Overexpression of IbMPK3 increases low-temperature tolerance in transgenic sweetpotato

Sweetpotato is an important crop that is very sensitive to low temperatures. Mitogen-activated protein kinase (MAPK) is involved in plant growth and development and is responsive to many environmental stresses. IbMPK3 is strongly regulated by low-temperature stress. We studied the function of IbMPK3 and how it may enhance the adaptability of sweetpotato plants to low-temperature stress. Transgenic sweetpotato plants overexpressing IbMPK3 were generated, and three transgenic lines with the highest expression level of IbMPK3 were used for low-temperature tests. Transgenic plants exposed to low-temperature stress had less damage associated with higher photosynthesis efficiency and less cell membrane damage. IbMPK3-overexpressing transgenic plants could modulate reactive oxygen species (ROS) metabolism with lower levels of O-2(-) and H2O2 accumulation and higher enzymatic activities than WT plants. Transcript expression levels of some ROS-related genes (IbCAT, IbCu-ZnSOD, and IbCAT) and stress-responsive genes (IbP3B and IbCOR27) were significantly upregulated in transgenic plants compared to WT. These results indicate that IbMPK3 has an important role in sweetpotato response to low temperatures.