Plants and fungi natively regulate expression of genes through the RNA interreference (RNAi) pathway, a mechanism where small interfering RNAs (19-21 base pairs in length) bind to target mRNAs leading to catalytic degradation of the mRNA. Degradation of the target mRNA prevents its translation into protein, effectively silencing the gene. Importantly, this process is highly specific, relying on perfect complementarity between the siRNA and the target mRNA, which significantly limits off-target effects. Plants have been engineered to produce siRNA that can be delivered into the invading fungi to interfere with gene function in the fungus, in a process known as host-induced silencing (HIGS). HIGS in wheat has shown ability to control fusarium graminearum growth, establishing RNAi as a viable means for controlling fungi growth. However, consumer opposition to genetically modified plants limits the widespread application of HIGS. Here, we will discuss approaches for developing non-toxic and biocompatible nanoparticles composed of natural products for the delivery of siRNA to plants. Specifically, we focus on the development of spherical nucleic acids, nanoparticle consisting of a spherical core with a dense and highly oriented nucleic acid shell, as potential fungicidal vehicles. We are currently developing liposome- and micelle- based structures for targeting susceptibility genes in wheat and virulence genes in f graminearum with the goal of mitigating FHB.
ACKNOWLEDGEMENT AND DISCLAIMER
This material is based upon work supported by the U.S. Department of Agriculture under a Non-Assistance Cooperative Agreement No. 58-5020-1-013. This is a cooperative project with the U.S. Wheat & Barley Scab Initiative. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.