| Research Abstract |
Using 13 CAM species, optimum pH of phosphoenolpyruvate carboxylase(PEPC)and inter-species variation of malate sensitivities of PEPC were studied ; Optimum pH of PEPC showed significant intre-species difference among species. Especially Vanilla fragrant showed two optimum pHs of PEPC.This suggested the isozyme of PEPC in V.fragrant. Malate sensitivity of PEPC also showed difference in species. V.fragrant was grouped into the type of pinnata, which showed clear day/night change of the malate sensitivity. Sedum praealtum was classified to the type of ananas, which did not show the day/night change. Phalaenopsis, Opuntia vulgaris, Dendrobium ekapol, Hoya carnosa, Crassula argentea, Aloe thraskii, Porturacaria afra were grouped into the type of daigremontiana, which showed intermediate of above types.
Using three CAM plants, Anansu comosus, Kalanchoe daigremontiana, and K.pinnata, which showed different malate sensitivity of PEPC,located of PEPC in the cell and characteristics of isoelectric focusing were studied. The location of PEPC in the mesophyll cell was in different among three CAM plants. In K.pinnata, PEPC located mainly in cytosol and biomembrane. In A.comosus, PEPC distributed in the cytosol and on the surface of biomembrane. Most of PEPC of K.daigremontiana, more than 80%, existed in the biomembrane. Consequently, it was suggested that the difference of malate sensitivity in CAM species related to the inter-cellular location of PEPC.Isoelectric point of A.comosus, and K.pinnata and K.daigremonteana, was observed at 5.1 to 5.2, and 5.8 to 5.9, respectively.
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