Proton Pumping in Growing Part of Maize Root: Its Correlation with 14-3-3 Protein Content and Changes in Response to Osmotic Stress

A. V. Shanko¹, M. M. Mesenko², O. I. Klychnikov¹, A. V. Nosov^2*, and V. B. Ivanov²

¹Institute of Agricultural Biotechnology, Russian Academy of Agricultural Sciences, ul. Timiryazevskaya 42, Moscow 127550, Russia; fax: (7-095) 977-0947; E-mail: shanko@iab.ac.ru

²Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, ul. Botanicheskaya 35, Moscow 127276, Russia; fax: (7-095) 977-8018; E-mail: avn@ippras.ru

^* To whom correspondence should be addressed.

Received January 4, 2003; Revision received March 12, 2003

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The spatial pattern of mitotic activity, cell elongation, rate of H⁺ fluxes, and 14-3-3 protein content were determined in Zea mays roots. We found that the regions along the apical part of the growing root conversely differ in their proton pumping activity. Higher rate of H⁺ efflux coincides with higher growth rate and correlates with increased 14-3-3 protein content in membrane preparations. The segment consisting of the root cap and the apical part of the meristem exerts net inward proton pumping, which can be inverted under fusicoccin treatment or osmotic stress. In the latter case, this inversion is accompanied by accumulation of 14-3-3 protein in plasma membranes. The results obtained highlight 14-3-3 protein as an obvious candidate for the fine regulation of plasma membrane H⁺-ATPase in root apex.

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KEY WORDS: Zea mays, root, elongation growth, plasma membrane H⁺-ATPase, 14-3-3 protein, osmotic stress

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