- Thirukkural,
1038 (31 B.C.).
Sridhar's
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.
.
External funding for projects mobilized
The selection of CRRI as one of the three founder members of the 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.
Rice biotechnology
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, I brought into use the modern molecular tools required for DNA fingerprinting of rice pathogens and for marker-assisted selection for disease resistance genes.
Major contributions
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, 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 facilitated 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 present in combination 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 employing DNA marker-assisted selection.
These lines are in the final stages of field evaluation.
Similar approach for transferring blast resistance genes
in two of the most popular rice varieties of rainfed
uplands (Vandana and Kalinga III) is underway.
Back to Top
