an antiviral protein from Clerodendrum aculeatum L. Plant. Mol. Biol. 33: 745 751 http://www.springerlink.com/content/h6g550345567h7m3/fulltext.pdf
Verma, H.N, Srivastava, S., Varsha and Kumar, D. (1996) Induction of systemic resistance in plants against viruses by a basic protein from Clerodendrum aculeatum leaves. Phytopathology 86: 485-91 http://www.apsnet.org/phyto/PDFS/1996/Phyto86n05_485.pdf
Patents
Klessig, D.F. and Kumar, D. Novel Salicylic Acid-Binding Protein Encoding Nucleic acid, SABP2, and Methods of Use Thereof, Patent No. US 7169966.
Klessig, D.F. and Kumar, D. Methods of determining specificity of RNAi silencing. US Patent Application No. 11/452,821.
TEACHING
BIOL 5100 Topics: Cell and Molecular Biology
BIOL 4300-008 Seminar in Biological Sciences
BIOL 4147/5147 Biochemistry of Macromolecules
BIOL 4157/5157 Biochemistry of Macromolecules-Lab
BIOL 4167/5167 Biochemistry of Metabolism
BIOL 4177/51 Biochemistry of Metabolism- Lab
BIOL 1110 Biology for Majors-I
BIOL 1020 Biology for Non-Majors-II
Education
Ph.D. (1998) Lucknow University, Lucknow, India, and International Center for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
Positions Held
2005-present, Assistant Professor of Biochemistry, Department of Biological Sciences, East Tennessee State University, Johnson city, TN 37614
2000-2005, Research Associate, Boyce Thompson Institute for Plant Research, Ithaca, New York, 14853, USA
1998-2000, Post Doctoral Associate, Waksman Institute, Rutgers, The state University of New Jersey, New Jersey, 08854, USA
Students in Research
Graduate Students (MS):
Diwaker Tripathi: Will be joining the research group in Fall 2008. We are looking forward for his arrival at ETSU.
Kranthi Kumar Gampala: Will be joining Kumar Lab in Fall of 2008. We are eagerly waiting for his arrival to United States.
Undergraduate (BS):
Tazley Hotz : Joined my lab as a freshman. Tazley has recently started working in the lab and is in the process of identifying a specific project. Tazley was awarded SURF (Summer Undergraduate Research Fellowship) by ASPB to conduct research in my lab during Summer of 2007. http://www.etsu.edu/etsu/news_text.asp?Action=ListEvent&EventID=6423 http://www.etsu.edu/honors/international/newsarticle.asp?newsid=270. Recently Tazely was invited to present her research findings at the Plant Biology 2008 meeting held in Merida, Mexico. Abstract of her presentation could be seen at (http://abstracts.aspb.org/pb2008/public/P48/P48005.html).
Kajal Patel: A chemistry major at ETSU. She wishes to become a pharmacist. She received a "Student Faculty Collaborative Research Grant" from ETSU to conduct research in the field of SA signaling.
Yutika Patel: A chemistry major has joined my lab in summer of 2008. He aspires to become a Dentist.
Past Students:
Alexander Eddo: Is a first year MS student. He is studying the SA-signaling in Tobacco-TMV interactions. Received a "Graduate Studies Student Research Grant" from School of Graduate Studies, ETSU (http://www.etsu.edu/GRADSTUD/information/ResearchGrants2006-07.asp). Recently he presented his research at Appalachian Research Forum, 2007 for which he received a joint IInd place award. Alex has successfully defended his Masters thesis and moved on to England.
Poonam M. Sheth: Poonam studied the "Regulation of SABP2 by defense signals & Plant Tissue culture of tobacco, Tomato". She received "Student Faculty Collaborative Research Grant" from ETSU to study the regulation of SABP2 by defense signals. Poonam has graduated from ETSU and at present she is a project coordinator at Microbial insights, Rockville, TN 37853 (http://www.microbe.com).
John W. Sayne: Establishment of Suspension Cell culture from tobacco leaves and general support to lab activities. Jone is expected to graduate shortly. He aspires to become a teacher.
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Contact me (kumard@etsu.edu) for undergraduate or graduate research opportunities in my lab. Limited number of Graduate Assistantships for highly deserving candidates are available which covers their tuition fees and stipends. If you are interested in doing some cutting edge science feel free to contact me.