Abstract:

The active oxygen outbreaks of pumpkin inbred line 112-2 and ‘Jiujiangjiaoding’ infected with powdery mildew were observed to explore the correlation of ROS with the resistance of pumpkin to powdery mildew. DAB-dyed spots represented H₂O₂ accumulation and NBT-dyed spots represented O₂^- accumulation. The results showed that at the seedling stage, the inbred line 112-2 and ‘Jiujiangjiaoding’ were inoculated with powdery spores at 0 h, and a small amount of DAB-dyed spots were observed at 72 h, and the DAB-dyed spots expanded and deepened from 96 h to 144 h. The inbred line 112-2 and ‘Jiujiangjiaoding’ were inoculated with powdery spores at 0 h, NBT-dyed spots began to appear at 24 h, the NBT-dyed spots continued to expand and deepened from 48 h to 144 h. In the fruiting period, the two materials were inoculated with powdery mildew spores at 0 h, DAB-dyed spots were observed in inbred line 112-2 at 48 h, and the spots enlarged and deepened from 72 h to 144 h; DAB-dyed spots were observed at 72 h from the ‘Jiujiangjiaoding’, and the spots expanded and deepened from 96 h to 144 h. The inbred line 112-2 and ‘Jiujiangjiaoding’ were inoculated with powdery spores at 0 h; NBT-dyed spots began to appear at 48 h, the NBT-dyed spots expand and deepened from 72 h to 144 h. The inbred line 112-2 produced H₂O₂ and O₂^- faster than the ‘Jiujiangjiaoding’ and the difference in accumulation amount reached the maximum at 144 h. In conclusion, the accumulation of H₂O₂ and O₂^- in the resistant material inoculated with powdery mildew is faster and more than the susceptible material.

Key words: pumpkin, powdery mildew, ROS, H₂O₂, O₂^-