本文關(guān)鍵詞： 水生植物 C4途徑 CAM 碳濃縮機(jī)制 光合作用 淀粉　出處：《中國科學(xué)院武漢植物園》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：沉水植物龍舌草的光合代謝具有三種無機(jī)碳濃縮機(jī)制:組成型C4途徑,對HCO3-的利用以及在低CO2條件下兼性景天酸代謝途徑(CAM)。關(guān)于這三種碳濃縮機(jī)制之間的調(diào)控以及在不同時間尺度,不同光照和CO2條件下的相互作用還不明確。本文利用Gran滴定、CAM指標(biāo)、光合關(guān)鍵酶活性的測定等方法檢測了光照和CO2長期馴化調(diào)節(jié)、短期高碳響應(yīng)以及短期低光處理后葉片的生理變化。研究發(fā)現(xiàn):無論高、低CO2條件下,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,表明龍舌草運行C4途徑。高光、低C02處理下龍舌草的晝夜酸度差可高達(dá)17-25 μequivg-1 FW,而高CO2處理后的龍舌草無顯著的晝夜酸度差,表明低CO2處理后龍舌草被誘導(dǎo)出CAM途徑。在長期馴化和短期暴露實驗中,即使在暗周期結(jié)束時PEPC和磷酸丙酮酸雙激酶(PPDK)的活性仍然很高,這保證了夜間蘋果酸的持續(xù)累積以及白天的碳固定。龍舌草在光周期開始時即以2-3 μequiv g-1 FW h-1的速率進(jìn)行脫羧反應(yīng),且高光下的脫羧速率顯著高于低光條件;而經(jīng)過高碳的短期暴露(晝夜),其在白天仍進(jìn)行正常的脫羧反應(yīng),表明龍舌草白天脫羧時不受外界高CO2濃度的影響。白天隨著蘋果酸脫羧,酸度減少,淀粉含量增加。通過計算龍舌草CAM途徑固定濃縮的CO2對光合作用的貢獻(xiàn),比率可達(dá)21%;而夜間蘋果酸的合成所捕獲的CO2僅占呼吸釋放CO2的6%。結(jié)合葉片超微結(jié)構(gòu)的觀察,光照和CO2影響葉綠體和線粒體的形態(tài)、數(shù)目以及分布。以上結(jié)果表明,龍舌草碳濃縮機(jī)制對外界光、CO2的變化呈現(xiàn)出不同的響應(yīng)特征.,無論高、低碳環(huán)境,龍舌草都能運行C4途徑;低碳下CAM途徑可被誘導(dǎo)產(chǎn)生,并且白天蘋果酸的脫羧速率受光照強(qiáng)度調(diào)節(jié),夜間酸度的累積受環(huán)境中CO2濃度調(diào)節(jié)。龍舌草是目前唯一發(fā)現(xiàn)的CAM和C4同時存在于同一組織中以及僅有的兩個具有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-.
【學(xué)位授予單位】：中國科學(xué)院武漢植物園
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S567.219

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