The Life Cycle and Ultrastructure of the Host Response of the Smut Pathogen Anthracocystis destruens on Broomcorn Millet

Broomcorn millet smut caused by the fungus is one of the most destructive diseases in broomcorn millet production. The life cycle of and host defense responses against remain elusive. Here we investigated the disease symptom development and the parasitic process of as well as the ultrastructure of the host-pathogen interface. The results showed that there are four typical symptoms of broomcorn millet smut, which are blackfly, cluster leaves, hedgehog head, and incomplete fruiting. colonizes all tissues of broomcorn millet but produces teliospores only in the inflorescence. After infection, proliferates in the host, likely in a systemic manner. Ultrastructural study of the infected inflorescence showed that the pathogen grows intercellularly and intracellularly within the host. The host activates defense response to prevent pathogen infection, accumulation of callose analogs and highly electron-dense deposits to resist infection.