• gene knockdown
• B. cinerea
• dsRNA
• RNAi
• SIGS

Botrytis cinerea, the causal agent of grey mould, can infect more than 500 plant species and is considered the second most harmful fungal plant pathogen. The pathogen is mainly controlled through chemical strategies but increasing concerns about chemical fungicides and the development of fungicide resistance strains motivated to investigate more sustainable alternatives. RNA interference has recently been considered and topical application of double-strand RNAs to specifically silence pathogen genes is a promising control approach. In this context, we used Escherichia coli HT115 cells and the L4440 vector to produce dsRNAs in vivo targeting three genes of B. cinerea, Bmp1, Bmp3 and Pls1. To evaluate the ability of the produced dsRNA to control B. cinerea, we sprayed Bmp1-dsRNA on lettuce plants (3 µg per plant), and after 2 days we inoculated the pathogen. As controls, we used a dsRNA unrelated to B. cinerea and water. The disease was assessed by a rating scale at 7 and 30 dpi, and the McKinney index was calculated. No significant differences were observed between treated and control plants at 7 dpi, while at 30 dpi the RNAi treatment showed an average efficacy of 18.8%. Results showed that the combination of E. coli HT115 cells and L4440 vector produced dsRNAs for all tested B. cinerea genes, but the efficiency needs to be improved. The RNAi strategy employed was successful in controlling the disease and the efficacy of the treatment could be greater using more dsRNA per plant.