Biotechnology as a tool in combating abiotic stress in veget-able crops with special reference to cowpea: a review

Abiotic stresses including salinity, drought, and temperature extremes are serious threats to the crop survival which somehow affect the crop yield. Several traditional methods are practiced for sustainable crop productivity but with the increasing abiotic stress due to changing climatic conditions and increasing pressure of population the traditional techniques of overcoming abiotic stress are not able to meet the demands. Hence, genetic engineering for developing stress tolerant plants, based on the introduction and pyramiding of genes that are known to be involved in stress response and tolerance and may provide a promising track towards improving crop varieties is required. Far beyond efforts have been made to develop varieties by engineering regulatory machineries involving transcription factors as a tool for controlling the expression of stress responsive genes. But the complete process of generating transgenic cultivars also depends on the successful transformation and proper incorporation and finally expression of the transgene. Evaluation of the transgenic plants under stress conditions, and understanding the physiological effect of the inserted genes at the whole plant level remain as major challenges to overcome. This review focuses on the conventional and new improved biotechnological methods for the improvement of abiotic stress tolerance in plants with a special reference to vegetable cowpea.