The protective effect of cold acclimation on the low temperature stress of the lotus (Nelumbo nucifera)

Abstract

This study compared the protective effect of cold acclimation on the cold tolerance in the lotus (Nelumbo nucifera). The cold acclimation increased the sprouting rate and leaf expansion rate of the lotus by about 36% at 0 °C, and the cold acclimation could enhance the levels of the stress related osmolytes including higher proline, soluble protein, and soluble sugar contents. The electrolyte leakage and lipid peroxidation level of the control samples increased significantly, but these indices did not change significantly in the cold acclimation group during low temperature stress. Furthermore, the cold acclimated rhizomes had higher antioxidant enzyme activities and a more stable ROS homeostasis response to the low temperature stress. Some stress-related genes were significantly up-regulated after the cold acclimation, especially the antioxidase related genes (CAT1, GPX, APX and MSD) were up-regulated nearly five times higher than that of the control group at the 0 °C condition. Additionally, the ICE1-CBF-COR pathway was involved in the lotus cold acclimation process. These results suggested that cold acclimation can obviously improve the stress tolerance of the lotus by the stable ROS homeostasis, enhance the antioxidant enzyme activity, regulate the stress-related gene expression and alleviate the stress damage.