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Abstract

Cook, D.A., and C.M. Patterson. 2005 Sodium Chloride Induction of the Proton ATPase in Kosteletzkya virginca, the brackish marsh halophyte. JEMREST 2:09-18

The H⁺-ATPase of the plasma membrane regulates ion balance in the plant cell. As the major ion pump in plants, the H⁺-ATPase has an important role in excluding Na⁺ from the plant cell in all plants including halophytic species. Three cDNA fragments were amplified using an RT-PCR approach from K. virginica plants grown in one-half strength Hoaglunds’ solution amended with 171mM NaCl. Degenerate, nested, and gene specific primers were employed in the further amplification of these fragments into 1 complete (KVATP1) and 2 partial cDNA isoform clones (KVATP2, KVATP3). Sequence analysis confirmed that these three cDNA clones were homologous to plant proton ATPases. These three isoforms of the H⁺-ATPase are differentially expressed in different organs and over a time course of salinity treatment. Ribonuclease protection assays, using probes for 2 of the isoforms, confirmed these results. KVATP1 mRNA expression was detected in both roots and leaves after 30 min of NaCl treatment. Similarly in roots, KVATP2 mRNA increased as early as 15 min after NaCl treatment, which was elevated through 30 min, and declined to a lower level after 60 min. Based on these data, the H⁺-ATPase mRNA levels indicated that this enzyme has a role in the management of high levels of NaCl even in halophytic species.