Changes of reactive oxygen species and protective enzymes in the interaction of wheat and Puccinia striiformis f. sp. tritici.

Histological characteristics of pathogen development,production of reactive oxygen species(ROS) and activities of relative enzymes were analyzed in the incompatible and compatible interactions between wheat and Puccinia striiformis f.sp.tritici.Histological observation revealed that there were distinct differences between the incompatible interaction and compatible interaction,which included inhibition of hyphal growth,formation decrease of haustorial mother cells and haustoria,and hypersensitive cell death in host tissues occured at 18 h after inoculation(hai) in incompatible ones.The results of biochemical measuration showed the rate of O-2 production and content of H2O2 were higher in the incompatible interaction than that in the compatible interaction,and the peaks of O-2 appeared at 12 hai,H2O2 content reached its maxima at 20 hai and 72 hai.However,in the compatible interaction,the rate of O-2 production were lower or similar to control,and H2O2 content were higher than that in control but lower than in incompatible ones.The SOD activities in compatible interaction were usually higher than that in incompatible ones.At 24 hai,the CAT activities in both interactions were all higher than that in control,and CAT activities in compatible interaction were higher than that in incompatible ones at 36 hai and 48 hai,but after 60 hai,CAT activities in compatible interaction were lower than that in compatible ones again.The POD activities increased obviously in both interactions at 24 hai,but more rapidly in compatible ones.The MDA contents were increased significantly at 72 hai in incompatible interaction.The results indicated that there were striking differences about pathogen development,ROS production and relative enzymes activities in the incompatible and compatible interactions,which might have close relationship with resistance expression of wheat against stripe rust fungus.