Application of Biotechnology as a Breeding Tool in Crop Improvement for Drought Tolerances

Plant breeding has to be considered one of the longest, continuous activities conducted by humans and the evolution of the human civilizations paralleled with the successes of plant breeding. Plant breading have different role or objective that improve plant productivity for various purpose those are breading for Drought tolerances improvement of crop, Breeding for Salt tolerance improvement of crop, Breeding for disease resistance improvement of crop, Breeding for insect resistance improvement of crop, Breeding for weeds resistance varieties development of crop, Breeding for quality crops improvement, Breeding for quality protein content improvement of crop and Breeding for increasing grain and biomass yield of crop (Arnel ., 2011; In general approximately onethird of the Earth's land area is arid or semi-arid and badly affecting the crop productivity and its accounting for about 70% reductions in yield of our total cereal crops The definition of drought tolerance is the ability of the plant or crop to survive in water limited conditions or environment. However, inducing drought tolerance in crop plants is not a simple task rather one of the most difficult challenges currently the breeders face. Because of due to its polygenic nature of drought that means drought is genetically control by many genes with low heritability and high G E interactions Without any interference of mankind and any kind of technology Plants have different mechanisms to survive drought in different environment by themselves the most one that plants use to survive Abstract: Plant breeding has to be considered one of the longest and continuous activities conducted by human for improvement of crops for different trait, drought stress tolerance crop breeding is one of human breeding objective and it is one of the major yield constraints for different type of crops. Traditionally for developing drought tolerant cultivars conventional based selection is practiced. Although this approach is effective for several years but conventional methods are time consuming and labour intensive. Biotechnology tool such as Identification of drought related quantitative trait loci (QTLs) coupled with marker assisted selection, Transgenic and "omics" technologies promise to make progress in breeding for drought tolerance through a more fundamental understanding of underlying mechanisms of drought tolerance and identifying potential candidate genes so in these review cover both conventional and modern biotechnology tool that are used for drought tolerance crop improvement and the new approaches provide opportunities to direct the continued breeding of genotypes giving stable yields under drought stress.