The bacterial potassium transporter gene MbtrkH improves K(+) uptake in yeast and tobacco

K(+) is an essential nutrient for plant growth and is responsible for many important physiological processes. K(+) deficiency leads to crop yield losses, and overexpression of K(+) transporter genes has been proven to be an effective way to resolve this problem. However, current research on the overexpression of K(+) transporter genes is limited to plant sources. TrkH is a bacterial K(+) transporter whose function generally depends on the regulation of TrkA. To date, whether TrkH can improve K(+) uptake in eukaryotic organisms is still unknown. In this study, a novel MbtrkH gene was cloned from marine microbial metagenomic DNA. Functional complementation and K(+)-depletion analyses revealed that MbTrkH functions in K(+) uptake in the K(+)-deficient yeast strain CY162. Moreover, K(+)-depletion assays revealed that MbtrkH overexpression improves plant K(+) uptake. K(+) hydroponic culture experiments showed that, compared with WT tobacco lines, MbtrkH transgenic tobacco lines had significantly greater fresh weights, dry weights and K(+) contents. These results indicate that MbTrkH promotes K(+) uptake independently of TrkA in eukaryotes and provide a new strategy for improving K(+)-use efficiency in plants.