Ph. D student working on low molecular weight antioxidants biosynthesis of sweetpotato KRIBB School of Biotechnology, University of Science and Technology (UST)
Sweetpotato [Ipomoea batatas (L.) Lam] is a unique nutritional starch crop containing high levels of low molecular weight antioxidants such as carotenoids and vitamin C in its storage roots. The sweetpotato Orange (IbOr) protein with a strong holdase chaperone activity is a crucial factor in not only controlling carotenoid biosynthesis, but also directly stabilizing photosystem II under various abiotic stress conditions. In our previous study, sweetpotato plants overexpressing IbOr showed increased tolerance to high temperature, salt and oxidative stress as well as accumulation of carotenoids. A single amino acid substitution from Arg to His in melon Or (CmOr) protein dramatically elevated carotenoid contents. Here, to examine whether the substitution of the conserved Arg to His in IbOr leads to carotenoid overaccumulation and environmental stress tolerance, we generated transgenic sweetpotato calli and plants overexpressing IbOr-R96H. As expected, the color of sweetpotato calli overexpressing IbOr-R96H turned white into dark-orange with remarkable improvement of total carotenoid (13-fold) and β-carotene (39-fold) levels compared to IbOr calli. In addition, IbOr-R96H calli exhibited enhanced tolerance to salt and heat stresses. Furthermore, the cambium layers of storage roots in IbOr and IbOr-R96H transgenic sweetpotato plants displayed a light-yellow and an orange color, respectively. The total carotenoid levels in storage roots of IbOr and IbOr-R96H plants were increased up to 4- and 16-fold compared to non-transgenic (NT) plants. Particularly, violaxanthin content in IbOr and IbOr-R96H plants was 6~10 and 10~19 times higher than that in NT. The further characterization of IbOr-R96H sweetpotato plants is under investigation in terms of various abiotic stress tolerance. Moreover, we are developing the IbOr-R96H sweetpotato plants using CRISPR-mediated base editing technique. Our results suggest that the manipulation of IbOr-R96H is a useful strategy to improve nutritional quality and protect plants from environmental stresses for sustainable food security in the face of climate crisis.
Coauthors: Ho Soo Kim – Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB);Chan-Ju Lee – KRIBB School of Biotechnology, University of Science and Technology (UST);Woo Sung Park – College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University;Mi-Jeong Ahn – College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University;Sang-Soo Kwak – University of Science and Technology (UST), Korea Research Institute of Bioscience and Biotechnology (KRIBB)