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

Chen, W., Gaikwad, A., Mukherjee, S.K., Choudhary, N.R., Kumar,  D., and Tewari, K.K. (1996) A 43 kDa DNA binding protein from the pea chloroplast interacts with and stimulates the cognate DNA polymerase. Nuc. Acids. Res. 24: 3953-3961 http://nar.oxfordjournals.org/cgi/reprint/24/20/3953

Kumar, D., Mukherjee, S., Reddy, M.K. and Tewari, K.K. (1995) A novel single stranded DNA-specific endonuclease from pea chloroplasts. J. Exp. Bot. 46: 767-776 

Reddy, M.K., Choudhary, N.R., Kumar, D., Mukherjee, S.K. and Tewari, K.K. (1994) Characterization and mode of in vitro replication of pea chloroplast OriA sequence. Eur. J. Biochem. 220: 933-941 http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1432-1033.1994.tb18697.x

Mukherjee, S.K., Reddy, M.K., Kumar, D. and Tewari, K.K. (1994) Purification and characterization of a eukaryotic type I topoisomerase from pea chloroplast. J. Biol. Chem. 269: 3793-3801 http://www.jbc.org/cgi/reprint/269/5/3793

Ramachandran, P., Kumar, D., Varma, A., Pandey, P.K. and Singh, R.P. (1992) Coleus viroid in India. Current Science 62: 271-272 http://www.ias.ac.in/j_archive/currsci/62/2/271-272/viewpage.html

Varma, A., Khetrapal, R.K., Vishwanath, S.M., Kumar, D., Maury, Y., Sharma, B. and Tyagi, M.C. (1991) Detection of Pea seed borne mosaic virus in commercial seeds of pea and germplasm of pea and lentil. Indian Phytopathology 44: 107-111

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.