Figure 4. ROS burst in leaves of transgenic line H213 dipped in a conidial suspension of V. dahliae.

(a) In situ observation of ROS in cotton leaves dipped in a conidial suspension of V. dahliae with DAB staining. The strong, brown precipitate was observed in leaves of parent W0 plants 8 hr after inoculation with V. dahliae and in leaves of transgenic line H213 plants 1 hr or 5 hr after inoculation with V. dahliae. At least six independent leaves were used for this experiment. A stereomicroscope (Olympus, DP72, Japan) was used for photographing the leaves under white light. Scale bars = 5mm. (b) H₂O₂ content (μM/g fresh weight) in leaves of transgenic line H213 and parent W0 plants dipped in a conidial suspension of V. dahliae. Error bars represent ± SE, n = 6. (c,d) The PR genes were activated in transgenic line H213 after inoculation with V. dahliae. Three biological replicates were used for each reaction with three technical replicates each. Mean values and standard errors were calculated from three biological replicates (**P ≤ 0.01, by student’s t test).