Novel fungicide from rhizosphere streptomyces targeting filamentous fungal pathogens
Two Streptomyces strains isolated from soybean rhizosphere produce antifungal compounds selectively active against filamentous fungal pathogens (Fusarium, Rhizoctonia, Colletotrichum, Diaporthe, Macrophomina) but not against yeast-like fungi. The strains show biocontrol potential in soybean, are compatible with Bradyrhizobium japonicum inoculants, and improve plant growth and yield. Ongoing work focuses on purifying and characterizing the novel antifungal molecule.
Overview
This research presents a novel biocontrol approach based on two Streptomyces strains isolated from the soybean rhizosphere that produce antifungal compounds with selective activity against filamentous fungal pathogens. Unlike conventional fungicides, these compounds do not affect yeast-like fungi such as Saccharomyces cerevisiae, suggesting a new mechanism of action. The strains have demonstrated significant reduction of Macrophomina phaseolina and Diaporthe aspalathi infections in soybean under greenhouse and field conditions, while also being compatible with Bradyrhizobium japonicum, a standard soybean inoculant. Beyond pathogen control, the strains promote plant growth and development, translating into measurable yield improvements.
Technical specifications
Target pathogens:
- Fusarium tucumaniae
- Fusarium verticillioides
- Rhizoctonia solani
- Colletotrichum graminicola
- Diaporthe aspalathi
- Macrophomina phaseolina
Key features:
- Selective antifungal activity against filamentous fungi without affecting yeast-like organisms
- Compatibility with B. japonicum soybean inoculants, enabling integrated crop protection strategies
- Plant growth promotion effects in addition to biocontrol activity
- Validated efficacy in soybean seed treatment with liquid formulation
- Genome sequencing underway to identify the fungicidal gene cluster
Planned characterization approach:
- Bioguided fractionation of culture supernatants, bacterial pellets, and solvent extracts
- Purification via silica gel chromatography, size exclusion chromatography, ion exchange, or HPLC
- Molecular characterization using LC-MS and NMR
- Bioinformatics analysis of the genome to identify the biosynthetic gene cluster
- Comparison with natural product databases to confirm novelty
Technology readiness level
The technology is currently at an advanced research and early validation stage. Two Streptomyces strains have been isolated and confirmed to produce selective antifungal compounds in vitro. Greenhouse and field trials in soybean have demonstrated significant reductions in Macrophomina phaseolina and Diaporthe aspalathi infection, along with positive effects on plant growth and yield. The next phase involves scaling up fermentation, purifying the active compound through bioguided approaches, and characterizing its chemical structure and biosynthetic gene cluster to confirm novelty and elucidate the mode of action.
About Instituto de Biología Molecular y Celular de Rosario
IBR is a public research institute jointly operated by CONICET and the National University of Rosario, with more than 240 researchers, staff, and trainees across two sites: the CONICET CCT‑Rosario campus and a facility within UNR’s Faculty of Biochemical and Pharmaceutical Sciences. For industry, the institute offers co‑located laboratories, shared instrumentation, BSL‑2/3 suites, an NMR annex, and open service platforms run by expert staff; these resources are used by more than 40 SMEs and large companies. Startup formation is supported by Bio.R, an on‑site accelerator and incubation space adjacent to the main building, complemented by a dedicated foundation that promotes transfer to the productive sector. Research is principally supported by Argentina’s national science system through CONICET and competitive programs, with international collaborations that comply with NIH Financial Conflict of Interest guidelines.
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