Studies on the regulation properties of CAM type photosynthesis in pineapple

虽然在凤梨中观察到，夜间磷酸化磷酸烯醇丙酮酸（PEP）羧化酶对凤梨CAM型CO_2交换有一定的调节作用，但对CAM表达的贡献小于凤梨CAM。结果表明，苹果酸盐在扁桃体上积累的驱动力，如atp酶和pp酶，以及扁桃体的流动性对CAM的调节起着重要作用。此外，菠萝的磷酸果糖激酶（PFP）是由α和β亚基构建的，结果表明α亚基与其他植物的PFP调控相似。菠萝是一种典型的PEP羧激酶(PCK)-CAM植物，其线粒体外部NADH氧化与细胞色素途径的联系较多，与替代途径的联系较少。这种能力可能是菠萝在白天为细胞质PCK产生足量ATP的拟合机制之一。也就是说，PCK的CAM亚型与苹果酸酶（ME）的电子传递链与细胞色素氧化酶或替代氧化酶的连接是不同的。在夏季，凤梨CAM型光合作用的调节机制与凤梨CAM型光合作用的调节机制不同，尽管凤梨和凤梨的CAM型光合作用也有一些相似的特性。其次，糖酵解和线粒体等不同代谢和器官的交叉对话是CAM调控的重要课题。

Although CAM type CO_2 exchange in pineapple was partially regulated by the phosphorylation of phosphoenolpyruvate (PEP) carboxylase in night as observing in Kalanchoe CAM, the contribution to the CAM expression was less than the Kalanchoe CAM. It was appeared that the driving force of the malate accumulation on the tonoplast, such as ATPase and PPase, and the tonplast ligidity contributed to the CAM regulation. In addition, phosphofructokinase (PFP) of pineapple was constructed by subunits of α and β, the result showed that α subunit concerned to the PFP regulation as similar to other plant species. External NADH oxidation in mitochondria of pineapple, a typical PEP carboxykinase (PCK)-CAM plant, was more connected with the cytochrome pathway and less with the alternative pathway. This capacity might be one of the fitting mechanisms of pineapple to produce a sufficient amount of ATP for cytosolic PCK in the daytime. That is, it was suggested that the connection of electron transfer chain to cytochrome oxydase or alternative oxydase is different between the CAM subtypes of PCK and malic enzyme (ME). In summery, pineapple CAM type photosynthesis has a different regulation mechanism to the authentic CAM regulation observed in Kalanchoe specied, although some similar properties also contributed to both CAM regulations of pineapple and Kalanchoe. In the next, cross-talks of different metabolism and organs, such as glycolysis and mitochondria are important topics in the CAM regulation.