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 (ΦPS2), photochemical quenching coefficient (qP), PS1 and PS2 activities in HZ were lower than those in green pepper. HZ had a stronger ability to eliminate reactive oxygen species(O2 (•-)) 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.