Metabolic Bioproducts of Soil Streptomycetes and Their Effect on RNAi-Mediated Resistance of Tomato Plants Against Root-Knot Nematode Meloidogyne Incognita

Streptomyces species are renowned for producing bioactive natural products, particularly those that induce plant resistance against pathogens and nematodes. This study aimed to investigate the ability of metabolic bioproducts from Streptomyces netropsis IMV Ac-5025, Streptomyces violaceus IMV Ac-5027, and Streptomyces avermitilis IMV Ac-5015 to affect RNAi-mediated resistance in tomato plants against the root-knot nematode.

Spectrodensitometric Thin-Layer Chromatography (TLC), High-Performance Liquid Chromatography (HPLC), and Gas Chromatography (GC) were used to identify natural products of streptomycetes. The resistance of tomato plants to Meloidogyne incognita was evaluated through artificial nematode inoculation coupled with phenological viability assessment. The extent of si/miRNA-driven gene silencing was determined via dot blot hybridization and inhibition of protein synthesis in a wheat germ cell-free translation system.

Soil-derived Streptomyces strains were shown to produce diverse bioactive compounds, including antibiotics, lipids, phytohormones, and sterols, and novel bioproducts were developed based on their secondary metabolites (Phytovit, Violar, Averkom, and Averkom nova). Incorporation of these bioproducts into the nutrient medium significantly improved shoot regeneration rates in isolated plant explants. Dot blot hybridization and translational inhibition assays in a wheat germ cell-free system confirmed their phytoprotective effect via the RNA interference mechanism. In vitro cultivation of tomato plants supplemented with biotreatment resulted in a marked enhancement of resistance to M. incognita.

The secondary metabolic complexes produced by Streptomyces strains promote plant growth and development while enhancing immunity and supporting the efficient operation of signaling networks involved in cellular responses to nematodes. Their activity is mediated through elicitor signals that trigger the de novo synthesis of plant si/miRNAs, which confer protection against M. incognita. These findings highlight the potential of these metabolites to advance eco-friendly strategies for controlling root-knot nematodes and to develop resistant plant lines.

Soil-streptomycete metabolites could be utilized in RNA interference to enhance tomato resistance to root-knot nematodes via de novo synthesis of protective small interfering and microRNAs, supporting agrobiological applications.