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Plant Physiology 44:255-261 (1969) © 1969 American Society of Plant Biologists Absorption of Copper, Zinc, and Manganese by Sugarcane Leaf Tissue 1a Plant Physiology Department, Hawaii Agricultural Experiment Station, University of Hawaii, Hilo, Hawaii 96720
The absorption of Cu2+, Zn2+, and Mn2+ by leaf tissue of 4-month old sugarcane plants (Saccharum officinarum L., var. H53-263) has been investigated. After the "apparent free space" fraction was desorbed, the absorption of Cu2+, Mn2+, and Zn2+ yielded a curve typical of many ion uptake processes when measured as a function of the external concentration. However, only 1 absorption mechanism was evident for each cation. The pH optimum for Cu2+ and Zn2+ uptake was 5.0 to 6.0, whereas that for Mn2+ absorption was 4.5 to 6.0. Absorption was competitively inhibited by H+, and this inhibition was reversible when 0.5 mM Ca2+ was present. Cu2+ and Zn2+ were absorbed through the same carrier sites, as concluded from their mutually competitive activities. Mn2+ was absorbed through a second, independent mechanism. Uptake of each cation was strongly inhibited by uncouplers of oxidative phosphorylation, by Amytal and Nembutal2, by 5 x 102M succinate, and by ADP and Pi. Absorption of Cu2+, Zn2+, and Mn2+ was concluded to be coupled to oxidative phosphorylation, and specifically to energy-conservation Site I.
1 Journal Series No. 1026 of the Hawaii Agricultural Experiment Station. This article has been cited by other articles:
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