Characterization of the RsMYB1 Promoter Induced by Various Abiotic Stresses
2021
Kim, D.H. | Yang, J.H. | Rhee, J.H. | Lee, J.Y. | Lim, S.H.
Plants grown under stress conditions generate excessive reactive oxygen species resulting in cell death. Therefore, plants activate the protection mechanism via antioxidant accumulation. Anthocyanins are flavonoid-derived secondary metabolites with high antioxidant properties. In this study, we analyzed and characterized the promoter region of RsMYB1, a positive regulator of anthocyanin biosynthesis. The RsMYB1 promoter was designed with four different fragment lengths (MP1, -1034; MP2, -830; MP3, -633; and MP4, -430 bp), and then each RsMYB1 promoter region was fused into a GUS gene for Arabidopsis transformation. The expression patterns of the RsMYB1 promoter constructs were analyzed at different developmental stages and under various abiotic stresses. The GUS expression pattern steadily increased with plant growth, and coincided with enzyme activity and a histochemical GUS assay. In response to drought, salt, sucrose, and low temperature, the GUS transcript level was highly expressed in MP4 in parallel with GUS enzyme activity. These assays indicated that the proximal region (-430 to -1 bp) of RsMYB1 was the core sequence that was induced by salt and low temperature. The expression level of RsMYB1 in the leaves of radish was highly activated and was consistent with the anthocyanin content under salt and low temperature conditions. These results suggest that induction of the RsMYB1 gene can activate the biosynthesis of anthocyanins, which are expected to help plants adapt to stress conditions due to their antioxidant activity.
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