Genetic modification in Malaysia and India: current regulatory framework and the special case of non-transformative RNAi in agriculture

Size variations of mesoporous silica nanoparticle control uptake efficiency and delivery of AC2-derived dsRNA for protection against tomato leaf curl New Delhi virus

KEY MESSAGE

We report the size dependent uptake of dsRNA loaded MSNPs into the leaves and roots of Nicotiana benthamiana plants and accessed for their relative reduction in Tomato leaf curl New Delhi viral load. A non-GMO method of RNA interference (RNAi) has been recently in practice through direct delivery of double stranded RNA into the plant cells. Tomato leaf curl New Delhi virus (ToLCNDV), a bipartitie begomovirus, is a significant viral pathogen of many crops in the Indian subcontinent. Conventional RNAi cargo delivery strategies for instance uses viral vectors and Agrobacterium-facilitated delivery, exhibiting specific host responses from the plant system. In the present study, we synthesized three different sizes of amine-functionalized mesoporous silica nanoparticles (amino-MSNPs) to mediate the delivery of dsRNA derived from the AC2 (dsAC2) gene of ToLCNDV and showed that these dsRNA loaded nanoparticles enabled effective reduction in viral load. Furthermore, we demonstrate that amino-MSNPs protected the dsRNA molecules from nuclease degradation, while the complex was efficiently taken up by the leaves and roots of Nicotiana benthamiana. The real time gene expression evaluation showed that plants treated with nanoparticles of different sizes ~ 10 nm (MSNPDEA), ~ 32 nm (MSNPTEA) and ~ 66 nm (MSNPNH3) showed five-, eleven- and threefold reduction of ToLCNDV in N. benthamiana, respectively compared to the plants treated with naked dsRNA. This work clearly demonstrates the size dependent internalization of amino-MSNPs and relative efficacy in transporting dsRNA into the plant system, which will be useful in convenient topical treatment to protect plants against their pathogens including viruses. Mesoporous silica nanoparticles loaded with FITC, checked for its uptake into Nicotiana benthamiana.

Recent Progress on Nanocarriers for Topical-Mediated RNAi Strategies for Crop Protection—A Review

To fulfil the growing needs of the global population, sustainability in food production must be ensured. Insect pests and pathogens are primarily responsible for one-third of food losses and harmful synthetic pesticides have been applied to protect crops from these pests and other pathogens such as viruses and fungi. An alternative pathogen control mechanism that is more “friendly” to the environment can be developed by externally applying double-stranded RNAs (dsRNAs) to suppress gene expression. However, the use of dsRNA sprays in open fields is complicated with respect to variable efficiencies in the dsRNA delivery, and the stability of the dsRNA on and in the plants, and because the mechanisms of gene silencing may differ between plants and between different pathogen targets. Thus, nanocarrier delivery systems have been especially used with the goal of improving the efficacy of dsRNAs. Here, we highlight recent developments in nanoparticle-mediated nanocarriers to deliver dsRNA, including layered double hydroxide, carbon dots, carbon nanotubes, gold nanoparticles, chitosan nanoparticles, silica nanoparticles, liposomes, and cell-penetrating peptides, by review of the literature and patent landscape. The effects of nanoparticle size and surface modification on the dsRNA uptake efficiency in plants are also discussed. Finally, we emphasize the overall limitation of dsRNA sprays, the risks associated, and the potential safety concerns for spraying dsRNAs on crops.

Is Malaysia Ready for Human Gene Editing: A Regulatory, Biosafety and Biosecurity Perspective

Gene editing platforms have revolutionized the field of genetics with a direct impact on the public health system. Although there are apparent benefits, it is often accompanied by public debates over its uncertainties and risks. In the Malaysian context, modern biotechnology has raised questions about how to best govern gene editing in regulations, biosafety, and biosecurity. Even though standards and guidelines on stem cell and cell-based therapies have been developed, there are no appropriate legal frameworks available for gene editing yet. Nevertheless, biosafety regulations were established to balance promoting biotechnology and protecting against their potential environmental and human health risks. There is also a need to address the potential of genetically modified organisms (GMOs) as bioweapons. Numerous frameworks from several international organizations may provide valuable input in formulating documents on gene editing. By establishing comprehensive guidelines, legal policies, and standards to tackle the challenges and risks associated with gene editing, Malaysia can successfully apply this modern technology in this country.

Negligible transcriptome and metabolome alterations in RNAi insecticidal maize against Monolepta hieroglyphica

RNAi-based genetically modified maize resistant to Monolepta hieroglyphica (Motschulsky) was demonstrated with negligible transcriptome and metabolome alterations compared to its unmodified equivalent. As one of the most prevalent insect pests afflicting various crops, Monolepta hieroglyphica (Motschulsky) causes severe loss of agricultural and economic productivity for many years in China. In an effort to reduce damages, in this study, an RNA interference (RNAi)-based genetically modified (GM) maize was developed. It was engineered to produce MhSnf7 double-stranded RNAs (dsRNAs), which can suppress the Snf7 gene expression and then lead M. hieroglyphica to death. Field trail analysis confirmed the robustly insecticidal ability of the MhSnf7 GM maize to resist damages by M. hieroglyphica. RNA sequencing analysis identified that only one gene was differentially expressed in the MhSnf7 GM maize compared to non-GM maize, indicating that the transcriptome in MhSnf7 GM maize is principally unaffected by the introduction of the MhSnf7 dsRNA expression vector. Likewise, metabolomics analysis identified that only 8 out of 5787 metabolites were significantly changed. Hence, the integration of transcriptomics and metabolomics demonstrates that there are negligible differences between MhSnf7 GM maize and its unmodified equivalent. This study not only presents a comprehensive assessment of cellular alteration in terms of gene transcription and metabolite abundance in RNAi-based GM maize, but also could be used as a reference for evaluating the unintended effect of GM crops.

Problem Formulation for Off-Target Effects of Externally Applied Double-Stranded RNA-Based Products for Pest Control

Externally applied dsRNA-based biocontrol products may lead to off-target degradation of messenger RNA in target and non-target organisms. For the purposes of regulatory risk assessment of such products, producing a comprehensive catalog of any off-target effects using profiling methods is unnecessary and would be ineffective in supporting decision-making. Instead, problem formulation should derive criteria that indicate acceptable risk and devise a plan to test the hypothesis that the product meets those criteria. The key to effective risk assessment of dsRNA-based biocontrols is determining whether their properties indicate acceptable or unacceptable risk, not whether they arise from on- or off-target effects of dsRNA.