Dr. Sheo Shankar Pandey
In the ongoing battle between plants and microbial pathogens, their molecular-level struggle determines disease outcome. Both phytopathogenic bacteria and host plants have evolved intricate strategies in this war. Our research focuses on unraveling the genetic, molecular, and biochemical basis of virulence in phytopathogenic bacteria and understanding the corresponding host responses. By employing genetic, biotechnological, and microbiological tools, we aim to identify virulence factors and explore the bacterial secretion systems and their role in releasing these factors within host plants
Fig. 1. Simplified schematic presentation of plant and phytopathogenic bacteria interactions. Phytopathogenic bacteria have evolved sophisticated strategies to infect host plants, employing multilayered mechanisms. The bacterial pathogen's virulence genes encode virulence factors, enabling successful invasion and colonization of the host, leading to disease. Bacteria secrete toxins and extracellular hydrolytic enzymes through the T1SS (type 1 secretion system) and T2SS (type 2 secretion system), respectively, to target plant cells and facilitate the infection process. In response, plants have developed multiple layers of defense responses. Plant receptors recognize bacterial PAMP/MAMP (microbial/pathogen-associated molecular patterns), triggering PTI (PAMP-triggered immunity). To counteract PTI, bacteria inject effectors via the T3SS (type 3 secretion system) to interfere with PTI, thereby inducing ETI (effectors triggered immunity). The activation of PTI and ETI triggers a hypersensitivity response, which serves to restrict bacterial propagation within the host.
Furthermore, we are keen on studying bacterial and viral diseases specifically affecting plants of economic importance in Northeast India. The northeastern regions, including Assam, are renowned ecological hotspots with remarkable mega-biodiversity. Citrus, mulberry, and medicinal plants play a vital role in the local economy but face challenges from various bacterial and viral infections. Our objectives are not limited to, but currently include the following areas of exploration:
- Lifestyle and Virulence Strategies of Vector-Borne Phloem-Limited Bacteria. Phloem-limited bacteria cause severe plant diseases transmitted by insect vectors, posing challenges for control strategies. Candidatus Liberibacter asiaticus (CLas), a phloem-limited bacterium transmitted by Asian citrus psyllids, induces devastating Huanglongbing (HLB) disease in citrus. In our lab, we study CLas-triggered immune responses in citrus using microbiological genetics and omics approaches. Exploring the secretion system and genetic diversity of phloem-limited bacteria, we aim to develop strategies for managing these plant diseases.
- Citrus Canker. Citrus canker poses a significant threat to citrus cultivation worldwide, including major citrus-growing regions in India such as Northeast, Nagpur, and Punjab. Within our research, we aim to identify and characterize the novel virulence factors in canker causing phytopathogenic bacterium Xanthomonas citri pv. citri. We are exploring the mechanisms by which the bacterium interacts with the host plants, as well as the defense mechanisms employed by the plants to combat the infection. Our research efforts ultimately aim to contribute to the development of effective control strategies for canker management.
- The Bacterial and Viral Diseases of Mulberry and Medicinal Plants. Mulberry is essential to the sericulture industry, providing food for silkworms and valuable fruit for diverse products. However, bacterial blight and mulberry mosaic virus infections continue to impact mulberry cultivation in India. Similarly, microbial infections pose obstacles to the cultivation of medicinal plants, which hold great potential for farmers' economic development. Our lab is interested in investigating microbial diseases in mulberry and medicinal plants. We aim to understand infection processes, virulence strategies, and host responses to Pseudomonas syringae pv. mori and mosaic virus on mulberry plants. We seek to explore the microbial biodiversity associated with mulberry and medicinal plants, as it is essential for gaining a deeper understanding of the diseases and microbial ecology to develop effective disease management strategies. Additionally, we are interested in studying emerging bacterial and viral diseases in mulberry and medicinal plants.
