Stacking of cry1Ab and Chitinase Genes in Commercial Cotton Varieties through Crossing

Cotton (Gossypium hirsutum) is one of the most important fiber crops with a raw material value of $5.5 billion per year worldwide. Cotton breeders with the help of conventional breeding programs have improved the cotton germplasm for resistance to pests and pathogens. However, there has been little success in producing cotton lines resistant to biotic stresses, due to limited cotton germplasm with adequate resistance to biotic stresses, especially pests and diseases. In this study, cry1Ab (resistance to cotton bollworm) and chitinase (resistance to cotton Verticillium wilt) genes were transferred to Iranian commercial cotton varieties (Varamin, Khordad, Sahel, and Bakhtegan), by crossing transgenic lines containing cry1Ab and chi transgenes with Iranian commercial varieties. To recover genetic background of commercial varieties, the obtained progenies were backcrossed with own commercial parent. The progenies of backcrosses were assessed by western blot and PCR analysis. Insect and fungus in vitro bioassay showed resistance against cotton bollworm and Verticillium dahliae in plants containing the stacked transgenes. According to the results, cry1Ab and chi genes were successfully transferred and stacked in Iranian commercial cotton varieties. Also, plants with two transgenes and plants with one transgene were protruded to BC1 and BC2 generations, respectively.