Figure 5.

Shoot Si Concentration and Si Concentration in the Leaf Guttation Fluid and Xylem Sap.

(A) Shoot Si concentration. Two-week-old seedlings of wild-type rice (cv Dongjin) and the Lsi6 T-DNA line grown hydroponically without Si were transferred to 1.2-liter plastic pots containing 1 kg of soil with or without silica fertilizer (high and low Si, respectively). Three weeks later, the aboveground parts were harvested to measure Si concentration. Means ± sd of biological replicates (n = 3) are shown.

(B) and (C) Si concentration in the leaf guttation fluid and xylem sap.

(B) Four-week-old seedlings of wild-type rice (cv Dongjin) and the T-DNA insertion mutant (T-DNA) were cultured on hydroponic medium with 0.5 mM Si in the greenhouse under natural right. Guttation fluid was collected just after sunset and then xylem sap was collected from the cut end of the shoot basal region for Si measurement. Means ± sd of biological replicates (n = 4) are shown.

(C) Four-week-old seedlings of the wild type (WT1, cv Dongjin; WT2, cv Nipponbare), the Lsi6 T-DNA line (T-DNA), two independent lines of Lsi6 RNAi (RNAi-A and B), and a Tos17 insertion mutant (Tos17) were cultured on soil in pots in the greenhouse under natural right. Guttation fluid was collected just after sunset, and Si concentrations were measured. Means ± sd of three biological replicates are shown. Asterisks above a bar indicate a significant difference (P < 0.05) between the knockdown lines and the corresponding wild types by the Student's t test.