Academic:
Postdoctoral Research Associate | CREC, Department of Microbiology and Cell Science, University of Florida, FL, USA | 2017-2022 |
PhD | Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India | 2010-2017 |
MSc | Banaras Hindu University, Varanasi, India | 2007-2009 |
Employment:
Ramalingaswami Faculty | Institute of Advanced Study in Science & Technology (IASST), Guwahati, India | 2023-Present |
Senior Biological Scientist | CREC, Department of Microbiology and Cell Science, University of Florida, FL, USA | 2022-2023 |
Honors/Awards:
Ramalingaswami Re-entry Fellowship 2021, Department of Biotechnology, Ministry of Science and Technology, Government of India. | 2022 |
Outstanding student abstract award, American Society for Microbiology at “ASM-Microbe 2016”, Boston, MA, USA. | 2016 |
DBT Travel Grant. Department of Biotechnology, Ministry of Science and Technology, Government of India. To attend ASM-Microbe 2016, Boston, MA, USA | 2016 |
EMBO conference travel grant, European Society of Clinical Microbiology and Infectious Diseases (ESCMID) to attend “Bacterial Morphogenesis, Survival, and Virulence: Regulation in 4D-2016”. | 2016 |
ARS-NET, Basic Plant Science, Agricultural Scientists Recruitment Board (ASRB), India | 2010 |
CSIR-JRF, Life Sciences, Council of Scientific & Industrial Research, India | 2009 |
ICMR-JRF, ICMR Fellowship Scheme, Indian Council of Medical Research, New Delhi, India | 2009 |
GATE-2009, Life Sciences (99.64 percentile) | 2009 |
Memberships of scientific societies
Early career member, American Phytopathological Society, St. Paul, MN, USA. 2019-present
Indian Citriculture Society. Life Member
Editorial Responsibilities
Review Editor: Frontiers in Plant Science - Since Nov 2021
Frontiers in Microbiology - Since Nov 2021.
Frontiers in Microbiomes - Since Oct 2022.
Guest editor: Horticulturae 2023.
Selected national/ international conferences attended.
- *International Symposium on Plant Microbe Interactions. November 2023. MBBT, Tezpur University, Tezpur, Assam, India. *Chaired a session
- *Asian Citrus Congress October 2023, Nagpur, Maharashtra, India. *Co-chaired the technical session-3B: Current approaches in citrus health management, insect-pest & disease surveillance and diagnostic tools.
- *2nd Congress of International Society for Citrus Huanglongbing and Phloem-Colonizing Bacterial Pathosystems (IS-CHPP) Oct 2022, Clearwater, FL, USA. * Moderated the session: Epidemiology and disease control.
- 7th Xanthomonas Genomics Conference, Jun 2022, Clearwater, FL, USA.
- Molecular Intricacies of Plant Associated Microorganisms (MIPAM-2022). CDFD-India (Virtual meeting).
- Plant Health-2021. American Phytopathological Society, St. Paul, MN, USA (Virtual meeting).
- Plant Health-2019; Cleveland Ohio, USA. American Phytopathological Society, St. Paul, MN, USA.
- “Bacterial Morphogenesis, Survival and Virulence: Regulation in 4D-2016”; Thiruvananthapuram, Kerala, India. European Molecular Biology Organization (EMBO), Heidelberg, Germany.
- “ASM-Microbe 2016”, Boston, MA, USA. American Society for Microbiology, Washington, DC, USA.
- MCB-75; Bengaluru, Karnataka, India, Indian Institute of Science (IISc) Bengaluru, India.
- 4th International Conference on Bacterial Blight (ICBB), Hyderabad, India.
Articles:
Pandey, S. S., Li, J., Oswalt, C., Wang, N. 2024. Dynamics of Candidatus Liberibacter asiaticus growth, concentrations of reactive oxygen species, and ion leakage in HLB-positive sweet orange. Phytopathology. DOI: 10.1094/PHYTO-08-23-0294-KC.
Pandey S. S. 2023. The role of iron in phytopathogenic microbe–plant interactions: insights into virulence and host immune response. Plants. 12 (17), 3173. DOI: 10.3390/plants12173173.
Pandey, S. S., Xu, J., Diann, S. A., Li, J., Wang, N. 2023. Microscopic and transcriptomic analyses of early events triggered by Candidatus Liberibacter asiaticus in young flushes of HLB-positive citrus trees. Phytopathology. 113 (6), 985-997. DOI: 10.1094/PHYTO-10-22-0360-R.
Ribeiro, C., Xu, J., Hendrich, C., Pandey, S. S., Yu, Q., Gmitter, F., Wang, N., 2023. Seasonal transcriptome profiling of susceptible and tolerant citrus cultivars to citrus Huanglongbing. Phytopathology. 113(2):286-298. DOI: 10.1094/PHYTO-05-22-0179-R.
