Topical delivery of host induced RNAi silencing by layered double hydroxide nanosheets: An efficient tool to decipher pathogenicity gene function of Fusarium crown and root rot in tomato

Abstract

RNAi technique was used to regulate Fusarium crown and root rot in tomatoes caused by F. oxysporum f. sp. radicis-lycopersici (FORL), by targeting three essential genes namely FoCYP51, FoChs1, and FoEF2, considering the fungicide site of action. The designed naked dsRNA was delivered on a hexagonal mono-dispersed and biodegradable layered double hydroxide (LDH) nanosheets with 30–90 nm diameter, providing high protection and stability for dsRNA with long term sustained release manner inside plant cells. The laboratory findings revealed the functional role of the three selected genes in reducing FORL's invasive growth on tomato fruits, indicating their involvement in FORL pathogenesis on tomatoes, and could be good targets for disease control using RNAi. Three different practical methods were applied for topical delivery of dsRNA into the plant cells: i) leaves spray; ii) petiole adsorption; and iii) root dipping, demonstrating three significant levels of spray-induced gene silencing (SIGS) efficacy in controlling FORL virulence infecting tomato plants. Significantly, topical spray of dsRNA delivered on LDH nanosheets provided Fusarium crown and root rot protection for at least 60 days. Obtained findings introduce critical information data on the potential to exploit spray-induced gene silencing (SIGS) as an effective alternative sustainable strategy for plant disease management. Given the ease design and production of biodegradable nano-delivery systems with high specificity and sustainability, and ease of applicability against many disease caused fungi. The use of target-specific dsRNA as an anti-fungal agent has a lot of promise and provide exceptional potential as a unique disease control and plant protection strategy.