Crop protection by RNA interference: a review of recent approaches, current state of developments and use as of 2013

Abstract RNAi-based applications aim to inhibit the expression of specific essential genes in target organisms by uptake and processing of double-stranded RNA and subsequent degradation of target gene mRNA. While the research on RNAi-based pesticides was initially limited to endogenous applications (i.e., production of the dsRNA by the crop), the development of technologies for exogenous applications like RNAi sprays in particular has increased in recent years. Due to the assumed beneficial properties of RNA molecules, such as degradability or target specificity, RNAi technology receives increasing attention in the development of plant protection products, as evidenced by a steadily increasing number of publications. A horizon scan was conducted with a specific emphasis to identify and illustrate the current state of RNAi developments and applications in crop protection as well as their biomanufacturing readiness levels. In this study, more than 180 publications were evaluated. Furthermore, we identified 268 patent families on this topic. A large variety with regard to treated crops, targeted pest species and target gene functions as well as application types was observed. In total, RNAi applications for more than 30 different pest species were identified, most of which belonged to the insect orders Lepidoptera, Hemiptera and Coleoptera. In addition, applications targeting fungi and viruses were found. RNAi applications were identified to be an upcoming topic in crop protection and, therefore, are becoming increasingly relevant for environmental risk assessment, due to the high number of targeted pest species as well as the variety of novel application types. With this review, we inform future work aimed to develop further adequate concepts and methods for environmental risk assessment of RNAi-based applications.