FIGURE 1.

Induction of immune responses in cultured rice cells by flagellin from A. avenae. A, time course of H₂O₂ generation in cultured rice cells that were treated with flagellin purified from the avirulent N1141 strain (solid squares) or virulent K1 strain (open circles). The y axis represents the -fold change in H₂O₂ in cultured rice cells relative to the levels before flagellin treatment. B, time course of H₂O₂ generation in cultured rice cells treated with recombinant flagellin from the avirulent N1141 strain (solid squares) or virulent K1 strain (open circles) produced in E. coli. H₂O₂ was detected using a luminol chemiluminescence assay. The y axis represents the -fold change in H₂O₂ in cultured rice cells relative to the levels before flagellin treatment. C, PAL mRNA levels in cultured rice cells that were treated with flagellin purified from the N1141 or K1 strain and recombinant flagellin of the N1141 or K1 strain. 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 in PAL mRNA levels relative to the levels in water-treated cultured rice cells. 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 error bars in all figures indicate the S.D. for five experiments.