Promoter of COR2-like gene is a stress inducible regulatory region in banana

A promoter is a crucial component in driving the expression of a transgene of interest for biotechnological applications in crop improvement and thus characterization of varied regulatory regions is essential. Here, we identified the promoter of COR2-like (codeinone reductase-like) from banana and characterized its tissue specific and stress inducible nature. MusaCOR2-like of banana is closely related to COR2 and CHR (chalcone reductase) sequences from different plant species and contains signature sequences including a catalytic tetrad typical of proteins with aldo-keto reductase activity. Transcript level of MusaCOR2-like was strongly induced in response to drought, salinity and exposure of signaling molecules such as abscisic acid, methyl-jasmonate and salicylic acid. Induction of MusaCOR2-like under stress strongly correlated with the presence of multiple cis-elements associated with stress responses in the P_{MusaCOR2-like} sequence isolated from Musa cultivar Rasthali. Transgenic tobacco lines harbouring P_{MusaCOR2-like}-GUS displayed visible GUS expression in vascular tissue of leaves and stem while its expression was undetectable in roots under control conditions. Exposure to drought, salinity and cold strongly induced GUS expression from P_{MusaCOR2-like}-GUS in transgenic tobacco shoots in a window period of 3H to 12H. Applications of salicylic acid, methyl-jasmonate, abscisic acid and ethephon also activate GUS in transgenic shoots at different period, with salicylic acid and abscisic acid being the stronger stimulants of P_{MusaCOR2-like}. Using P_{MusaCOR2-like}-GUS fusion and expression profiling, the current study sheds insights into a complex regulation of COR2-like, one of the least studied genes of secondary metabolite pathway in plants.