Photooxidation Tolerance Characters of a New Purple Pepper

Huai Zi (HZ) is a new purple mutant of green pepper (PI 631133) that is obtained from the United States Department of Agriculture. The net photosynthetic rate (P-N), chlorophyll fluorescence parameters, antioxidant substances, antioxidant enzymes, photosystem 1 (PS1) and PS2 activities were studied through methyl viologen (MV) treatment. The results showed that the P-N, actual photochemical efficiency of PS2 (Phi PS2), photochemical quenching coefficient (q(P)), PS1 and PS2 activities in HZ were lower than those in green pepper. HZ had a stronger ability to eliminate reactive oxygen species(O-2(center dot-)) and accumulated less malondialdehyde (MDA) (a membrane lipid peroxidation product) than did green pepper, and had a higher content of antioxidants and antioxidant enzyme activity. This suggests that the lower light energy absorption and higher thermal dissipation and antioxidant activity of HZ contributed to a more stable PS2 photosynthetic capacity, which resulted in photooxidation tolerance. Hence, our study strongly suggests that pepper hybrids can achieve a modest ratio of chlorophyll and anthocyanin content, high P-N and resistance to photooxidation, improving yield and resistance to adverse environments.