Abstract
Rice is a typical Si accumulator and it requires a large amount of Si for high yield production. We have identified two genes (Lsi1 and Lsi2) encoding Si transporters in rice roots. Here, we characterized the function of Lsi6, a close homolog of Lsi1, in rice. Expression of Lsi6 in Xenopus oocyte also showed transport activity for Si. Unlike Lsi1 and Lsi2, Lsi6 was expressed in both the root and shoot. Immunohistological staining showed that Lsi6 protein was localized at the xylem parenchyma in the leaf sheath and leaf blade. When this gene was knocked out in a T-DNA line, Si uptake by the roots was unaffected, but silicification of leaf abaxial epidermis was frequently observed than wild type. These results suggest that Lsi6 is involved in the xylem unloading and subsequent distribution of Si in the shoot.
