Abstract:【Background】Introduced since 1950s, giant ragweed is one of main invasive plants in China and has caused great economic losses. The giant ragweed rust (Puccinia xanthi f.sp.ambrosiaetrifida) is a potential new agent for biological control. A detailed studyof the infection process would help to develop biologcial control options against this invasive species. 【Method】Physiological studies were carried out to evaluate the potential of the pathogen to be used to control giant ragweed, including electrical conductivity, the contents of malonaldehyde (MDA), superoxide radical (O[SX(B-*3]-[]·[SX)]2), ascorbic acid (AsA), proline (Pro) in infested ragweed leaves at different stages of infection. 【Result】The electrical conductivity increased with the increasing of disease severity and length of infection time, which indicated that the rust damaged the cell membrane of leaves and caused electrolytic exosmosis. At the initial stage of the infection, the contents of MDA and O[SX(B-*3]-[]·[SX)]2 increased, the content of O[SX(B-*3]-[]·[SX)]2 was highest at disease severity grade 3, while MDA content was highest at disease severity 4. AsA content continued to increase, and Pro content decreased during the last infection stage, which indicated that resistance was not significant and Pro content probably had a more important effect in the normal functioning of leaves. 【Conclusion and significance】The leaf physiology and biochemistry was destroyed in the process of ragweed rust infection, which will provide reference for further exploring the pathogenesis and fully developing the potential of the pathogen to control ragweed.
