Requirements for fungal uptake of dsRNA and gene silencing in RNAi-based crop protection strategies.

Growing evidence indicates that RNAi is an effective control strategy for agronomically important fungi. To implement RNAi-based crop protection strategies, dsRNA molecules are either sprayed on foliage or generated by genetically engineered plants. Here, we summarize current knowledge of the mechanisms governing dsRNA uptake and RNAi-mediated gene silencing in fungi, as well as the factors that influence these phenomena. Of primary importance is dsRNA design, as identifying an appropriate gene for silencing and determining which region of the gene to target are critical for maximizing efficiency. Strategies for enhancing dsRNA uptake, potentially by using formulations and/or carriers that prevent dsRNA degradation by (a)biotic factors and possibly facilitate translocation, also are a key consideration. Finally, determining whether the fungal pathogen of interest contains a functional RNAi machinery is a major consideration. Integrated experimental confirmation of these important factors is necessary for the successful development of crop protection strategies against fungal pathogens.