Changes in photosynthetic activities were studied with tobacco (Nicotiana tabacum L.) leaves and chloroplasts infected by cucumber mosaic virus (CMV) at the top, middle and bottom located leaves. Net photosynthetic rate was reduced at all three positioned leaves, with the maximum reduction occurring at the top leaves (31.9% of control). The infected chloroplasts showed a reduction in electron transport rates of the whole chain electron transport, photosystem Ⅱ (PSⅡ) and photosystem Ⅰ (PSⅠ). Since the decline in the whole chain electron transport (15.6% of control, H2O→MV) closely paralleled the decline in PSⅡ activity (20.9% of control, H2O→PBQ), the inhibition of the latter was probably responsible for the overall decrease. Chlorophyll a fluorescence measurements showed a variable reduced fluorescence yield (Fv/Fo) which indicated that PSⅡ was impaired and the CO2 assimilation was disturbed by CMV infection. Fluorescence emission spectra at 77 K indicated that energy distribution between PSⅡ and PSⅠ was affected. F686/F734 of infected leaves and chloroplasts increased and the greatest increase (331.1% of control ) was found in the top leaves. These data may conclude that the infection inhibited mainly the PSⅡ activity.
黄瓜花叶病毒对烟草叶片和叶绿体光合活性的影响
王春梅1,4 施定基1* 朱水芳2 田波3 魏宁生4
（1. 中国科学院植物研究所光合作用研究中心，北京100093；2. 农业部植物检疫研究所，北京100029；
3. 中国科学院微生物研究所，北京100080；2. 西北农业大学植保系，陕西杨陵712100）
摘要：研究了烟草 (Nicotianatabacum L .)感染黄瓜花叶病毒后烟草植株不同部位 (顶层、中层、下层 )叶片的光合速率和叶绿体光化学反应的变化。感病的叶片净光合速率减少 ,顶层叶减少最多。病毒侵染抑制PSⅡ活性比PSⅠ活性更明显 ,特别是顶层叶。叶绿素a荧光测定表明还原态Q库减少 ,CO2 同化减少。从低温荧光发射光谱图变化中发现能量分配受干扰。
关键词： 黄瓜花叶病毒；烟草；光合活性；光系统II
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