Specific increase in phosphatase isozymes in cucumber cucumis sativus cultivar seiri ki no. 2 roots caused by calcium deficiency

Yamaya, T.; Tanigawa, M.; Matsumoto, H.

Plant and Cell Physiology 23(3): 385-396


ISSN/ISBN: 0032-0781
Accession: 006456905

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Phosphatases in cucumber roots, whose production was induced by Ca2+ deficiency, were characterized chromatographically using ATP, 2'(3')-AMP and p-nitrophenylphosphate (PNPP) as substrates. Ca2+ deficiency stimulated > 10-fold increases in the activities with these substrates of the nonadsorbed fraction from a DEAE-cellulose column. Several fractions associated with these phosphatase activities were eluted from the column with NaCl solution; their levels increased less with Ca2+ starvation. When the non-adsorbed fraction from Ca2+-starved roots was applied to a Sephadex G-200 column, fractions associated with 2'(3')-AMPase (phosphatase I) and with ATPase and PNPPase (phosphatase II) were separated. In the control roots, very weak activities of phosphatases I and II occurred at the same position on the gel filtration. The phosphatase I isolated from the control and Ca2+-starved roots was extremely specific to nucleoside 2'(3')-monophosphates, whereas phosphatase II from both types of roots had a relatively broad substrate specificity. When phosphatase I from Ca2+-starved roots was stained with 2'(3')-AMP in CaCl2 after polyacrylamide gel electrophoresis, a single band was obtained. Phosphatase I from control roots showed a single band with the same Rf value. Phosphatase II from both types of roots contained 2 isozyme bands when the activities were stained with either ATP or PNPP. Evidently Ca2+ starvation causes specific increases in the level of phosphatases I and II in cucumber roots.