6533b871fe1ef96bd12d0dd0

RESEARCH PRODUCT

Calcium- and potassium-permeable plasma membrane transporters are activated by copper inArabidopsisroot tips: linking copper transport with cytosolic hydroxyl radical production

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description

Transition metals such as copper can interact with ascorbate or hydrogen peroxide to form highly reactive hydroxyl radicals (OH . ), with numerous implications to membrane transport activity and cell metabolism. So far, such interaction was described for extracellular (apoplastic) space but not cytosol. Here, a range of advanced electrophysiological and imaging techniques were applied to Arabidopsis thaliana plants differing in their copper-transport activity: Col-0, high-affinity copper transporter COPT1-overexpressing (C1 OE ) seedlings, and T-DNA COPT1 insertion mutant ( copt1 ). Low Cu concentrations (10 μ m) stimulated a dose-dependent Gd 3+ and verapamil sensitive net Ca 2+ influx in the root apex but not in mature zone. C1 OE also showed a fivefold higher Cu-induced K + efflux at the root tip level compared with Col-0, and a reduction in basal peroxide accumulation at the root tip after copper exposure. Copper caused membrane disruptions of the root apex in C1 OE seedlings but not in copt 1 plants; this damage was prevented by pretreatment with Gd 3+ . Our results suggest that copper transport into cytosol in root apex results in hydroxyl radical generation at the cytosolic side, with a consequent regulation of plasma membrane OH . -sensitive Ca 2+ and K + transport systems.