Ma, W.†, Pang, Z.†, Huang, X.†, Xu, J.†, Pandey, S. S.†, Li, J.†, Diann, S. A.†, Vasconcelos, F. N. S., Hendrich, C., Huang, Y., Wang, W., Lee, D., Wang, N., 2022. Citrus Huanglongbing is an immune-mediated disease that can be treated by mitigating reactive oxygen species triggered cell death of the phloem tissues caused by Candidatus Liberibacter asiaticus. Nature Communications. 13, 529. DOI: 10.1038/s41467-022-28189-9.
†equal contribution
Pandey, S. S. †, Connor, H. G. †, Andrade, M. O., Wang, N., 2022. Candidatus Liberibacter: From Movement, Host Responses, to Symptom Development of Citrus HLB. Phytopathology. 112(1):55-68. DOI: 10.1094/PHYTO-08-21-0354-FI.
†equal contribution
Pandey, S. S.*, Chatterjee, S.*, 2022. Insights into the cell-cell signaling and iron homeostasis in Xanthomonas virulence and lifestyle. Phytopathology. 112(2):209-218. DOI: 10.1094/PHYTO-11-20-0513-RVW.
*Co-corresponding author
Bin, H., Rao, M. J., Deng, X., Pandey, S. S., Connor, H. G., Ding, F., Wang, N., Xu, Q., 2021. Molecular signatures between citrus and Candidatus Liberibacter asiaticus. PLOS Pathogens. 17(12): e1010071. DOI: 10.1371/journal.ppat.1010071.
Teper, D., Pandey, S. S., Wang, N., 2021. The HrpG/HrpX Regulon of Xanthomonads—An Insight to the Complexity of Regulation of Virulence Traits in Phytopathogenic Bacteria. Microorganisms. 9(1), 187. DOI: 10.3390/microorganisms9010187.
Pandey, S. S., Vasconcelos, F. N. d. C., Wang, N., 2021. Spatiotemporal dynamics of Candidatus Liberibacter asiaticus colonization inside citrus plant and Huanglongbing disease development. Phytopathology. 121(6): 921-928. DOI: 10.1094/PHYTO-09-20-0407-R.
Teper, D., Xu, J., Pandey, S. S., Wang, N., 2021. PthAW1, a transcription activator-like effector of Xanthomonas citri subsp. citri, promotes host specific immune responses. Molecular Plant-Microbe Interactions. 34(9): 1033-1047. DOI: 10.1094/MPMI-01-21-0026-R.
Pandey, S.S., Wang, N., 2019. *Targeted Early Detection of Citrus Huanglongbing Causal Agent ‘Candidatus Liberibacter asiaticus’ Before Symptom Expression. Phytopathology. 109(6): 952-959. DOI: 10.1094/PHYTO-11-18-0432-R.
*editor’s pick.
Javvadi, S.†, Pandey, S.S.†, Mishra, A., Pradhan, B.B., and Chatterjee, S., 2018. Bacterial cyclic β‐(1, 2) ‐glucans sequester iron to protect against iron‐induced toxicity. EMBO-Reports. 19(1):172-186. DOI: 10.15252/embr.201744650.
†equal contribution
Pandey, S.S., Patnana, P.K., Padhi, Y., Chatterjee, S., 2018. Low‐iron condition induces the hypersensitive reaction and pathogenicity hrp genes expression in Xanthomonas and is involved in modulation of hypersensitive response and virulence. Environmental Microbiology Reports. 10(5):522-531. DOI: 10.1111/1758-2229.12650.
Pandey, S.S., Patnana, P.K., Rai, R., Chatterjee, S., 2017. Xanthoferrin, the α ‐hydroxycarboxylate‐type siderophore of Xanthomonas campestris pv. campestris, is required for optimum virulence and growth inside cabbage. Molecular Plant Pathology. 18(7): 949–962. DOI: 10.1111/mpp.12451.
Pandey, S. S., Singh, P., Samal, B., Verma, R. K., Chatterjee, S., 2017. Xanthoferrin siderophore estimation from the cell-free culture supernatants of different Xanthomonas strains by HPLC. Bio-protocol. 7 (14): e2410. DOI: 10.21769/BioProtoc.2410.
