Regulation behavior of RSuS-1 promoter using uidA gene in rice (Oryza sativa)

Abstract

The main objective of this study was to characterize the expression pattern and strength of Rice Sucrose Synthase promoter in rice genome. The expression pattern and strength of Rice Sucrose Synthase-1 promoter (pRSuS-1) both qualitatively and quantitatively in different plant tissues was done by ligating to gusA gene. To confirm its tissue specific expression driven by pRSuS-1, in another construct, a constitutive promoter Cauliflower Mosaic Virus (CaMV) 35S was also fused to the same reporter gene. The chimeric genes were introduced into a rice cultivar mediated by Agrobacterium tumefaciens while using hygromycin sequence as a selectable marker agent. Gus specific activity generated by the promoters was quantified using fluorometric method in the vegetative tissues such as leaves, stem, roots, seed coat and seed endosperm+embryo. The results demonstrated that the expression level produced by CaMV 35S promoter was roughly tenfold and twofold higher as per expected than pRSuS-1 and pRSuS-2 sequences in the leaves, roots, seed coat and stem, respectively. Gus specific expression by pRSuS-1 and pRSuS-2 in the seed endosperm+embryo was negligible. The overall activity of pCaMV 35S in the whole plant vegetative tissues was still three-fold greater. Also, a novel modification in the GUS staining technique of whole rice plant tissues has also been reported. The histochemical activity generated by RSuS-1 was detected in all of the plant parts used except for the seed embryo and endosperm and in this way, confirmed the environmentally safe gene expression of this useful promoter from consumer's point of view.