PSⅡ photochemistry and xanthophyll cycle during photoinhibition (exposed to strong light of 2 000 μmol photons·m -2 ·s -1 ) and the subsequent restoration were compared between two superhigh_yi...PSⅡ photochemistry and xanthophyll cycle during photoinhibition (exposed to strong light of 2 000 μmol photons·m -2 ·s -1 ) and the subsequent restoration were compared between two superhigh_yield rice hybrids (Liangyoupeijiu and Hua_an 3, the newly developed rice hybrids from two parental lines) and the traditional rice hybrid Shanyou 63 developed from three parental lines. The results showed that the maximal efficiency of PSⅡ photochemistry ( Fv/Fm ), the efficiency of excitation energy capture by open PSⅡ centers ( Fv′/Fm′ ), and the yield of PSⅡ electron transport ( Φ PSⅡ ) of the three rice hybrids decreased during photoinhibition. However, a greater decrease in Fv/Fm , Fv′/Fm′ , and Φ PSⅡ was observed in Shanyou 63 than in Liangyoupeijiu and Hua_an 3. At the same time, the components of xanthophyll cycle, antherxanthin (A) and zeathanxin (Z) increased rapidly while violaxanthin (V) decreased considerably. Both the rate of accumulation and the amount of A and Z in the two superhigh_yield rice hybrids were higher than that in Shanyou 63. The de_epoxidation state (DES) of xanthophyll cycle increased rapidly with the fast accumulation of A and Z, and reached the maximal level after first 30 min during photoinhibition. Of the three hybrids, the increasing rate of DES in Liangyoupeijiu and Hua_an 3 was higher than that in Shanyou 63. After photoinhibition treatment, the plant materials were transferred to a dim light (70 μmol photons·m -2 ·s -1 ) for restoration. During restoration, both chlorophyll fluorescence parameters and xanthophyll cycle relaxed gradually, but the rate and level of restoration in the two superhigh_yield rice hybrids were higher than those in Shanyou 63. Our results suggest that Liangyoupeijiu and Hua_an 3 had higher resistance to photoinhibition and higher capacity of non_radiative energy dissipation associated with xanthophyll cycle, as well as higher rate of restoration after photoinhibition, than Shanyou 63 when subjected to strong light.展开更多
文摘PSⅡ photochemistry and xanthophyll cycle during photoinhibition (exposed to strong light of 2 000 μmol photons·m -2 ·s -1 ) and the subsequent restoration were compared between two superhigh_yield rice hybrids (Liangyoupeijiu and Hua_an 3, the newly developed rice hybrids from two parental lines) and the traditional rice hybrid Shanyou 63 developed from three parental lines. The results showed that the maximal efficiency of PSⅡ photochemistry ( Fv/Fm ), the efficiency of excitation energy capture by open PSⅡ centers ( Fv′/Fm′ ), and the yield of PSⅡ electron transport ( Φ PSⅡ ) of the three rice hybrids decreased during photoinhibition. However, a greater decrease in Fv/Fm , Fv′/Fm′ , and Φ PSⅡ was observed in Shanyou 63 than in Liangyoupeijiu and Hua_an 3. At the same time, the components of xanthophyll cycle, antherxanthin (A) and zeathanxin (Z) increased rapidly while violaxanthin (V) decreased considerably. Both the rate of accumulation and the amount of A and Z in the two superhigh_yield rice hybrids were higher than that in Shanyou 63. The de_epoxidation state (DES) of xanthophyll cycle increased rapidly with the fast accumulation of A and Z, and reached the maximal level after first 30 min during photoinhibition. Of the three hybrids, the increasing rate of DES in Liangyoupeijiu and Hua_an 3 was higher than that in Shanyou 63. After photoinhibition treatment, the plant materials were transferred to a dim light (70 μmol photons·m -2 ·s -1 ) for restoration. During restoration, both chlorophyll fluorescence parameters and xanthophyll cycle relaxed gradually, but the rate and level of restoration in the two superhigh_yield rice hybrids were higher than those in Shanyou 63. Our results suggest that Liangyoupeijiu and Hua_an 3 had higher resistance to photoinhibition and higher capacity of non_radiative energy dissipation associated with xanthophyll cycle, as well as higher rate of restoration after photoinhibition, than Shanyou 63 when subjected to strong light.
