Abstract
Silicon plays a significant role in the resistance of plants to multiple stresses including biotic and abiotic stresses. Although all plants rooting in the soil contain Si, the Si content of the top greatly varies with the plant species, ranging from 0.1 to 10.0% Si in dry weight. These differences have been ascribed to the uptake capacity of roots. Rice is a typical Si-accumulating plant and previous studies have shown that Si is actively taken up in the form of non-dissociated molecule, silicic acid. We characterized this transport system in rice and found that the uptake of silicic acid is mediated by a kind of transporter. This transporter contains Cys residue, but not Lys residue and has a low affinity for silicic cid (Km 0.32 mM). To clone a gene encoding the Si transporter, a rice mutant defective in Si uptake has been isolated and characterized.
