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Genetically transformed lines of the elite indica rice cultivars, ADT38, ASD16, IR50 and Pusa Basmati1, constitutively over-expressing rice tlp encoding a thaumatin-like protein, have been evolved for management of rice sheath blight disease. The incorporation of tlp transgene in the genomes of T0 lines was ascertained by polymerase chain reaction and confirmed by Southern hybridization analyses. Expression of tlp in the putative transformants was confirmed by western blotting analysis. Stable inheritance of the transgene expression was studied up to T2 generation by western blotting analysis. The putative transformants and their progenies expressing tlp showed enhanced resistance against the sheath blight pathogen, Rhizoctonia solani, when compared to the non-transformed plants. The use of rice chi11, encoding a chitinase, as a co-transgene along with tlp produced a tlp–chi11 co-transformant that showed enhanced resistance against R. solani than the ones that express tlp or chi11 transgene alone. In addition to sheath blight resistance, the tlp or chi11 transgenic lines displayed significant levels of protection against the rice sheath rot pathogen, Sarocladium oryzae.

Should fruits of transgenic research on engineering resistance against crop diseases reach needy farmers, such resistance needs to be characterised thoroughly. Assessment of transgenic resistance conferred by over-expression of defence genes under field conditions or in greenhouse is a time-consuming process. It becomes often necessary, though laborious, to screen a huge population of putative transgenic lines for their resistance against a target disease. Most standard evaluation systems (SES) available for individual plant–pathogen interactions are applicable only to field conditions, and there has been a constant need for evolving a rapid laboratory method for assessment of efficacy of defence genes deployed against plant diseases. In this paper, we describe a high throughput, yet simple method for functional assessment of a rice chitinase gene chi11 known to confer resistance against Rhizoctonia solani, the rice sheath blight (ShB) pathogen. Accuracy of this method as compared with a SES already available for assessing field performance of test-varieties against ShB is discussed.