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Compartmentation and flux analysis of Ca~(2+) in citrus root

Xiao Langtao, Hu Dujing

Department of Basic Sciences,Hunan Agricultural University.Changsha 410128,Hunan

Abstract

The compartmental analysis method for Ca~(2+) was improved according to the high Ca~(2+) content in free space and its reuse ability in citrus (Citrus unshiu Marc.) root, The results showed a high efflux rate and a low influx rate of citrus root for Ca~(2+) uptake. The unidirectional rate constant of Ca~(2+) from cytoplasm to environment (K_(co)) was much higher than that (K_(oc)) was much higher than that (K_(oc)) in the opposite direction(table 2). Most of the Ca~(2+) enter the cytoplasm soon return to the envitonment. It was found that the distribution of Ca~(2+) in citrus root is in the following order: free space (33.135#mu#mol/L)>vacuole(20.157 #mu#mol/L)>cytoplasm (1.029 #mu#mol/L) (table 1). The net influx (J_(oc) of Ca~(2+) into the citrus root was very low (0.097 #mu#mol g~(-1) FW h~(-1)). The upward transport rate was even lower (0.015 #mu#mol g~(-1) FW h~(-1)), which was only 15.46% of the influx, indicating that only a tiny amount of the Ca~(2+) absorbed by the root was transported to the upper parts of the plant.

Key words: Citrus;Calcium;Uptake;Transport;Fluxanalysis

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Citing This Article：

Xiao Langtao, Hu Dujing. Compartmentation and flux analysis of Ca~(2+) in citrus root. Acta Physiol Sin 1997; 49 (3): (in Chinese with English abstract).