Ethylene Plays a Dual Role during Infection by of .

infection leads to hypertrophy of host roots and subsequent formation of galls, causing huge economic losses to agricultural producers of plants. Ethylene (ET) has been reported to play a vital role against necrotrophic pathogens in the classic immunity system. More clues suggested that the defense to pathogens in roots may be different from the acrial. The ET pathway may play a positive role in the infection of . , as shown by recent transcriptome profiling. However, the molecular basis of ET remains poorly understood. In this study, we investigated the potential role of ethylene against . infection in an double-mutant of (). After infection, (Disease Index/DI: 93) showed more susceptibility compared with wild type (DI: 75). Then, we inoculated () with . by 1-aminocyclopropane-1-carboxylic acid (ACC) and pyrazinamide (PZA), respectively. It was found that the symptoms of infected roots with ACC were more serious than those with PZA at 20 dpi (day post infection). However, the DI were almost the same in different treatments at 30 dpi. can be directly regulated by ET and was upregulated at 7 dpi with ACC, as shown by qRT-PCR. The mutant of (DI: 93.75) was more susceptible than the wild type in . Thus, our work reveals the dual roles of ET in infection of and provides evidence of ET in root defense against pathogens.