M. S. M. S. University Baroda, India
Ph.D M. S. University Baroda, India
University of California Berkeley
University of Minnesota, St Paul
Office: Lapham 140
Research InterestsFunctional and Ecological Genomics of sulfur metabolism in Rhizobia Rhizobia play an important role in sustainable agriculture by forming nitrogen fixing symbiosis with legumes. One of the main factors affecting microbial fitness in soils is competition for nutrients. In contrast to understanding on carbon, nitrogen, iron and phosphorus utilization, sulfur utilization in rhizobia is not well studied. In soils, S is mainly in the organic form, present as sulfonates and sulfate esters. In addition, the sulfur sources that the bacteria utilizes inside the plant host are likely to be organic. The long-term objective of our research is to charcaterize the genetic and regulatory mechanisms of sulfur metabolism in the soybean nodulating bacterium Bradyrhizobium japonicum and Rhizobium leguminosarum. In addition, we are interested in the role of organic sulfur utilization in the rhizobial survival and nodulation.
Quest for Biological Nitrogen Fixation in non-legumes Rice is the staple food for more than half of human population. Rice yields must be increased 30% by 2020. This will necessitate doubling the use of nitrogen (N) fertilizers that are made from fossil fuels and thus is neither economically nor environmentally sustainable. N-fixation provides an efficient and sustainable alternative to N fertilizers. Recent studies have revealed that rice has a natural ability to form association with rhizobia, bacteria that form N-fixing symbiosis with legumes. These observations have renewed interest in determining the possibility of extending N-fixation to rice. In order to realize this potential, however, it is necessary to understand the mechanisms of rhizobial colonization of rice. R. radiobacter IRBG74 is an aggressive colonizer of rice and can enhance its yields. Our current research aims to identify critical genetic determinants involved in the rice-rhizobial interactions in both rice and the bacteria.
Characterizing bacterial symbionts of native USA Mimosoideae legumes Many legumes belonging to Mimosoideae subfamily are native to USA and play an important role as forage and ornamental crops. They can grow in low-input and degraded ecosystems because of their ability to form symbiotic association with bacteria that fix atmospheric Nitrogen (N) in specialized organs called nodules. Native legumes are also a good target for generating biomass for production of biofuels. In contrast to crop legumes that harbor α-proteobacteria as symbiont, many bacteria isolated from Mimosoideae legumes belong to β-proteobacteria. However, not much information is available regarding the identities of bacteria that form nodules of Mimosoideae legumes native to USA. In collaboration with Dr. Jim Muir (Teaxs A &M University), Dr. Euan James and Dr. Janet Sprent (University of Dundee, UK), we are isolating and characterizing these bacterial symbionts.
Gehlot H. S, N. Tak, M. Kaushik, S. Mitra, W-M Chen, N. Poweleitt, D. Panwar, N. Poonar, R. Parihar, A. Tak, I. S Sankhla, A. Ojha, S. R Rao, M. F Simon, F. B dosReis Junior, N. Perigolo, A. K Tripathi, J. I Sprent, J.P.W. Young, E. K James and P. Gyaneshwar. 2013. An Invasive Mimosa in India does not adopt the symbionts of its native relatives.Ann. Bot. 112:176-196
Crook M, B., S. Mitra, J-M Ane, M. J. Sadowsky and P. Gyaneshwar. 2013. Complete genome sequence of Sesbania symbiont and rice growth promoting endophyte Rhizobium sp. strain IRBG74. Genome Announc. 1(6). doi:pii: e00934-13. 10.1128/genomeA.00934-13
Das S., S. Singh, S. Forst, M. McClelland, and P. Gyaneshwar. 2013. Characterization of an acid-inducible sulfatase in Salmonella enterica serovar typhimurium. Appl. Environ. Microbiol. 79: 2092-2095.
Gyaneshwar, P., A. M. Hirsch, L. Moulin, W-M. Chen, G. N. Elliott, C. Bontemps, P. Estrada-de los Santos, E. Gross, F. B. dos Reis Junior, J. I. Sprent, J. P. W. Young, and E. K. James. 2011. Legume nodulating betaproteobacteria: diversity, host-range and future prospects. Mol. Plant-Microbe Interact. 24.
Sugawara, M., G. R. Shah, M. J. Sadowsky, O. Paliy, J. Speck, A. W. Vail, and P. Gyaneshwar. 2011. Expression and functional roles of Bradyrhizobium japonicum genes involved in the utilization of inorganic and organic sulfur compounds in free-living and symbiotic conditions. Mol. Plant-Microbe Interact. 24: 451-457.
Sreevidya V. S., R. Hernandez-Oane, P. Gyaneshwar, M. Lara-Flores, J. K. Ladha, and P. M. Reddy. 2010. Auxin distribution pattern regulates the initiation and radial position of lateral root development of rice. Plant Sci. 178: 531-538
Cummings S. P., P. Gyaneshwar, M. Andrews, D. Humphry, G. N. Elliott, A. Nelson, C. Orr, D. Pettitt, G. R. Shah, S. Santos, H. B. Krishnan, P. Vinuesa, D. Odee, M. Moreira, J. I. Sprent, J. P. W. Young, and E. K. James. 2009. Nodulation of Sesbania species by Rhizobium (Agrobacterium) strain IRBG74 and other rhizobia. Environ. Microbiol. 11: 2510-2525.
Loh KD, Gyaneshwar P, Papadimitriou EM, Fong R, Kim KS, Zhou Z, Inwood W & Kustu S (2006). A new pathway for pyrimidine catabolism. Proc. Natl. Acad. Sci. USA 103: 5114-5119.
Gyaneshwar P, Paliy O, McAuliffe J, Popham DL, Jordan MI & Kustu S (2005). Sulfur and nitrogen limitation in Escherichia coli K12: specific homeostatic responses. J. Bacteriol. 187: 1074-1090.
Gyaneshwar P, Paliy O, McAuliffe J, Jones A, Jordan MI & Kustu S (2005). Lessons from E.coli genes similarly regulated in response to sulfur or nitrogen limitation. Proc. Natl. Acad. Sci. USA 102: 3453-3458.
Zimmer D, Paliy O, Thomas B, Gyaneshwar P & Kustu S (2004). Genome image programs: visualization and interpretation of Escherichia coli microarray experiments. Genetics 167: 2111-2119.
Gyaneshwar P, James EK, Reddy PM, & Ladha JK (2002). Herbaspirillum colonization increases growth and nitrogen accumulation in aluminium-tolerant rice varieties. New phytol.154: 131-146.
Gyaneshwar P, Naresh Kumar G, Parekh LJ & Poole PS (2002). Role of soil microorganisms in improving P nutrition of plants. Plant Soil 245: 83-93.
Gyaneshwar P, James EK, Mathan N, Reddy PM, Reinhold-Hurek B & Ladha JK (2001). Endophytic colonization of rice by a diazotrophic strain of Serratia marcescens. J. Bacteriol. 183: 2634-2645