My interests and objectives are related to investigations on physiology and biochemistry of diseases of fungal, bacterial and viral origin and of pathogens with a bias on understanding the gene functions. This resulted in the establishment of a laboratory for stress physiology at the Central Rice Research Institute (CRRI), now renamed as ICAR – National Rice Research Institute (ICAR-NRRI), Cuttack, India. The contributions from my laboratory, during the early part of my career in continuity with my doctoral and post-doctoral periods, when many resistance genes were not known, arose from comparative physiology and biochemistry-based studies. These are evidenced by several publications, and led to increased knowledge on understanding the ways in which plants defend themselves against pathogen attack and growth regulation of tungro (a virus complex)-affected rice plants.
With the refinement of research priorities, propelled by developments in the field of rice biotechnology world over, I transformed my laboratory into a full-fledged Molecular Plant Pathology laboratory focusing on practical disease management through the use of molecular marker technology for understanding pathogen populations and usefulness of disease resistance genes, and for employing marker-assisted selection for disease resistance genes in crop improvement programmes. Select set of breeding lines with two popular rice cultivars introgressed with different combinations of bacterial blight resistance genes developed, serve as near-isogenic lines for utility as resistance donors in breeding programmes.
External funding for projects mobilized
The selection of CRRI as one of the four founder members of the global Asian Rice Biotechnology Network (ARBN) programme funded by the Asian Development Bank, the German Federal Ministry for Technical Cooperation (BMZ) and the Rockefeller Foundation, and coordinated by the International Rice Research Institute (IRRI), the Philippines under Indian Council of Agricultural Research (ICAR)-IRRI collaborative projects with me as the team leader provided opportunities for mobilizing funds to the tune of $190,000/- for the the execution of the project (1993-2002). In addition, ICAR supported the project (1999-2002) in the form of an operational grant though A.P. Cess Funds.
A Molecular Plant Pathology Laboratory was established at CRRI through the ARBN programme under the aegis of IRRI. As the molecular plant pathologist and the team leader of the ARBN programme, This facilitated the transfer of modern molecular tools required for DNA fingerprinting of rice pathogens and for marker-assisted selection for disease resistance genes in breeding lines from IRRI, the Philippines to ICAR-NRRI (CRRI), Cuttack, India.
Resistance to blast in rice was comprehensively investigated employing different models (varieties differing in their susceptibility, susceptibility induced by environmental factors such as nitrogen fertilization, nycto-temperature and resistance induced by incompatible avirulent races of the pathogen and by non pathogens, and by chemicals). Operation of different mechanisms of resistance (offered by epicuticular wax, free phenols and their oxidases, cell wall-bound phenols and by phytoalexin) expressed during pre- and post-penetrative stages of pathogen development as constitutive or inducible in rice was shown.
The causes of several morphological and physiological symptoms of tungro disease syndrome were identified through investigations on hormonal (cytokinin, abscisic acid, gibberellins) regulation and physiological alterations of the diseased plants. This pointed out the metabolic similarity between tungro and moisture-stressed plants.
Blast and bacterial blight diseases of rice are serious constraints for rice production in most rice-growing ecologies. Although many disease resistance genes have been recognized during the post-green revolution era, their usefulness for deployment through breeding programmes have not been precisely known. In research related to rice biotechnology, for the first time in the country, a base collection of bacterial blight and blast pathogens numbering nearly 1500 and 1000 isolates of bacterial blight and blast pathogens, respectively occurring in the rainfed ecosystem of eastern India was characterized using DNA fingerprinting in conjunction with the conventional pathotyping with improved set of differentials.
The ARBN project helped to improve our knowledge on pathogen population structures prevailing in different target locations, and to assess the usefulness of both bacterial blight and blast resistance genes. That the durability of resistance is enhanced when more than one resistance gene is stacked together in a host genotype was shown through disease trap nursery evaluations and artificial inoculations with different strains of the pathogens.
This has helped the associated plant breeders for developing several lines carrying bacterial blight resistance genes singly and in combinations in the background of the most popular rice cultivars IR 64 and Swarna that were otherwise susceptible to bacterial blight employing DNA marker-assisted selection (MAS) strategies for the first time in the country. Evaluation of these MAS-derived fixed lines with two or three resistance genes stacked together across the country through the All India Co-ordinated Rice Improvement Programme (AICRIP) proved their resistance to bacterial blight, not only in eastern India, but also in other parts of the country, with few exceptions. Similar approach for transferring blast resistance genes in two of the most popular rice varieties of the rainfed uplands (Vandana and Kalinga III) was pursued.
Established a functional molecular biology laboratory at the International Institute of Biotechnology and Toxicology in 2004 (Good Laboratory Practices [GLP] certified institution) in Chennai, India for testing genetically modified organisms and for undertaking work related with regulatory purposes.
With the superannuation from the regular government service, as an Independent Researcher, my interest in the functional aspects of disease resistance genes in plant immunity continues to be active, besides the consulting activities.