Cetner M D, Kalaji H M, Goltsev V, Aleksandrov V, Kowalczyk K, Borucki W, Jajoo A
Department of Plant Physiology, Warsaw University of Life Sciences WULS-SGGW, 159 Nowoursynowska Street, 02-776 Warsaw, Poland.
Department of Plant Physiology, Warsaw University of Life Sciences WULS-SGGW, 159 Nowoursynowska Street, 02-776 Warsaw, Poland.
Plant Physiol Biochem. 2017 Oct;119:81-92. doi: 10.1016/j.plaphy.2017.08.016. Epub 2017 Aug 24.
Nitrogen starvation has been stated to reduce chlorophyll a and accessory pigments, decrease photosynthetic efficiency, as well as modify chloroplast thylakoid membranes. However, the impact of N-deficiency on light-dependent reactions of photosynthesis has not been well understood. In this study, efficiency and structure of light-harvesting complex under N-deficiency conditions were investigated in two radish cultivars (Raphanus sativus var. sativus 'Fluo HF1' and 'Suntella F1'). Light-dependent reactions of photosynthesis were investigated by measuring in vivo chlorophyll a prompt fluorescence signal. Acquired data were utilised in two ways: by plotting fast induction curves and calculating OJIP-test biophysical parameters. Detailed analysis of difference curves as well as OJIP-test results showed that major disturbances were associated with photosystem II and its subunits, including decoupling of light-harvesting complexes, dysfunction of oxygen-evolving complex, and reaction centres inactivation. The maximum quantum yield of photosystem II primary photochemistry was severely restricted, causing an inhibition in electron transport through successive protein complexes in the thylakoid membrane. Structural changes were demonstrated by recording images using Transmission Electron Microscopy (TEM). TEM investigations showed intensive starch accumulation under N-deficiency. Rare thylakoid stacks distributed in tiny layers of stroma around grains and chloroplast periphery were observed in cells of N-deficient plants. The application of principal component analysis (PCA) on OJIP-test results allowed characterizing the dynamics of stress response and separating parameters according to their influence on plants stress response. 'Suntella F1' genotype was found to be more sensitive to nitrogen deficiency as compared to 'Fluo HF1' genotype.
据报道，氮饥饿会减少叶绿素a和辅助色素，降低光合效率，并改变叶绿体类囊体膜。然而，氮缺乏对光合作用光反应的影响尚未得到充分了解。在本研究中，研究了两个萝卜品种（萝卜‘Fluo HF1’和‘Suntella F1’）在缺氮条件下光捕获复合体的效率和结构。通过测量体内叶绿素a快速荧光信号来研究光合作用的光反应。获得的数据以两种方式使用：绘制快速诱导曲线和计算OJIP测试生物物理参数。对差异曲线以及OJIP测试结果的详细分析表明，主要干扰与光系统II及其亚基有关，包括光捕获复合体的解偶联、放氧复合体的功能障碍以及反应中心失活。光系统II原初光化学的最大量子产率受到严重限制，导致通过类囊体膜中连续蛋白质复合体的电子传递受到抑制。通过透射电子显微镜（TEM）记录图像来证明结构变化。TEM研究表明缺氮条件下淀粉大量积累。在缺氮植物的细胞中，观察到稀有的类囊体堆叠分布在围绕颗粒和叶绿体周边的微小基质层中。对OJIP测试结果应用主成分分析（PCA）可以表征应激反应的动态，并根据参数对植物应激反应的影响对其进行分离。发现‘Suntella F1’基因型比‘Fluo HF1’基因型对氮缺乏更敏感。
