• gray mold
• plant protection
• gene knockdown
• RNAi

The necrotrophic plant pathogenic fungus Botrytis cinerea, causal agent of gray mold disease, causes significant losses in agricultural production. The control of this fungal pathogen is rather difficult due to its wide host range and also to its environmental persistence. Currently, its management is still mainly based on chemicals, which are harmful not only on the environment and human health, but also because they favour the development of fungicide-resistant strains. In this scenario, the non-transformative RNA interference (RNAi)-based technology called Spray-Induced Gene Silencing (SIGS), is gaining interest as versatile, sustainable, effective, and environmentally-friendly alternative to the use of chemicals in crop protection. In this PhD research project, the SIGS approach was evaluated for controlling B. cinerea infection on lettuce (Lactuca sativa L.) plants. In particular, the key genes were carefully selected: two mitogen-activated protein kinases BcBmp1 and BcBmp3 controlling many fungal processes connected to pathogenesis and the BcPls1 tetraspanin gene, with an important role as virulence factor in appressoria forming pathogens as B. cinerea. The dsRNA delivery was realized by the spray technique where the use of nanocarriers was evaluated for enhancing the stability of dsRNA molecules. In addition, the in vivo production of double stranded RNA was investigated as potential alternative to the in vitro synthesis, aimed to improve the yield and reducing the cost of the process. RNAi-based biocontrol could be an excellent alternative to chemical fungicide and several RNAi-based products are expected to be approved in the next future, albeit they will face several challenges before reaching the market.