Spatio-temporal expression of insecticidal gene (Cry1Ac& Cry2A) in pre existing lines of transgenic cotton was studied. Seasonal decline in expression of genes differed significantly among different cotton lines tested in the field conditions. The leaves of the Bt cotton plants were found to have the highest levels of toxin expression followed by squares, bolls, anthers and petals. Expression of the genes decreased consistently with the age of plants. Toxin expression in fruiting parts was not enough to confer full resistance against bollworms. The reduction in efficacy of transgenic cotton plants late in the season was attributed to reduction in promoter activity. For this purpose, Rubisco small subunit promoter was isolated from Gossypium arboreum that was further cloned upstream of Cry1Ac in expression vector pCAMBIA 1301. A local cotton cultivar was transformed with Cry1Ac driven by rbcS promoter. The same cotton cultivar was also transformed with Cry1Ac gene driven by 35SCaMV promoter to compare the expression pattern of insecticidal gene under two different promoters. The results showed that rbcS is an efficient promoter to drive Bt gene expression in cotton.

Abiotic stresses is a major limiting factor in plant growth. Drought is a serious problem that affects many regions of the world, decreasing the productivity of crops worldwide. Cotton is the most valuable textile fiber crop and second oilseed crop in the world. Agriculture is the largest sector of Pakistan's economy contributing 21% GDP. Fiber yield and lint quality is limited by drought stress after bloom. In the present work by using different molecular biological techniques six drought responsive transcripts and three full length genes have been identified from desi cotton. Their expression is also checked which showed significant over expression of these genes in drought stressed leaves as compared to control. Two genes were transformed into commercial cultivar of cotton. This work has a great impact on economy of Pakistan and will help to develop drought tolerant cotton varieties. It is need of time to develop drought tolerant crops as water shortage is becoming the major problem for the whole world.