Abstract:

The relationship between the host resistance and dynamic changes of superoxide anion (O₂^－·), hydrogen peroxide (H₂O₂), peroxidase (POD), phenylalanine ammonia lyase (PAL) and chitinase was analyzed in the interaction between poplar species or varieties (Populus deltoides, P. szechuanica, Populus×euramericana cv.‘Guarieto’ , Populus×euramericana cv.‘Polska 15 A’ , Populus deltoides× P. nigra) and Melampsora larici-populina (MLP) isolates (Gl₀₅₂, Sb₀₅₂). The results showed that the host ROS metabolism and the changes of the resistance-related enzymes were significantly different in the interaction between different poplars and different MLP isolates. The rate of O^－·₂ production and content of H₂O₂ in the host of immune, resistance species and varieties quickly increased on the highest level respectively at 0.5 day and 1day after inoculation, and appeared 1～2 peaks thereafter, but the ROS of the susceptible varieties lightly increased through the process. The activities of SOD and POD were negatively correlated with the poplar resistance. PAL activity increased rapidly and infensively in 2 day in the host of immune and high resistance poplars, while it did not obviously change in the susceptible one after inoculation. The chitinase activity was positively correlated with poplar resistance.

Key words: poplar, Melampsora larici-populina, reactive oxygen species, enzymes activity