Under white light, a significant increase in PAL activity was observed only after 48 h of inoculation. Under natural light, however, activity did not increase in
M. oryzae-inoculated leaves at any time. In DW-treated leaves,
a significant increase was observed after 48 h in plants treated with
red light, but not at any time in plants treated with natural or white
light (Fig. 2b). These results suggest that PAL activity is increased in
rice leaves treated with red light and that this increased activity
plays an important role in resistance againstM. oryzae