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TECHNICAL SESSION: Novel Research Methods

Improving RNA persistence for effective control of sclerotinia stem rot: Investigating nanoparticle-based delivery systems

Monday, August 4, 2025
1:30 PM - 1:45 PM HST
Location: Room 313 C
Abstract Text: Sclerotinia sclerotiorum causes Sclerotinia stem rot (SSR) to canola and other economically important crops worldwide. Control of this pathogen relies mostly on application of chemical fungicides. Spray-induced gene silencing (SIGS) offers a cleaner alternative to manage this pathogen. The efficacy of SIGS, however, is challenged by the low durability of RNA in plant tissues and the consequent short protection time it offers. This research investigated the application of nanoparticles to enhance the efficacy of an hpRNA designed to control SSR. Five positive charged nanoparticles, Amine-Terminated NanoXact™ Silica (Asi), Layered Double Hydroxide (LDH), Chitosan (CH), Silica (Si), and Sodium montmorillonite (Na-MMT) were evaluated. Fluorescent microscopy showed RNA bound with nanoparticles within one hour at 24 ᵒC and were protected from degradation for > 14 days. qPCR assays showed that RNA-bound nanoparticles were released slowly over time. A greenhouse study using a completely randomized design was conducted twice to evaluate the impact of the nanoparticles on disease control. Escherichia coli hpRNA (300 ng/µl) containing the hpRNA of interest was combined with 0.2 mg/ml of the nanoparticles and sprayed on canola plants at flowering. One week later, agar plugs containing S. sclerotiorum hyphae were inoculated on plant stems. Lesion lengths were measured seven days later. The LDH-RNA and Si-RNA mixtures reduced disease severity significantly (P=0.05) compared to the control and hpRNA alone. These results showed that nanoparticles can increase RNA stability and efficacy.