Abstract
Arabidopsis metal-tolerance protein 1 (AtMTP1) transports zinc into vacuole by Zn2+/H+ exchanger mechanism. AtMTP1 knockout mutant (mtp1) plants are sensitive to zinc at high concentrations, suggesting an essential role of AtMTP1 in zinc tolerance. In this study, we compared physiological and biochemical properties between the wild-type and mtp1 plants to elucidate mechanism of zinc toxicity and physiological role of AtMTP1 in zinc homeostasis. In 0.5 mM Zn2+, roots growth of mtp1 was reversibly inhibited. It may not be due to necrosis of cells. Cell division and elongation were critically suppressed in roots under zinc stress and reactive oxygen species (ROS) were generated in the meristematic zone. ROS may be one of the key factors of zinc toxicity or stress signaling. We will also discuss about the characteristic differences of gene expression, ion valance and cell morphology between wild-type and mtp1 plants under the zinc stress.
