Double-stranded RNA targeting white mold Sclerotinia sclerotiorum argonaute 2 for disease control via spray-induced gene silencing

Abstract Sclerotinia sclerotiorum , causal agent of white mold infection, is a cosmopolitan fungal pathogen that causes major yield losses in many economically important crops. Spray induced gene silencing has recently been shown to be a promising alternative method for controlling plant diseases. Based on our prior research, we focus on developing spray-induced gene silencing approach to control white mold by silencing S. sclerotiorum argonaute 2 (SsAgo2), a crucial part of the fungal small RNA pathway. We compared the lesion size as a result of targeting each ~ 500-bp segments of SsAgo2 from 5’ to 3’ and found that targeting the PIWI/ RNaseH domain of SsAgo2 is most effective. External application of double-stranded RNA (dsRNA) suppressed white mold infection using either in vitro or in vivo transcripts was determined at the rate of 800 ng/0.2cm 2 drop with a downregulation of SsAgo2 from infected leaf tissue confirmed by RT-qPCR. Furthermore, magnesium/iron-layered double hydroxides (MgFe-LDH) nanosheets were loaded by in vitro and in vivo transcribed dsRNA segments and significantly reduced the rate of lesion expansion. The combination of in vivo produced dsRNA and nanosheet is promising to be further developed as environmentally friendly fungicide to control white mold infections.