Toxicity effects of zinc supply on growth revealed by physiological and transcriptomic evidences in sweet potato (Ipomoea batatas (L.) Lam).

Zinc toxicity affects crop productivity and threatens food security and human health worldwide. Unfortunately, the accumulation patterns of zinc and the harmful effects of excessive zinc on sweet potato have not been well explored. In the present research, two genotypes of sweet potato varieties with different accumulation patterns of zinc were selected to analyze the effects of excessive zinc on sweet potato via hydroponic and field cultivation experiments. The results indicated that the transfer coefficient was closely related to the zinc concentration in the storage roots of sweet potato. Excessive zinc inhibited the growth of sweet potato plants by causing imbalanced mineral concentrations, destroying the cellular structure and reducing photosynthesis. Furthermore, a total of 17,945 differentially expressed genes were identified in the two genotypes under zinc stress by transcriptomic analysis. Differentially expressed genes involved in the absorption and transport of zinc, defense networks and transcription factors played important roles in the response to zinc stress. In conclusion, this study provides a reference for the selection of sweet potato varieties in zinc contaminated soil and lays a foundation for investigating the tolerance of sweet potato to excessive zinc, which is meaningful for environmental safety and human health.

Effect of Maltodextrin on the Physicochemical Properties and Cooking Performance of Sweet Potato Starch Noodles.

Maltodextrin (MD), the hydrolyzed starch product, is a promising alternative ingredient to improve the quality of starch-based foods. The effects of MD on the physicochemical, microstructural, and cooking properties of sweet potato starch (SPS) noodles, as well as the mechanism of SPS-MD interactions, are discussed. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results indicated that MD at a suitable concentration can improve the ordered structure of SPS-MD gels. The cooking loss showed lower values of 1.47−2.16% at 0.5−2.0 wt% MD. For the texture properties, an increase in hardness and chewiness occurred at first with the addition of MD, followed by a decreasing trend, showing a maximum value at 2.0 wt% of MD. The pasting and thermal results verified the increased stability of the starch granules with MD < 3 wt%. Additionally, SPS formed a solid-like gel with MD, and the main interaction forces between SPS and MD were hydrogen bonding. The scanning electron microscopy results revealed that the higher concentrations of MD (>3 wt%) loosened the gel structure and markedly increased the pore size. These results help us to better understand the interaction mechanism of the SPS-MD complex and facilitate the development of SPS-based gel products.