FIGURE 7.

Induction of immune responses in cultured rice cells by several mutant flagellins. A, time course of H₂O₂ generation in cultured rice cells that were treated with several mutant flagellins. White columns, 0 h after treatment; gray columns, 1 h after treatment; black columns, 3 h after treatment; hatched columns, 6 h after treatment. The y axis represents the -fold change in H₂O₂ in cultured rice cells relative to the levels before flagellin treatment. Asterisks indicate a significant increase (t test; p < 0.05) in H₂O₂ generation with the amino acid-substituted flagellins. B, PAL mRNA levels in cultured rice cells that were treated with several mutant flagellins. The mRNA levels were calculated from the threshold point located in the log-linear range of RT-PCR. Standard samples with known template amounts were used to quantitate the PAL mRNA levels. The y axis represents the -fold change relative to the PAL mRNA levels of water-treated cultured rice cells. White columns, 0 h after treatment; black columns, 6 h after treatment. C, Cht-1 mRNA levels in cultured rice cells that were treated with several mutant flagellins. The mRNA levels were calculated from the threshold point located in the log-linear range of RT-PCR. Standard samples with known template amounts were used to quantitate the Cht-1 mRNA levels. The y axis represents the -fold change relative to the Cht-1 mRNA levels of water-treated cultured rice cells. White columns, 0 h after treatment; black columns, 6 h after treatment. The error bars indicate the S.D. for five experiments. KΔFlaA-KFlaA, K1-type flagellin purified from the KΔFlaA strain possessing the K1 FlaA expression vector; K-178S/A, S178A substituted flagellin; K-183S/A, S183A substituted K1 flagellin; K-212S/A, S212A substituted K1 flagellin; K-351T/A, T351A substituted K1 flagellin; K-178,183S/A, S178A/S183A double substituted flagellin and N1141 flagellin purified from the NΔFlaA strain carrying the N1141 FlaA expression vector.