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resistant to virus diseases will be available for commercial exploitation in due course of time. In addition, somaclonal mutants of tobacco, rice, wheat, barley, sugarcane, and maize possessing resistance to diseases have been isolated in several countries of the Region.
A
22.
The monoclonal antibody technique for identification of pathogens and for indexing materials is in use in a number of countries. In China, more than 50 kinds of hybridoma strains have been constructed which secreted various kinds of monoclonal antibodies to viruses, bacteria, cancer, etc. India is applying the monoclonal antibody technique for diagnosis and epidemiology of tungro virus of rice and other important viruses. The Central Potato Research Institute, Simla, India has been using monoclonal antibodies, c-DNA and enzyme linked immuno-sorbent assays (ELISA) for detecting and characterizing viruses of potatoes. Several other developing countries have also been using this technique coupled with ELISA tests to detect peanut viruses.
23.
India has characterized inducible gene products in chickpea following Ascochyta infection. In Pakistan, to breed chickpea cultivars resistant to Ascochyta blight, toxins synthesized by virulent strains of the fungus have been isolated, purified and biochemically characterized.
24.
As regards abiotic stresses, appropriate varieties and technologies have still to be developed to improve and exploit the vast rainfed, problem soil and marginal areas. China, India and the Philippines are using in vitro techniques for selecting, inducing, isolating and transferring salinity resistance in major crops. The lines selected in different countries should be shared with other countries for extensive testing and selection of productive and salinity resistant/tolerant varieties. A recent study has shown that a high level of salinity tolerance could increase rice productivity by 0.5 t/ha on 2 million ha of saline land in Southeast Asia alone.
Biofertilizers and Efficient Use of Nutrients
25.
Azolla-blue-green algae technology and microbial associative and non-associative biological nitrogen fixation (BNF) have not been exploited fully. Biotechnological manipulations have shown the way for developing efficient strains of both hosts and symbionts. In India, multi-infective rhizobial strains have been developed. In Pakistan, the mechanism of nitrogen fixation by a local plant, "Kallar" grass, has been analysed and effort is being made to transfer this ability into rice. In the Philippines, work is focussed on isolating and testing local strains of rhizobia, associative bacteria and blue-green algae for rice and corn, and actinomycetes for non-leguminous forest species. Ectomycorrhizal fungi have been isolated for important reforestation species and are being packaged as tablets for field application. Further, genetically engineered plants, as in the case of cassava for phosphorus utilization, can be extremely useful for exploiting nutrient deficient (e.g. Fe deficiency) or nutrient toxic soils (e.g. Al toxicity). Despite these promises, the development aspects of BNF and nutrient utilization in most developing countries is not geared to take advantage of this technology and needs to be strengthened.
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