FANA and Morpholino's, Novel Molecules for Gene-Targeting in Plants and Arthropods

Considering the resistance of conventional pesticides there is an ever growing need for new technologies to protect plants. Recently novel RNA silencing and cell regulation approaches have been shown to be of extreme value. However, efficient delivery of such emerging technologies for the control and management of agricultural pests, and pathogens of animal and plants, are critical to their success. In this study, we successfully tested the delivery into plants and subsequently insects (Hemiptera and Coleoptera) with two RNA silencing and regulation products. Specifically we used, self-delivering FANA antisense oligonucleotides (FANA ASOs) that knocks down the target mRNA by cleaving the target mRNA (after RNase H mediated cleavage of the mRNA target FANA ASOs are instantaneously recycled to target other copy numbers of the target and thus can target multiple copy numbers) and morpholino oligonucleotides (PPMO) that use a cell penetrating peptide conjugate for delivery and acts as translational blockers (since morpholinos are independent of RNase H mechanism, one morpholino can only target one copy number of a gene). FANA ASOs provide a superior RNA silencing alternative to existing RNAi strategies that have low efficacy, big delivery challenges and high manufacturing costs. Further, FANA ASOs are known to be non-toxic, are highly stable and provide a highly target specific gene knockdown. The capability of FANA ASOs to efficiently self-deliver without the use of any formulation, conjugate or carrier make them very attractive for topical spray applications. Topical sprays onto citrus leaves, root absorption, and tree trunk injections using FANA ASOs and PPMOs were evaluated. Both FANA ASOs and PPMOs were designed against a range of targets: Coleopteran, Citrus root weevil; Hemipteran, Asian citrus psyllid, and a Plant pathogenic bacteria of citrus, Candidatus Liberibacter asiaticus. We observed successful increase in insect mortality and reduced bacteria within the insects and/or citrus trees. This is the first evidence for successful delivery of FANA ASOs and PPMO by plant delivered targeting strategies to manage agricultural arthropod pests and plant pathogens.