RNA interference-mediated targeting of monooxygenase SsMNO1 for controlling Sclerotinia stem rot caused by Sclerotinia sclerotiorum

Background: Sclerotinia sclerotiorum is a devastating fungal pathogen that poses a threat to a variety of economically important crops. Owing to the lack of highly resistant cultivars and the prolonged survival of sclerotia, effective control of Sclerotinia diseases remains challenging. RNA interference (RNAi) agents targeting essential active transcripts of genes associated with the development and virulence of pathogens are a valuable and promising disease control method.

Results: Our finding suggested that a flavin adenine dinucleotide (FAD)-dependent monooxygenase gene SsMNO1 plays pivotal roles in the hyphal growth, sclerotial development, and virulence of S. sclerotiorum, rendering it a potential target for RNAi-mediated management of S. sclerotiorum. The external application of double-stranded RNA (dsRNA) targeting SsMNO1 inhibited sclerotial development in artificial media and plant tissues. Furthermore, dsRNA significantly reduced the hyphal virulence of S. sclerotiorum in host plants by interfering with SsMNO1 expression. The inhibitory activity persisted for over 1 week on the surface of Brassica napus. Artificial small interfering RNA (siRNA) targeting SsMNO1 also exhibited inhibitory effects. Transgenic Arabidopsis thaliana plants expressing SsMNO1 hairpin RNAi constructs showed increased resistance to S. sclerotiorum infection. Notably, the total RNA extracts from SsMNO1-RNAi plants also reduced the hyphal virulence in Brassica napus.

Conclusions: Therefore, RNAi agents targeting SsMNO1 have dual effects on sclerotial development and hyphal virulence, rendering it an ideal target for controlling diseases caused by S. sclerotiorum. © 2024 Society of Chemical Industry.