Wheat-faba bean intercropping can control Fusarium wilt in faba bean under F. commune and ferulic acid stress as revealed by histopathological analysis

Fusarium wilt, is an important soilborne disease restricting the cultivation of faba bean. Wheat-faba bean intercropping is one of the useful means to control Fusarium wilt in faba bean. In this study, we analyzed the histopathological effect of wheat-faba bean intercropping system on Fusarium wilt in faba bean under F. commune and ferulic acid stress. Faba bean was inoculated with F. commune. Various concentrations of ferulic acid were added to the inoculated plants to study the occurrence of Fusarium wilt, growth of faba bean seedlings, activity of cell-wall-degrading enzymes (CWDEs) produced by F. commune in stems, and structural changes in stem tissues under monocropping and intercropping systems. When ferulic acid was added to the faba bean plants inoculated with F. commune, wheat-faba bean intercropping significantly reduced the activity of CWDEs. Microstructure observation revealed that the xylem vessel was thickened, and xylem parenchymal tissue and vascular cambium produced gelatinous substance and tylose. Moreover, callose deposition was reduced in the sieve tube; death rate of vascular tissue, cortex tissue, and epidermis tissue was reduced, and faba bean biomass was observably increased. The combination of these factors reduced the occurrence of Fusarium wilt. Therefore, wheat-faba bean intercropping reduced the severity of Fusarium wilt in faba bean by decreasing the activities of CWDEs and increasing tissue structure integrity.