## 1 Introduction  
Cotton (_Gossypium hirsutum_ L) is cultivated in more than 50 countries worldwide and the cotton crop is a major component of the economy of Pakistan as a highly valued cash crop [1]. Cotton cultivation in Pakistan faces a number of problems, such as insect pests, plant viruses and weeds. Traditionally, insect pests have been controlled by agrochemicals, but their widespread use poses human health and economic risks. In recent decades, the development of transgenic crops have created opportunities for major biotechnological breakthroughs in solutions to pest and pathogen management [2, 3]. Alternatives to agrochemicals, genetically modified (GM) crops expressing _cry_ alleles (Cry1 Ac, Cry1 Ab, Cry2 Aand Cry2 Ab) isolated from _Bacillus Huntingiensis_ (Bt) are grown widely on all continents [4; 5; 6; 7]. Spatio-temporal variations in Bt-Cry1 Ac endotoxin levels have been especially observed in transgenic cotton during the late stages of growth and development [8; 9]. Consistent expression levels of Bt-Cry1 Ac endotoxin in cotton plants throughout the growing season is essential, particularly in the most vulnerable organs and tissues to achieve sustainable management of insect pests including lepidopterans that cause extreme damage to cotton plants. The Bt-Cry1 Ac endotoxin has been reported to occur in higher levels in transgenic plants early in the season, compared to late-season cotton growth and mid to late-season development stages [10].  
Geminiviruses serve as a potential source of bidirectional gene promoters, regulatory enhancers, and cis-acting as well transcriptional regulatory elements that can be used to enhance transgene expression in transgenic plants [11; 12]. Additionally, geminiviral replicas can be used as viral vectors for plant genome-editing objectives [13; 14]. Previously, the geminivirus large intergenic region (LIR) has been explored as a gene targeting for homologous recombination in plant genome engineering [15; 16; 17; 18]. The DNA-A genome of monopartite begomoviruses possesses a LIR sequence that functions as a bidirectional promoter, essential for replication and expression of the viral genes, C1 (replication associated protein) and V1 (coat protein) [19; 20]. Recently, Cry1 Ac endotoxin expression in plants has been driven by plant promoters including the rbcS [10; 21], AoPR1 [22; 23], ats1A [24; 25], and maize ubiquitin-1 promoters [26].  
The objective of this study was to develop a local cotton variety that expresses the Bt-Cry1 Ac gene in green tissues only and at consistent levels throughout the growing season. For this purpose, a robust promoter from the 'Burewala' strain of CLCuKoV was selected and characterized [19] prior to evaluating its ability to drive the expression of Bt-Cry1 Ac gene. The expression cassettes containing Cry1 Ac gene driven by the CLCuKoV-Bu bidirectional promoters were constructed. Transient expression of Cry1 Ac promoter was evaluated initially in _Nicotian tabacum_ L. 'Rustica' after which the constructs were transformed into cotton 'MNH-786' using _Agrobacteriumum_-mediated transformation. The goal was to utilize the begomoviral bidirectional promoter to drive robust, stable, consistent expression of the Bt-Cry1 Ac gene in transgenic cotton plants.