title: Overexpression of the rice AKT1 potassium channel affects potassium nutrition and rice drought tolerance.
abstract: Potassium (K(+)) is the most important cationic nutrient for all living organisms and has roles in most aspects of plant physiology. To assess the impact of one of the main K(+) uptake components, the K(+) inward rectifying channel AKT1, we characterized both loss of function and overexpression of OsAKT1 in rice. In many conditions, AKT1 expression correlated with K(+) uptake and tissue K(+) levels. No salinity-related growth phenotype was observed for either loss or gain of function mutants. However, a correlation between AKT1 expression and root Na(+) when the external Na/K ratio was high suggests that there may be a role for AKT1 in Na(+) uptake in such conditions. In contrast to findings with Arabidopsis thaliana, we did not detect any change in growth of AKT1 loss of function mutants in the presence of NH4 (+) Nevertheless, NH4 (+)-dependent inhibition was detected during K(+) uptake assays in loss of function and wild type plants, depending on pre-growth conditions. The most prominent result of OsAKT1 overexpression was a reduction in sensitivity to osmotic/drought stress in transgenic plants: the data suggest that AKT1 overexpression improved rice osmotic and drought stress tolerance by increasing tissue levels of K(+), especially in the root.
authors.affiliation: Department of Biology, University of York, York YO10 5DD, UK.
authors.forename: Izhar
authors.initials: I
authors.lastname: Ahmad
authors.affiliation: Department of Biology, University of York, York YO10 5DD, UK.
authors.forename: Afaq
authors.initials: A
authors.lastname: Mian
authors.affiliation: Department of Biology, University of York, York YO10 5DD, UK frans.maathuis@york.ac.uk.
authors.forename: Frans J M
authors.initials: FJ
authors.lastname: Maathuis
mesh_terms: D003681:Dehydration; D012275:Oryza / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism* / Q000502:physiology; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D030821:Plants, Genetically Modified; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism* / Q000502:physiology
chemical_list: D010940:Plant Proteins; D015221:Potassium Channels; D011188:Potassium
keywords: Drought; Oryza sativa; OsAKT1; ion channel; osmotic stress; rice.