Pandey, S.S., Patnana, P.K., Lomada, S.K., Tomar, A., Chatterjee, S., 2016. Co-regulation of Iron Metabolism and Virulence Associated Functions by Iron and XibR, a Novel Iron Binding Transcription Factor, in the Plant Pathogen Xanthomonas. PLOS Pathogens. 12(11): e1006019. DOI: 10.1371/journal.ppat.1006019.
Patent:
Chatterjee, S., Pandey, S.S, 2020. Xanthoferrin, the α-hydroxycarboxylate-type siderophore, production from siderophore overproducing mutant strain of xanthomonads and utilization as iron sequestering agent for the protection against iron overload disorders. India Patent filed. Application No. 202041028231.
Selected presentations in national/ international conferences
Pandey, S.S., 2023. Huanglongbing (HLB): Unraveling the Citrus Catastrophe – Understanding Virulence Mechanisms, Challenges in Management, and Strategies for Control. International Symposium on Plant Microbe Interactions. MBBT, Tezpur University, Tezpur, Assam, India
Pandey, S.S., 2023. Huanglongbing (HLB): The citrus disease of greatest devastation- obstacles and approaches to control. Asian citrus congress. Nagpur, Maharashtra, India
Pandey, S.S., Xu, J., Achor, D.S., Li, J., Wang, N. Oct 2022. Dynamics of early events triggered by Candidatus Liberibacter asiaticus movement in young flushes of HLB-positive citrus trees. 2nd Congress of International Society for Citrus Huanglongbing and Phloem-Colonizing Bacterial Pathosystems (IS-CHPP), Clearwater, FL, USA.
Pandey, S.S., Wang, N. 2022. Biology of infection process, Huanglongbing (HLB) disease development and control strategies. MIPAM-2022. CDFD-India (Virtual meeting).
Pandey, S.S., Xu, J., Wang, N., 2021. Spatiotemporal dynamics of in planta Candidatus Liberibacter asiaticus movement, host response and Huanglongbing disease development. Plant Health-2021. American Phytopathological Society, St. Paul, MN, USA (Virtual meeting).
Pandey, S.S., Wang, N., 2019. Targeted early detection of citrus Huanglongbing causal agent ‘Candidatus Liberibacter asiaticus’ before the symptoms expression. Plant Health-2019; Cleveland Ohio, USA. American Phytopathological Society, St. Paul, MN, USA.
Pandey, S. S., Chatterjee, S., 2016. Co-regulation of Xanthomonas campestris virulence functions by iron and a novel iron binding transcription factor, XibR. “Bacterial Morphogenesis, Survival and Virulence: Regulation in 4D-2016”; Thiruvananthapuram, Kerala, India. European Molecular Biology Organization (EMBO), Heidelberg, Germany.
Pandey, S. S., Chatterjee, S., 2016. Co-regulation of Xanthomonas campestris Iron Homeostasis, Chemotaxis and Motility by Accessible Iron and a Novel Iron-Responsive Transcriptional Regulator XibR. “ASM-Microbe 2016”, Boston, MA, USA. American Society for Microbiology, Washington, DC, USA.
Pandey, S. S., Javvadi, S., Chatterjee, S., 2015. Bacterial β-(1, 2)–glucan sequester, and reservoir the iron and xibR regulates multiple functions required for iron homeostasis and virulence. MCB-75; Bengaluru, Karnataka, India, Indian Institute of Science (IISc) Bengaluru, India.
Pandey, S. S., Chatterjee, S., 2013. Role of Iron and Secreted Virulence Functions in Xanthomonas Virulence. 4th International Conference on Bacterial Blight (ICBB), Hyderabad, India.
- Understanding the virulence mechanism of Candidatus Liberibacter asiaticus on citrus and developing disease control strategies. DBT Ramalingaswami fellow grant.
Sreezana Gautom Project Associate-I
Debosmita Saha Master's Student (Winter trainee)
Our lab focuses on research in the fields of Plant Microbiology, Bacteriology, and Microbial Genetics. If you have a genuine interest in these areas and are driven to contribute to cutting-edge research, we encourage you to email your resume to "sshankar.pandey@iasst.gov.in" or “sheoshankar.bhu@gmail.com” along with a concise paragraph describing your research interests. We have a preference for candidates with external fellowships such as DBT/CSIR/ICMR/UGC-JRF. For guidance on admission and joining procedures, we recommend candidates refer to the rules and regulations of IASST, Guwahati.