Abstract
Plants respond to abiotic stresses by altering the transport activity of various metabolites and ions. Microarray analyses identified various osmotic-stress inducible genes for membrane-proteins including a potassium transporter, KUP6, in Arabidopsis. Expression of KUP6 was induced by mannitol and drought treatments in plants. The GUS activity was detected in root tips and vascular cells, and increased in young seedling roots by mannitol and salt treatments of the transgenic plants expressing the KUP6 promoter-GUS gene. The KUP6-GFP protein was localized to the plasma membrane in root tips of the transgenic Arabidopsis. A T-DNA insertion mutant of KUP6 showed enlarged leaf sizes under normal growth condition. The root growth of kup6 showed decreased ABA sensitivity and increased auxin sensitivity compared with that of wild-type plants. Furthermore, drought stress tolerance of kup6 was decreased significantly. These results suggest that KUP6 plays an important role in drought stress tolerance in Arabidopsis.
