Southern Federal University, Academy of Biology and Biotechnology, Rostov-on-Don, 344049, Russia.
Southern Federal University, Academy of Biology and Biotechnology, Rostov-on-Don, 344049, Russia.
Plant Physiol Biochem. 2024 Oct;215:109040. doi: 10.1016/j.plaphy.2024.109040. Epub 2024 Aug 13.
Adaptation and functional significance of chlorophyll deficit in the light green leaf sectors of variegated plants are little known. Efficiency of photosystem II for dark and light adapted states (F/F and ΔF/F') and fluorescence decrease rates (R) of light green leaf sectors of Dracaena fragrans L. were studied by methods of PAM-fluorometry and video registration. In addition, white light reflectance and transmittance of these leaf sectors were measured using an integrating sphere. Absorption was calculated from reflectance and transmittance. Net CO assimilation rates (P) were measured using a flow chamber and photolytic O evolution rates (PAYO) were studied by a novel method of Fourier photoacoustics which is insensitive to respiration, photorespiration and other processes of O uptake. All the photosynthetic parameters (F/F, ΔF/F', P and PAYO) were found to be very close between light green and normal green leaf sectors, whereas chlorophyll content and light absorption were 7.5-fold and 1.47-fold different respectively. Contradiction between low chlorophyll absorption and high (as in normal green sectors) rate of oxygenic photosynthesis in light-green sectors was proposed to be a consequence of different contribution of cyclic electron transport around PSII (CET-PSII) and/or around PSI (CET-PSI) in the total photosynthesis occurring in these sectors. Particularly, it cannot be excluded, that some part of CET activity occurring in normal green leaf sectors may be lost in the light green sectors retaining the same linear (non-cyclic) electron transport (LET) activity as in normal green sectors.
斑驳植物光绿叶片中叶绿素亏缺的适应和功能意义还知之甚少。本文采用 PAM 荧光仪和视频记录法研究了龙血树光绿叶片暗适应和光适应状态下的 PSII 效率（F/F 和 ΔF/F'）和荧光下降率（R），此外，还使用积分球测量了这些叶片光绿部分的白光反射率和透射率。根据反射率和透射率计算吸收率。采用流动室测量净 CO2 同化率（P），并采用傅里叶光声法研究了新型光解 O 释放率（PAYO），该方法对呼吸、光呼吸和其他 O 吸收过程不敏感。光绿和正常绿叶部分的所有光合参数（F/F、ΔF/F'、P 和 PAYO）都非常接近，而叶绿素含量和光吸收分别相差 7.5 倍和 1.47 倍。光绿部分的叶绿素吸收低而放氧光合作用速率高（与正常绿叶部分相同）之间的矛盾，被认为是 PSII 周围循环电子传递（CET-PSII）和/或 PSI 周围循环电子传递（CET-PSI）在这些部分发生的总光合作用中不同贡献的结果。特别是，不能排除在光绿部分发生的部分 CET 活性可能在保留与正常绿叶部分相同的线性（非循环）电子传递（LET）活性的情况下在光绿部分丢失。
