The sweet potato is very sensitive to low temperature. Our previous study revealed that IbMPK3-overexpressing transgenic sweet potato (M3) plants showed stronger low-temperature stress tolerance than wild-type plants (WT). However, the mechanism of M3 plants in response to low-temperature stress is unclear. To further analyze how IbMPK3 mediates low-temperature stress in sweet potato, WT and M3 plants were exposed to low-temperature stress for 2 h and 12 h for RNA-seq analysis, whereas normal conditions were used as a control (CK). In total, 3436 and 8718 differentially expressed genes (DEGs) were identified in WT at 2 h (vs. CK) and 12 h (vs. CK) under low-temperature stress, respectively, whereas 1450 and 9291 DEGs were detected in M3 plants, respectively. Many common and unique DEGs were analyzed in WT and M3 plants. DEGs related to low temperature were involved in Ca²⁺ signaling, MAPK cascades, the reactive oxygen species (ROS) signaling pathway, hormone transduction pathway, encoding transcription factor families (bHLH, NAC, and WRKY), and downstream stress-related genes. Additionally, more upregulated genes were associated with the MAPK pathway in M3 plants during short-term low-temperature stress (CK vs. 2 h), and more upregulated genes were involved in secondary metabolic synthesis in M3 plants than in the WT during the long-time low-temperature stress treatment (CK vs. 12 h), such as fatty acid biosynthesis and elongation, glutathione metabolism, flavonoid biosynthesis, carotenoid biosynthesis, and zeatin biosynthesis. Moreover, the interaction proteins of IbMPK3 related to photosynthesis, or encoding CaM, NAC, and ribosomal proteins, were identified using yeast two-hybrid (Y2H). This study may provide a valuable resource for elucidating the sweet potato low-temperature stress resistance mechanism, as well as data to support molecular-assisted breeding with the IbMPK3 gene.

In this study, the physical, chemical, structural, and antioxidant characteristics of selenium (Se)-enriched sweet potato leaves (SSPL) powder produced through shear breaking and superfine grinding were examined. The superfine grinding SSPL powder had a brighter color, smaller particle size, and spherical shape. The superfine grinding SSPL powder showed improved dispersibility and solubility but reduced liquidity. Superfine grinding destroyed the crystalline area and decreased the thermal stability, while Se application did not significantly change the ordered structure. Correlation analysis showed that superfine grinding could improve crude fiber, crude lipid, total flavonoids, total polyphenol, and significantly enhance the antioxidant activities compared to shear breaking. Se enrichment can enhance the content of the crude protein and the DPPH• scavenging activity and reducing power. The flavor characteristic was not altered with the different crushing methods and Se concentrations. SSPL powder could serve as a potential resource for a new solid beverage.