FIGURE 6.

Plant phenotypes of rice plant exposed to high temperature. (A) Seedlings of Stvb-i–silenced lines and the WT St No. 1 at the end of heat treatment at 35–37°C for 4 days at the 1st-leaf stage. Heat-treated plants exhibited chlorosis and short crown roots (yellow arrowheads), whereas non-heated seedlings did not. Scale bar: 3 cm. (B) Appearance of Stvb-i–silenced plants and Stvb-i–complemented plants at 5, 28, and 56 days after the end of heat treatment (the same condition to panel A). Upper panel; representative heat-treated seedlings grown at 25°C in a growth chamber for 5 days after the end of the heat treatment. Middle and lower panels; plants grown for 28 and 56 days, respectively, after the heat treatment. Untreated plants were employed as controls for heated plants. Scale bars: 10 cm. (C) Plant height of Stvb-i–silenced lines (St507 and St509) and the WT St No. 1 exposed to high temperature. Seedlings of at the 1st-leaf stage were left untreated or were treated at 38°C for 2 days once or three times. Light yellow shading represents heating periods. Asterisks show significant differences between both Stvb-i–silenced lines and WT (Tukey–Kramer test, p < 0.01, n = 20).