Hideg Eva, Kós Péter B, Schreiber Ulrich
Institute of Plant Biology, Biological Research Center, Szeged, 6701 Hungary.
Plant Cell Physiol. 2008 Dec;49(12):1879-86. doi: 10.1093/pcp/pcn170. Epub 2008 Nov 5.
Non-photochemical chlorophyll fluorescence quenching (NPQ) plays a major role in the protection of the photosynthetic apparatus against damage by excess light, which is closely linked to the production of reactive oxygen species (ROS). The effect of a short heat treatment on NPQ and ROS production was studied with detached tobacco leaves by fluorescence imaging of chlorophyll and of the ROS sensor dye HO-1889NH. NPQ was stimulated >3-fold by 3 min pre-treatment at 44 degrees C, in parallel with suppression of CO(2) uptake, while no ROS formation could be detected. In contrast, after 3 min pre-treatment at 46 degrees C, NPQ was suppressed and ROS formation was indicated by quenching of HO-1889NH fluorescence. After 3 min pre-treatment at 46 degrees C and above, partial inactivation of ascorbate peroxidase and light-driven accumulation of H(2)O(2) was also observed. These data are discussed as evidence for a decisive role of the Mehler ascorbate peroxidase or water-water cycle in the formation of the NPQ that reflects down-regulation of PSII.
非光化学叶绿素荧光猝灭（NPQ）在保护光合机构免受过量光照损害方面起着主要作用，而过量光照与活性氧（ROS）的产生密切相关。通过叶绿素荧光成像和ROS传感器染料HO-1889NH，利用离体烟草叶片研究了短期热处理对NPQ和ROS产生的影响。在44℃预处理3分钟可使NPQ增加3倍以上，同时抑制CO₂吸收，且未检测到ROS形成。相反，在46℃预处理3分钟后，NPQ受到抑制，HO-1889NH荧光猝灭表明有ROS形成。在46℃及以上预处理3分钟后，还观察到抗坏血酸过氧化物酶部分失活以及H₂O₂的光驱动积累。这些数据被作为梅勒抗坏血酸过氧化物酶或水-水循环在反映PSII下调的NPQ形成中起决定性作用的证据进行了讨论。
