| Bangia fuscopurpurea, with its high nutritional value, is a characteristic cultivated seaweed species in China. Against the backdrop of current climate change, investigating the response of B. fuscopurpurea to different temperatures, particularly high temperatures, is significant for guiding the breeding of heat-tolerant varieties and promoting the sustainable and healthy development of the industry. This study elucidates the photosynthetic and antioxidative physiological responses of B. fuscopurpurea to different temperatures (5, 10, 15, 20, and 25°C) by examining parameters such as the maximum fluorescence yield of photosystem II (Fv/Fm), maximum relative electron transport rate (rETRmax), malondialdehyde (MDA) content, soluble protein (SP) content, superoxide dismutase (SOD) activity, catalase (CAT) activity, ascorbate peroxidase (APX) activity, and glutathione reductase (GR) activity. The results reveal that: (1) Overall, Fv/Fm and rETRmax of B. fuscopurpurea exhibit a trend of initially increasing and then decreasing with temperature elevation. Throughout the cultivation period, B. fuscopurpurea maintained relatively high levels of Fv/Fm and rETRmax at 15°C; however, within the first 3 days, Fv/Fm and rETRmax values at 20°C and 25°C were significantly lower compared to other temperature groups, but by day 5, they rose to levels comparable to those of the 15-20°C group, significantly higher than those of the 5-10°C group. (2) The MDA content initially decreased and then increased with temperature elevation, with the MDA content at 15°C significantly lower than that of other groups. Early on (6h), MDA content was higher at low temperatures (5-10°C), but with prolonged treatment time (5 days), MDA content significantly increased in the high-temperature groups (20-25°C). (3) The SP content was highest at 15-20°C, with no significant difference between the high temperature (25°C) and low temperature (5-10°C) groups. (4) SOD, APX, GR, and CAT activities were generally higher at low and high temperatures, particularly on day 5, significantly higher than those of the 15-20°C group. With prolonged cultivation time (5 days), GR activity significantly increased in the 25°C and 10°C groups, while CAT activity significantly increased in the 5-10°C group. These results suggest that 15°C is more suitable for the growth of B. fuscopurpurea, but it also exhibits strong adaptability to high temperatures (20-25°C). During temperature stress acclimationadaptation, antioxidative enzymes play a positive role. |
