Effects of High Temperature on the Antioxidant Enzymes and Chlorophyll Fluorescence Parameters of Saccharina japonica

Abstract:

The aim of this study was to identify the effects of high temperature (25℃) on the activity of antioxidant enzymes, the chlorophyll content, and the chlorophyll fluorescence parameter of Saccharina japonica young sporophytes. Samples were taken every 4 h over a 48 h period. The major results included: (1) after 12 h culture the content of soluble proteins of the 25℃ group reached the maximum value that was 37.9% higher than initial level (P<0.05). (2) MDA content of the 25℃ group increased over the time and reached the highest value after 48 h, which was significantly different from the control group (P<0.05). (3) The chlorophyll content of the 25℃ group decreased during prolonged culture, the lowest value appeared after 48 h and was 38.5% lower than the initial level (P<0.05). (4) At high temperature the POD activity decreased over the time, the minimum appeared after 48 h and was 47.2% lower than initial (P<0.05); The SOD activity fluctuated, reached the minimum after 8 h, and the maximum activity was observed after 40 h which was 36% higher than the initial level (P<0.05); The CAT activity declined to the lowest level after 48 h and was 75.8% lower than initial (P<0.05). (5) The value of Fv/Fm of the 25℃ group dropped to the lowest after 48 h and was 56.8% lower than initial (P<0.05). Our results provide important information for the selection of heat-resistant S. japonica.