水稻叶片光氧化研究进展

探讨超级粳稻品种南粳44和南粳5055对光氧化处理的光化学响应特性及其耐性机制，比较耐光氧化特性的差异，为优质超级稻的培育提供理论参考。

选用南粳44和南粳5055为试材，在抽穗10 d后取剑叶进行7 d光氧化处理，对2个粳稻品种处理前后剑叶的叶绿素荧光动力学参数进行比较和分析。

光氧化处理前，南粳44和南粳5055的叶绿素荧光动力学参数均无显著差异；光氧化处理后，2个品种的光系统Ⅱ (PSⅡ) 均受到不同程度的光抑制，PSⅡ结构和生理状态受损，光合性能下降，初始荧光(F_o)增加，最大光化学效率(F_v/F_m)和叶片光合性能指数(PI_abs)下降，PSⅡ光化学活性降低，但南粳44的光化学活性显著高于南粳5055。光氧化处理后，南粳44的单位反应中心吸收(ABS/RC)、捕获(TR_o/RC)和耗散(DI_o/RC)的能量与对照相比未显著升高，但显著低于南粳5055，说明南粳44单位面积有活性反应中心数量较高，其剑叶PSⅡ供体侧参数K相相对可变荧光(V_K)和L相相对可变荧光(V_L)分别是南粳5055的0.50倍和0.45倍，PSⅡ受体侧参数J点相对可变荧光(V_J)和I点相对可变荧光(V_I)及Q_A被还原的程度(M_o)和受体侧库的大小(S_m)分别为南粳5055的0.60倍、0.91倍、0.50倍和1.74倍，其剑叶PSⅡ供体侧电子的供应能力和受体侧Q_A向Q_B电子传递能力显著优于南粳5055；南粳44的F_v/F_m和PI_abs较南粳5055分别显著高28.24%和776.82%。

南粳44 PSⅡ的光合性能较强，可通过自身调节降低光抑制，其耐光氧化特性优于南粳5055。

Metabolic reprogramming in chloroplasts under heat stress in plants

To investigate the photochemical response characteristics of super japonica rice varieties Nanjing44 and Nanjing5055 to photooxidation treatment and their tolerance mechanism, and to compare the differences in photooxidation resistance characteristics, providing theoretical reference for the cultivation of high quality super rice. Nanjing44 and Nanjing5055 were used as test materials. After 10 days of flowering, the leaves were photooxidized for seven days to analyze and compare the chlorophyll fluorescence kinetic parameters of two japonica rice varieties before and after treatment. There was no significant difference in chlorophyll fluorescence kinetic parameters between Nanjing44 and Nanjing5055 before photooxidation treatment. After photooxidation treatment, the photosystem Ⅱ (PSⅡ) of the two cultivars were suppressed to varying degrees, the structure and physiological state of PSⅡ were damaged, the photosynthetic performance of PSⅡ was decreased, the initial fluorescence (F_o) was increased, the maximum photochemical efficiency (F_v/F_m) and leaf photosynthetic performance index (PI_abs) were decreased, and the photochemical activity of PSⅡ was decreased. However, the photochemical activity of Nanjing44 was significantly higher than that of Nanjing5055. Absorption flux per RC (ABS/RC), trapped energy flux per RC (TR_o/RC) and dissipated energy flux per RC (DI_o/RC) of Nanjing44 were not significantly higher than those of the control after photooxidation treatment, but were significantly lower than those of Nanjing5055, indicating that the number of active reaction centers per unit area of Nanjing44 was relatively high. The donor side parameters relative variable fluorescence at 300 μs (V_K) and relative variable fluorescence at 150 μs (V_L) of Nanjing44 leaf PSⅡ were 0.50 times and 0.45 times of Nanjing5055, and the receptor side parameters relative variable fluorescence at 2 ms (V_J), relative variable fluorescence at 30 ms (V_I), approximated initial slope (in ms⁻¹) of the fluorescence transient (M_o) and size of PSⅡ receptor side library (S_m) ware 0.60 times, 0.91 times, 0.50 times and 1.74 times times of Nanjing5055, respectively. After photooxidation, the supply capacity of PSⅡ donor electron and the electron transfer capacity from Q_A to Q_B on the acceptor side of Nanjing44 were significantly better than that of Nanjing5055. The F_v/F_m and PI_abs of Nanjing44 were significantly higher than Nanjing5055 by 28.24% and 776.82%, respectively. Nanjing44 has better photooxidation resistance than Nanjing5055 due to its strong PSⅡ photosynthetic performance and reduced photoinhibition through self-regulation.