BioClay™ prolongs RNA interference‐mediated crop protection against Botrytis cinerea

Abstract

One of the most promising tools for the control of fungal plant diseases is spray‐induced gene silencing (SIGS). In SIGS, small interfering RNA (siRNA) or double‐stranded RNA (dsRNA) targeting essential or virulence‐related pathogen genes are exogenously applied to plants and postharvest products to trigger RNA interference (RNAi) of the targeted genes, inhibiting fungal growth and disease. However, SIGS is limited by the unstable nature of RNA under environmental conditions. The use of layered double hydroxide or clay particles as carriers to deliver biologically active dsRNA, a formulation termed BioClay™, can enhance RNA durability on plants, prolonging its activity against pathogens. Here, we demonstrate that dsRNA delivered as BioClay can prolong protection against Botrytis cinerea, a major plant fungal pathogen, on tomato leaves and fruit and on mature chickpea plants. BioClay increased the protection window from 1 to 3 weeks on tomato leaves and from 5 to 10 days on tomato fruits, when compared with naked dsRNA. In flowering chickpea plants, BioClay provided prolonged protection for up to 4 weeks, covering the critical period of poding, whereas naked dsRNA provided limited protection. This research represents a major step forward for the adoption of SIGS as an eco‐friendly alternative to traditional fungicides.

Artificial nanovesicles for dsRNA delivery in spray induced gene silencing for crop protection

“…This is similar to the extended protection provided by inorganic dsRNA complex formulations against viruses on Nicotiana tabacum cv. Xanthi leaves and fungal pathogens on tomato plants 27,34 . Another key advantage of utilizing liposome technology for crop protection, especially post-harvest products, is that the success of similar formulations in clinical applications 47 suggests that the AVs will be safe for human consumption.…”

“…These studies demonstrate crosskingdom RNAi is a conserved mechanism across different species, including plant and animal hosts. Consequently, SIGS RNAs which target genes involved in RNAi machinery and in sRNA biogenesis have proven to be quite effective [7][8]10,23,[25][26][27][28] , making them ideal biological pathways to target in other organisms. Furthermore, because RNAi can tolerate multiple mismatches between sRNAs and target RNAs 29 , fungal pathogens are less likely to develop resistance to SIGS RNAs than to traditional fungicides, which mostly bind to and inhibit a specific enzyme or protein.…”

“…Ultimately, this can provide RNAi-based systemic protection against several plant viruses for at least 20 days after topical application 34,37 . This nanotechnology was recently proven to be effective for plant protection against fungal pathogens 27 .…”

Plant biomacromolecule delivery methods in the 21st century

“…Nanoparticle-cargo conjugates can be delivered through leaf infiltration using a needless syringe in a lab research context, and for scalable field applications, there are some studies demonstrating the feasibility of topical application of doublestranded RNA (dsRNA) and siRNA cargoes with layered double hydroxide (LDH) nanoparticles (Mitter et al, 2017) and carbon dots (Schwartz et al, 2020) (Figure 1D), which eliminates the issues of the instability of naked RNA sprayed on plants. The LDH platform, which is called BioClay, enabled virus/fungus protection for 21 days when sprayed on virus/fungus-challenged leaves (Mitter et al, 2017;Niño-Sánchez et al, 2022). More recently, the BioClay technology has been topically applied for dsRNA delivery into tomato pollen (Yong et al, 2021), extending the plant tissue types for various applications.…”

Towards dsRNA‐integrated protection of medical Cannabis crops: considering human safety, recent‐ and developing RNAi methods, and research inroads

“…42,[74][75][76] Notably, Worrall et al 74 observed inhibition of aphid-mediated virus transmission between plants after spraying dsRNA-BioClay (dsRNAloaded, biodegradable, layered double hydroxide clay nanosheets) targeting a plant virus. More recently, Jain et al 42 demonstrated the capacity of dsRNA-BioClay in protecting sprayed plants from all life stages of the whitefly B. tabaci, and Niño-Sánchez et al 77 demonstrated prolonged plant protection against Botrytis cinerea Pers., using dsRNA-BioClay spray, compared to naked dsRNA. DsRNA-BioClay spray technology is currently being further developed through a partnership between the agricultural chemical company Nufarm (Melbourne, Australia) and the University of Queensland.…”