Isolation and functional characterization of a novel stress inducible promoter from pigeonpea (Cajanus cajan L)

The present study deals with isolation and characterization of a novel hybrid-proline-rich protein gene (CcHyPRP) promoter from pigeonpea. Real time PCR analysis revealed that CcHyPRP expression was strongly induced by dehydration, salt, Abscisic acid (ABA) and Salicylic acid (SA) treatments. The CcHyPRP promoter, isolated by genome-walking method, contained 1112 bp and showed the presence of various cis -regulatory elements necessary for tissue specific expression and stress responsiveness. Different 5' deletions of the promoter were generated and were used to drive the expression of beta-glucuronidase reporter gene (gusA) in Arabidopsis thaliana. Histochemical and fluorometric assays confirmed that GUS expression driven by the full-length fragment (1112 bp) was higher when compared to different deletion fragments. Under normal conditions, GUS expression was predominantly detected in the roots and hypocotyls of transformants, while under mannitol, NaCl, ABA and SA treatment conditions higher GUS expression levels were observed in the roots and leaves. However, the GUS expression was mostly confined to the roots of transformants carrying 477 and 300 bp promoter regions. The results amply indicate that CcHyPRP promoter is regulated by different stress factors, and as such the promoter can be deployed in genetic engineering of crop plants for enhanced abiotic stress tolerance.