Flower organs from U. virens-infected panicles showed enhanced brown oxidized DAB precipitates (Figures 2(a)-(c)), in contrast,the flower organs from the control plants did not exhibit 
brown color (Figures 2(d)-(f)). We cut the ovaries from both the U. virens-infected and the control plants and examined the DAB oxidation under microscope, the ovaries from U. virens-infected plants displayed more DAB oxidation products than those from uninfected plants (Figures 2(a), (d)), especially, the base of the infected ovary showed the highest level of oxidation, indicating 
more ROS produced at this site. Probably, the base of the ovary is the place where the fungus obtains water and nutrients from host plant.