Current status of tissue culture and genetic transformation research in cotton (Gossypium spp.)

Cotton (Gossypium spp.) is an economically very important fiber yielding crop, which is grown almost in sixty-five countries throughout the world. Like other crops, cotton also suffers from major biotic and abiotic stresses. In fact, the losses due to insect pests in cotton are enormous compared to other crops, thereby reducing the actual economic potential. It is a well-known fact that more than half of the total pesticide consumption across the world is utilized on controlling insect pests in this crop. Though conventional breeding and integrated pest management practices have resulted in improving/developing fiber quality, heat tolerance, CMS lines and yield, much success has not been reported with respect to biotic and abiotic stresses, especially insect pests due to the non-availability of genes conferring resistance within a cross-able gene pool. Thus, genetic engineering has become an inevitable tool in finding solutions to these problems and transfer of alien genes into commercially important cotton varieties in the last two decades. In fact similar to 81% of cotton grown throughout the world is genetically modified. Despite these achievements, several limitations still exist in achieving cotton transformation. In this review, we discuss the status of different regeneration and transformation methods in cotton along with the major factors that exert influence in developing cotton transgenics, besides the chronological progress made in tissue culture and cotton transformation technology.