Panama disease, or Fusarium wilt, the most serious disease in banana cultivation, is caused by Fusarium oxysporum f. sp. cubense (FOC) and has led to great economic losses worldwide. One effective way to combat this disease is by enhancing host plant resistance. The cerato-platanin protein (CPP) family is a group of small secreted cysteine-rich proteins in filamentous fungi. CPPs as elicitors can trigger the immune system resulting in defense responses in plants. In this study, we characterized a novel cerato-platanin-like protein in the secretome of Fusarium oxysporum f. sp. cubense race 4 (FOC4), named FocCP1. In tobacco, the purified recombinant FocCP1 protein caused accumulation of reactive oxygen species (ROS), formation of necrotic reaction, deposition of callose, expression of defense-related genes, and accumulation of salicylic acid (SA) and jasmonic acid (JA) in tobacco. These results indicated that FocCP1 triggered a hypersensitive response (HR) and systemic acquired resistance (SAR) in tobacco. Furthermore, FocCP1 enhanced resistance tobacco mosaic virus (TMV) disease and Pseudomonas syringae pv. tabaci 6605 (Pst. 6605) infection in tobacco and improved banana seedling resistance to FOC4. All results provide the possibility of further research on immune mechanisms of plant and pathogen interactions, and lay a foundation for a new biological strategy of banana wilt control in the future.

Barley yellow dwarf virus (BYDV), transmitted by the wheat aphid, generates serious wheat yellow dwarf disease and causes great losses in agriculture. Induced resistance has attracted great attention over recent years as a biological method to control plant pathogens and herbivores. Protein elicitor PeaT1 induces defense response in plants against fungi, viruses, and aphids. In this study, wheat seeds and seedlings were soaked and sprayed with 30 μg/mL PeaT1, respectively. Then seedlings were inoculated with BYDV by viruliferous Schizaphis graminum to detect the control efficiency of PeaT1-induced resistance against BYDV. The control efficiency was over 30% on the 14th and 21st days after the inoculation access period. Quantitative real time polymerase chain reaction (Q-RT-PCR) tests showed that there was less mRNA from the BYDV coat protein in PeaT1-treated wheat seedlings than in the control group. Electrical penetration graph (EPG) tests showed that virus transmission vector S.graminum took a longer time to find probe and feeding sites on PeaT1-treated wheat seedlings. Additionally, PeaT1-treated wheat seedlings gained higher plant height and more chlorophyll a&b. These results showed that PeaT1 efficiently controlled BYDV by inhibiting BYDV proliferation, reducing the virus transmission ability of S. graminum and alleviating the symptoms of dwarfism and yellow colouring caused by BYDV. This study provided a new integrated way to control BYDV biologically.