Global warming has increased the frequency and duration of high temperature (HT) stress. Photosynthesis determines yield in maize and is extremely HT sensitive. The effects of HT on photosynthesis in maize leaves have been strongly examined under controlled conditions. Here, to explore the mechanism and primary inhibitory sites of HT to photosynthesis, the HT sensitivity of photosynthesis in XY335 and ZD958 maize hybrids was systematically studied in field by multiple methods. HT decreased leaf area and photosynthetic rate of unit leaf area and hence limited growth. HT disrupted chloroplast and mitochondrial membrane structure, possibly delaying photosynthetic recovery after HT. These changes were greater in XY335 than ZD958. Stomatal conductance decreased significantly under HT, and this did not restrict CO₂ fixation but may weaken the heat dissipation through transpiration. HT caused photoinhibition of PSII but not PSI. HT damaged both the oxygen‐evolving complex, located at donor side of PSII, and electron transfer from Q_A to Q_B, located at acceptor side of PSII. Interference of electron transfer from Q_A to Q_B caused by degradation of Q_B‐binding (D1) protein was the primary site of PSII inhibition by HT in maize leaves. The different stomatal behaviour and photoinhibition sites under HT between maize and wheat were discussed.

中文翻译：

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高温通过破坏叶绿体超微结构和光系统II减少玉米叶片的光合作用

全球变暖增加了高温（HT）压力的频率和持续时间。光合作用决定了玉米的产量，并且对HT非常敏感。在受控条件下，强烈检查了HT对玉米叶片光合作用的影响。在此，为探索HT对光合作用的机理和主要抑制位点，通过多种方法在田间系统研究了XY335和ZD958玉米杂交种对HT光合作用的敏感性。HT减少了叶面积和单位叶面积的光合速率，因此限制了生长。HT破坏叶绿体和线粒体膜结构，可能延迟HT后的光合恢复。XY335中的这些变化大于ZD958。在高温条件下气孔导度显着下降，这并不限制CO ₂固定，但可能通过蒸腾作用减弱散热。HT引起PSII的光抑制，而不引起PSI。HT破坏了位于PSII供体侧的析氧复合物和位于PSII受体侧的Q _A到Q _B的电子转移。Q _B结合（D1）蛋白降解引起的从Q _A到Q _B的电子转移干扰是HT在玉米叶片中抑制PSII的主要部位。讨论了玉米和小麦在高温条件下不同的气孔行为和光抑制位点。