Isolation and Characterization of a Cold-Tolerant Strain of Fusarium proliferatum, a Biocontrol Agent of Grape Downy Mildew
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Abstract:
ABSTRACT A cold-tolerant strain of the mycoparasite Fusarium proliferatum was isolated following UV mutagenesis of the G6 strain, which is a biocontrol agent of grape downy mildew. The isolated strain (designated 1505) exhibited radial growth two to threefold that of the parent strain when grown at 13 degrees C, which is generally suboptimal for growth of Fusarium spp., but desirable for its host, Plasmopara viticola. This rapid growth was correlated with improved biological control of P. viticola, determined by a detached-leaf assay. Even though radial growth of strain 1505 at higher temperatures was slower than that of G6 and the strain failed to conidiate, there was no reduction in biocontrol efficacy. Significantly higher levels of extracellular beta-glucosidase and endo-1,4-beta-glucanase activity were measured in the culture filtrate of strain 1505 relative to that of strain G6. A DNA-mediated transformation procedure that included the introduction of antibiotic resistance and a GUS reporter gene system was adapted for F. proliferatum. Using the GUS-engineered strains, we demonstrated that both G6 and 1505 exhibit the characteristic coiling and penetration of host structures.
Insights
A new cold-tolerant strain of Fusarium proliferatum (1505) enhances biocontrol of grape downy mildew. This strain shows improved growth at low temperatures and increased enzyme activity, boosting efficacy against Plasmopara viticola.
Area of Science:
- Mycology
- Plant Pathology
- Biotechnology
Background:
- Fusarium proliferatum is a mycoparasite used for biocontrol.
- Grape downy mildew, caused by Plasmopara viticola, is a significant agricultural concern.
- Optimizing biocontrol agents for specific environmental conditions is crucial for effective disease management.
Purpose of the Study:
- To develop a cold-tolerant strain of Fusarium proliferatum for improved biocontrol of grape downy mildew.
- To investigate the growth characteristics and biocontrol efficacy of the new strain at suboptimal temperatures.
- To analyze the enzymatic activity and genetic modification potential of the enhanced strain.
Main Methods:
- UV mutagenesis was used to generate a cold-tolerant strain (1505) from a parent biocontrol strain (G6).
- Radial growth was measured at 13°C and higher temperatures.
- Detached-leaf assays were performed to assess biocontrol efficacy against Plasmopara viticola.
- Extracellular enzyme activity (beta-glucosidase, endo-1,4-beta-glucanase) was quantified.
- DNA-mediated transformation with antibiotic resistance and GUS reporter genes was adapted for F. proliferatum.
Main Results:
- Strain 1505 showed a two-to-threefold increase in radial growth at 13°C compared to the parent strain G6.
- Improved biological control of P. viticola was observed with strain 1505.
- Strain 1505 exhibited significantly higher extracellular beta-glucosidase and endo-1,4-beta-glucanase activity.
- Despite slower growth and lack of conidiation at higher temperatures, strain 1505 maintained biocontrol efficacy.
- GUS-engineered strains confirmed characteristic host coiling and penetration by both G6 and 1505.
Conclusions:
- The cold-tolerant strain 1505 of Fusarium proliferatum offers enhanced biocontrol of grape downy mildew, particularly under cooler conditions.
- Increased enzymatic activity in strain 1505 contributes to its improved mycoparasitic capabilities.
- The adapted transformation procedure facilitates genetic engineering of F. proliferatum for further research and application.
