Overexpression of the rice AKT1 potassium channel affects potassium nutrition and rice drought tolerance

• Published in: Journal of experimental botany 2016-04, Vol.67 (9), p.2689-2698
• Main Authors: Ahmad, Izhar, Mian, Afaq, Maathuis, Frans J. M.
• Format: Article
• Language: English
• Subjects: Dehydration; Oryza - metabolism; Oryza - physiology; Plant Proteins - metabolism; Plant Proteins - physiology; Plant Roots - metabolism; Plant Shoots - metabolism; Plants, Genetically Modified; Potassium - metabolism; Potassium Channels - metabolism; Potassium Channels - physiology; RESEARCH PAPER
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erw103

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.