Review On: Impact of Genetic Engineering in Biotic Stresses Resistance Crop Breeding

Abstract
Genetic engineering is recombinant DNA technology that involves artificial addition, deletion or rearrangement of sequences of bases in DNA to alter form and function of organism. It complement plant breeding efforts by increasing the diversity of genes and germplasm available for incorporation into crops and by shortening the time required for the production of new varieties and hybrids. As the conventional breeding is restricted to sexually compatible crop species, time intensive and random process the genetic engineering is an alternative method to develop promising varieties with higher resistance to biotic stresses. Genetic engineering facilitates development of biotic stress resistant crops by expressing bacterial δ-endotoxins and vegetative insecticidal proteins, plant genes like lectins, protease inhibitors, RNA interference and genome editing through CRISPR Cas9. Bt-crops (maize, cotton Tobacco, Soyabean and etc), Bacillus thuringiensis (BT) are insect-resistant crops and the most outstanding achievements through genetic engineering of insecticidal protein coding genes from soil bacterium B. thuringiensis. Several studies indicated that genetically modified crops have reduced pesticide quantity by 37% and pesticide cost by 39% and on average crop yields increased by 21%. Transgenic lines of banana and tomato have showed resistance to Banana Xanthomonas wilt (BXW) and Fusarium wilt, respectively. In summary, Genetic engineering has played pivotal role in developing biotic resistance cultivars and cultivation area of these crops is growing fast each year, which indicates understanding and applying this new technologies offer more effective solutions against evolving biotic stress.