科研之友
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摘要
The C-4 plants, whose first product of photosynthetic CO2 fixation is a four-carbon acid, have evolved independently many times. Crassulacean acid metabolism (CAM) is a biological mechanism known to exhibit some C-4 characteristics such as the C-3 cycle during daylight and demonstrates the C-4 cycle at night. There are also various C-3-CAM intermediates, whose CAM pathway can be induced by environmental changes. However, neither fungus-induced CAM nor Theaceae CAM have been reported previously. Here, we show that CAM could be generated by fungus infection in Camellia oleifera Abel. young leaves, even at a location of a single leaf where the upper part had been transformed into a succulent one, while the lower part remained unchanged. The early photosynthetic products of dark-grown C. oleifera succulent leaves were malate, whereas C. oleifera normal leaves and light-grown succulent leaves incorporated most of C-14 into the primary photosynthetic product 3-phosphoglycerate. Camellia oleifera succulent leaves have a lower absolute delta C-13 value, much lower photorespiration rates and lower transpiration rates during the day than those of C. oleifera normal leaves. Like a typical CAM plant, stomata of C. oleifera succulent leaves closed during the daylight, but opened at night, and therefore had a detectable CO2 compensation point in darkness. Net photosynthetic rates (P-n) fluctuated diurnally and similarly with stomatal aperture. No light intensity saturation could be defined for C. oleifera succulent leaves. C-4 key enzymes in C. oleifera succulent leaves were increased at both the transcriptional/translational levels as well as at the enzyme activity level.
- 出版日期2012-2
- 单位成都大学; 四川农业大学; 绵阳师范学院
