Abstract
Maize is able to accumulate Si at a high concentration in the shoots, but the transporters involved have not been identified. Here, we isolated and characterized three maize silicon transporter genes (ZmLsi1, ZmLsi2 and ZmLsi6), which are homologues, respectively, of rice silicon transporters (Lsi1, Lsi2 and Lsi6). Each gene shared more than 80% identity between maize and rice. Both ZmLsi1 and ZmLsi6 showed Si-influx transport activity, while ZmLsi2 showed efflux activity when they are expressed in Xenopus oocyte. ZmLsi1and ZmLsi2were expressed mainly in the roots, while ZmLsi6 was in the shoot. Immunostaining showed that ZmLsi1 was localized at the plasma membrane of root epidermal cells, while ZmLsi2 was in the endodermal cells, and ZmLsi6 was in the leaf xylem parenchyma cells. These results suggest that ZmLsi1 and ZmLsi2 are involved in the uptake of Si from the roots and ZmLsi6 is involved in the Si distribution in leaves.
