Genetic engineering towards improvement of rainfed lowland indica rice for disease and insect resistance

In order to meet the ever increasing demand of the burgeoning rice consuming population of South East Asia, the productivity of rice in rainfed lowland ecosystem needs to be seriously addressed as it constitutes vast majority of the rice growing area of South East Asia including Eastern India and Philippines. From among the biotic factors limiting the productivity of rice in such fragile ecosystem, sheath blight (Rhizoctonia solani) among diseases and yellow stemborer (Scirpophaga incertulas) among insect pests are important concerns in terms of their wide spread occurrence as well as the crop yield loss incurred to their infestation. Conventional breeding has not so far been successful for development of lowland rice resistant to these two major pest mainly due to the lack of resistant donors in the available rice gene pool. Alternatively, plant genetic transformation has been successfully employed to develop sheath blight and stem borer resistant rice (Lin et al, 1995; Datta et al, 1998; Alam et al, 1998). Two lowland indica rice varieties (Vaidehi-1 and Tulsi suitable for Eastern India) were transformed with both chilinase and cry1A(b) genes conferring resistance to sheath blight and stem borer, respectively by biolistic as well as Agrobacterium mediated transformation. As seen from the southern analyses, the primary transgenics (To) from Agro-tranformation showed simple pattern of transgene(s) integration unlike multiple copies and rearrangements as observed in the transgenics from biolistic experiments. The expression of chitinase transgene was confirmed by western blot analysis as well as chitinase enzyme assay exhibiting over production of the enzyme compared to non-tranformed control. The plants are in T1 for inheritance studies of transgene(s) and further evaluation of their reactions to the pests under epiphytotic condition in containment facilities