Foliar Application of Silicon Enhances Resistance Against Through the ET/JA- and NPR1- Dependent Signaling Pathways in Potato.

Late blight (LB), caused by the oomycete pathogen , is a devastating disease of potato that is necessary to control by regularly treatment with fungicides. Silicon (Si) has been used to enhance plant resistance against a broad range of bacterial and fungal pathogens; however, the enhanced LB resistance and the molecular mechanisms involving the plant hormone pathways remain unclear. In this study, Si treatment of potato plants was found to enhance LB resistance in both detached leaves and living plants accompanied by induction of reactive oxygen species (ROS) production and pathogenesis-related genes expression. Regarding the hormone pathways involved in Si-mediated LB resistance, we found a rapidly increased content of ethylene (ET) 15 min after spraying with Si. Increased jasmonic acid (JA) and JA-Ile and decreased salicylic acid (SA) were identified in plants at 1 day after spraying with Si and an additional 1 day after EC1 infection. Furthermore, pretreatment with Me-JA enhanced resistance to EC1, while pretreatment with DIECA, an inhibitor of JA synthesis, enhanced the susceptibility and attenuated the Si-mediated resistance to LB. Consistent with these hormonal alterations, Si-mediated LB resistance was significantly attenuated in -, -, -, -, -, and repressed plants but not in and repressed plants using virus-induced gene silencing (VIGS). The Si-mediated accumulation of JA/JA-Ile was significantly attenuated in -, -, and - plants but not in -, and plants. Overall, we reveal that Si can be used as a putative alternative to fungicides to control LB, and conclude that Si-mediated LB resistance is dependent on the ET/JA-signaling pathways in a and dependent manner.