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以‘保罗塔’番茄果实为试材,采用叶绿素成像荧光仪(MINI-IMAGING-PAM)和QE65000光谱议测试分析了热激胁迫对番茄果实表面光化学活性和叶绿素荧光光谱的影响。结果表明:在较低的热激胁迫下(36~43℃),最大光化学量子产量Fv/Fm稳中有降,反映温度胁迫引起PSⅡ功能的部分抑制,而此时调节性能量耗散量子产量Y(NPQ)的增加耗散了过剩光能,以减轻过剩光能对光合机构的进一步伤害;当温度超过43℃时,非调节性能量耗散的量子产量Y(NO)显著增加,Fv/Fm、PSⅡ天线转化效率Fv′/Fm′和电子传递ETR急剧下降,Y(NPQ)开始下降,表明PSⅡ反应中心的天线色素耗散机制可能遭到破坏,对高温胁迫的自我调节功能开始下降,PSⅡ反应中心已开始失活,光抑制程度加重;当温度超过果实表面PSⅡ蛋白复合体变性中点温度51.4℃时,激发能分配不平衡偏离系数(β/α–1)显著上升,叶绿素荧光衰减率Rfd急剧下降,反映此时激发能分配严重失衡,番茄潜在的CO2同化能力极弱。通过对标准状态变性自由能变△GD计算的变性中点温度Tm得出,Tm(Fv/Fm)大于Tm[Y(II)],说明PSⅡ的耐热性稍强于整个光合作用。
The effects of heat shock stress on the photochemical activity of the tomato fruits and the chlorophyll fluorescence spectra were analyzed using ’Paul Tower’ tomato fruits with MINI-IMAGING-PAM and QE65000 spectroscopy. The results showed that under the condition of low heat shock stress (36 ~ 43 ℃), the maximum photochemical quantum yield Fv / Fm decreased steadily, which reflected partial inhibition of PSⅡ function under temperature stress, while the regulatory energy dissipation quantum yield The increase of Y (NPQ) dissipates excess light energy to reduce the further damage to photosynthetic apparatus caused by excessive light energy. When the temperature exceeds 43 ℃, the quantum yield Y (NO) of unconditioned energy dissipation increases significantly, while Fv / Fm, PSII antenna conversion efficiency Fv ’/ Fm’ and electron transfer ETR dropped sharply, Y (NPQ) began to decline, indicating that the PSII reaction center of the antenna pigment dissipation mechanism may be destroyed, self-regulation of high temperature stress began to decline, PSⅡ reaction center started to deactivate and the degree of photoinhibition was aggravated. When the temperature exceeded the degeneration midpoint temperature of PSⅡ protein complex at fruit surface 51.4 ℃, the unbalanced excitation energy distribution coefficient (β / α-1) increased significantly, and chlorophyll fluorescence decay Rfd rate dropped sharply, reflecting a serious imbalance in the distribution of excitation energy, tomato potential CO2 assimilation is very weak. The Tm (Fv / Fm) is larger than Tm [Y (II)] through the denaturation of the midpoint temperature Tm calculated from the standard state of free energy change △ GD, indicating that PS Ⅱ heat resistance slightly stronger than the entire photosynthesis.