光照和无机碳对龙舌草光合碳浓缩机制的影响

发布时间：2018-02-07 14:09

本文关键词： 水生植物 C4途径 CAM 碳浓缩机制光合作用淀粉　出处：《中国科学院武汉植物园》2017年硕士论文　论文类型：学位论文

【摘要】：沉水植物龙舌草的光合代谢具有三种无机碳浓缩机制:组成型C4途径,对HCO3-的利用以及在低CO2条件下兼性景天酸代谢途径(CAM)。关于这三种碳浓缩机制之间的调控以及在不同时间尺度,不同光照和CO2条件下的相互作用还不明确。本文利用Gran滴定、CAM指标、光合关键酶活性的测定等方法检测了光照和CO2长期驯化调节、短期高碳响应以及短期低光处理后叶片的生理变化。研究发现:无论高、低CO2条件下,磷酸烯醇式丙酮酸羧化酶(PEPC)和1-5-二磷酸核酮糖羧化酶(Rubisco)的比值5,表明龙舌草运行C4途径。高光、低C02处理下龙舌草的昼夜酸度差可高达17-25 μequivg-1 FW,而高CO2处理后的龙舌草无显著的昼夜酸度差,表明低CO2处理后龙舌草被诱导出CAM途径。在长期驯化和短期暴露实验中,即使在暗周期结束时PEPC和磷酸丙酮酸双激酶(PPDK)的活性仍然很高,这保证了夜间苹果酸的持续累积以及白天的碳固定。龙舌草在光周期开始时即以2-3 μequiv g-1 FW h-1的速率进行脱羧反应,且高光下的脱羧速率显著高于低光条件;而经过高碳的短期暴露(昼夜),其在白天仍进行正常的脱羧反应,表明龙舌草白天脱羧时不受外界高CO2浓度的影响。白天随着苹果酸脱羧,酸度减少,淀粉含量增加。通过计算龙舌草CAM途径固定浓缩的CO2对光合作用的贡献,比率可达21%;而夜间苹果酸的合成所捕获的CO2仅占呼吸释放CO2的6%。结合叶片超微结构的观察,光照和CO2影响叶绿体和线粒体的形态、数目以及分布。以上结果表明,龙舌草碳浓缩机制对外界光、CO2的变化呈现出不同的响应特征.,无论高、低碳环境,龙舌草都能运行C4途径;低碳下CAM途径可被诱导产生,并且白天苹果酸的脱羧速率受光照强度调节,夜间酸度的累积受环境中CO2浓度调节。龙舌草是目前唯一发现的CAM和C4同时存在于同一组织中以及仅有的两个具有CAM和利用HCO3-的水生植物之一。
[Abstract]:The photosynthetic metabolism of the submerged plant tequila has three inorganic carbon concentration mechanisms: the compositional C4 pathway. The utilization of HCO3- and the metabolic pathway of facultative cloveric acid at low CO2. Regulation between the three mechanisms of carbon concentration and at different time scales, The interaction under different illumination and CO2 conditions is not clear. In this paper, the long-term acclimation regulation of light and CO2 was detected by means of Gran titration and the determination of photosynthetic key enzyme activity. The physiological changes of leaves after short term high carbon response and short term low light treatment. The ratio of phosphoenolpyruvate carboxylase (PEPC) and 1-5-diphosphate ribonucleose carboxylase (Rubiscoc) is 5, which indicates that tequila has a C4 pathway. Under low CO2 treatment, the diurnal acidity difference of tequila was as high as 17-25 渭 equivg-1 FW, while that of high CO2 treatment had no significant diurnal acidity difference, indicating that tequila was induced into CAM pathway after low CO2 treatment. Even at the end of dark cycle, the activity of PEPC and phosphopyruvate dikinase PPDK was very high, At the beginning of photoperiod, the decarboxylation reaction was carried out at the rate of 2-3 渭 equiv g ~ (-1) FW ~ (-1), and the decarboxylation rate at high light was significantly higher than that under low light. However, after short-term exposure to high carbon (diurnal and diurnal), normal decarboxylation reaction was carried out in the daytime, which indicated that the decarboxylation of tequila was not affected by high CO2 concentration in daytime, and the acidity decreased with the decarboxylation of malic acid in the daytime. The ratio of fixed concentrated CO2 to photosynthesis was 21 by calculating the contribution of CO2 to photosynthesis by CAM pathway, while the CO2 captured by nocturnal malic acid synthesis accounted for only 6% of respiratory release CO2. Light and CO2 affect the morphology, number and distribution of chloroplasts and mitochondria. The CAM pathway can be induced under low carbon, and the decarboxylation rate of malic acid during the day is regulated by light intensity. The accumulation of nocturnal acidity is regulated by the concentration of CO2 in the environment. Tequila is one of the only CAM and C4 found in the same tissue and only two aquatic plants with CAM and HCO3-.
【学位授予单位】：中国科学院武汉植物园
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S567.219

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