С4-фотосинтез. A metabolism of organic acids at family Crassulaceae plants (СAM-метаболизм)

you are: С4-фотосинтез

Sukkulenty growing in droughty areas, for example Cactus, Kalanchoe and Sedum, also fix atmospheric СО2 with formation of four-carbon connections. However on the physiological behaviour these plants differ from other representatives С4-типа. Ustitsa at them are opened at night and closed in the afternoon, usually the picture happens return: light stimulates opening ustits, and in the dark they remain closed. It is natural that water loss on evaporation through opened ustitsa at night much less, than in the afternoon, i.e. At the maximum temperature and the minimum relative humidity (see gl. 6) that is why such type of behaviour represents doubtless benefit for desert plants. These plants absorb at night atmospheric СО2, forming as a result of its fixing four-carbon organic acids, mainly the apple. role of a primary acceptor of carbon plays at them, as well as at other С4-растений, FEP (three-carbon connection). In the afternoon when the chlorophyll is activated by light, apple acid dekarboksiliruetsja with formation of three-carbon connection and СО2 of which then and are under construction sugar six-carbon th in Calvin's cycle - Bensona. From three-carbon connection it is recycled fosfoenolpiruvat which can act again now in a role of acceptor СО2. Similar behaviour, i.e. Alternation throughout days of two processes - accumulation of acids (at night) and their disintegration in afternoon), has received the name ITSELF, on family Crassulaceae to which many from such sukkulentov belong and in which this phenomenon has been found out for the first time. At ITSELF primary karboksilirovanie and formation of six-carbon Sugars proceed in the same cages, but at various times whereas at other С4-растений these processes occur simultaneously, but can be dated for different cages. The Fig. 4.21 illustrates these parities.

Photosynthesis End-products, geksozofosfaty, are translated in starch for storage and in sucrose for transportation, in other parts of a plant; besides, they turn in the course of breath to the various building blocks necessary for a plant. We will consider all these processes in the following chapter.