Abstract
Rice requires a large amount of Si for high productivity, especially at the reproductive stage. Recently, we identified three Si transporters in rice. Lsi1 and Lsi2 are involved in the efficient Si uptake by rice roots, while Lsi6 in the xylem unloading of silicic acid. Here we report a novel important role of Lsi6 in Si distribution at rice reproductive stage.
After heading stage, Lsi6 was highly expressed in the nodes in the upper parts of the stem and localized at the xylem parenchyma cells of the large vascular bundles. Knockout of Lsi6 resulted in decreased Si accumulation in the panicles and increased Si accumulation in the flag-leaf. Water-loss from excised immature panicles significantly increased in the knockout line. These results suggest that Lsi6 is involved in xylem unloading of Si in the nodes and is necessary for re-loading onto the vascular tissues toward the panicles.
