Overexpression of the Golden SNP-Carrying Gene Enhances Carotenoid Accumulation and Heat Stress Tolerance in Sweetpotato Plants.

Carotenoids function as photosynthetic accessory pigments, antioxidants, and vitamin A precursors. We recently showed that transgenic sweetpotato calli overexpressing the mutant sweetpotato ( [L.] Lam) gene (-), which carries a single nucleotide polymorphism responsible for Arg to His substitution at amino acid position 96, exhibited dramatically higher carotenoid content and abiotic stress tolerance than calli overexpressing the wild-type gene (-). In this study, we generated transgenic sweetpotato plants overexpressing - under the control of the cauliflower mosaic virus (CaMV) promoter via -mediated transformation. The total carotenoid contents of - storage roots (light-orange flesh) and - storage roots (light-yellow flesh) were 5.4-19.6 and 3.2-fold higher, respectively, than those of non-transgenic (NT) storage roots (white flesh). The β-carotene content of - storage roots was up to 186.2-fold higher than that of NT storage roots. In addition, - plants showed greater tolerance to heat stress (47 °C) than NT and - plants, possibly because of higher DPPH radical scavenging activity and ABA contents. These results indicate that - is a promising strategy for developing new sweetpotato cultivars with improved carotenoid contents and heat stress tolerance.