RNAi-Based Biocontrol of Wheat Nematodes Using Natural Poly-Component Biostimulants

Abstract

With the growing global demands on sustainable food production, one of the biggest challenges to agriculture is associated with crop losses due to parasitic nematodes. While chemical pesticides have been quite successful in crop protection and mitigation of damage from parasites, their potential harm to humans and environment, as well as the emergence of nematode resistance, have necessitated the development of viable alternatives to chemical pesticides. One of the most promising and targeted approaches to biocontrol of parasitic nematodes in crops is that of RNA interference (RNAi). In this study we explore the possibility of using biostimulants obtained from metabolites of soil streptomycetes to protect wheat ( Triticum aestivum L.) against the cereal cyst nematode Heterodera avenae by means of inducing RNAi in wheat plants. Theoretical models of uptake of organic compounds by plants, and within-plant RNAi dynamics, have provided us with useful insights regarding the choice of routes for delivery of RNAi-inducing biostimulants into plants. We then conducted in planta experiments with several streptomycete-derived biostimulants, which have demonstrated the efficiency of these biostimulants at improving plant growth and development, as well as in providing resistance against the cereal cyst nematode. Using dot blot hybridization we demonstrate that biostimulants trigger a significant increase of the production in plant cells of si/miRNA complementary with plant and nematode mRNA. Wheat germ cell-free experiments show that these si/miRNAs are indeed very effective at silencing the translation of nematode mRNA having complementary sequences, thus reducing the level of nematode infestation and improving plant resistance to nematodes. Thus, we conclude that natural biostimulants produced from metabolites of soil streptomycetes provide an effective tool for biocontrol of wheat nematode.

Control of mosaic disease using microbial biostimulants: insights from mathematical modelling

“…Since the use of MBs largely relies on farmers' awareness about the mosaic disease, one can also consider how different types of disease awareness and corresponding use of MBs affect progression and control of mosaic disease, as has been recently explored in the context of using nutrients and insecticides [71]. It should be noted that there are different methods of applying MBs to plants, including soaking of seeds prior to sowing, applying them to the medium, in which the plants are growing, or spraying them directly on growing plants [52,54,64]. Each of these approaches has its own benefits and limitations in terms of costs, ease of implementation, and the efficiency of inducing within-plant production of relevant RNAi compounds.…”

“…Experimental evidence suggests that streptomycete-derived MBs stimulate growth and viability of crops, as has been recently demonstrated during in vitro, in vivo and greenhouse experiments on wheat [52,53,64], cucumbers [56], rapeseed [59], and Chinese cabbage [57]. Thus, we replace a constant growth rate of uninfected plants by a growing saturated function of the amount of applied MBs…”

Optimizing Safe Approaches to Manage Plant-Parasitic Nematodes

“…In planta wheat [84] Using various composts as big sources of soil amendments should be further exploited. They could be manipulated via fermentation processes to make them enriched in the desired microbial species and PPN antagonistic compounds, such as phenolics and humic acids [85].…”

Composted Municipal Green Waste Infused with Biocontrol Agents to Control Plant Parasitic Nematodes—A Review

“…One of the most promising and targeted approaches to the biocontrol of parasitic nematodes in crops is RNA interference [244]. In describing the strategy against the cereal cyst nematode Heterodera avenae by using RNAi-inducing streptomycete-derived biostimulants in Triticum aestivum L. plants, the authors demonstrate the synthesis of si/miRNAs within wheat cells and their silencing activity by dot blot hybridisation experiments, concluding that these biostimulants are able to reduce nematode infestation through plant-induced nematode mortality.…”

“…In describing the strategy against the cereal cyst nematode Heterodera avenae by using RNAi-inducing streptomycete-derived biostimulants in Triticum aestivum L. plants, the authors demonstrate the synthesis of si/miRNAs within wheat cells and their silencing activity by dot blot hybridisation experiments, concluding that these biostimulants are able to reduce nematode infestation through plant-induced nematode mortality. The most effective and direct way should be to select specific genes in the PPN that are silenced by si/miRNAs produced in host plants under the action of biostimulants [244,245]. This is to underscore what is increasingly emerging from the recent literature, namely that plant miRNAs can be exploited to inhibit pathogen development or aid mutualistic relationships.…”