DefinePK

Research Objective

To evaluate the capacity of culture filtrates and organic fractions of Aspergillus spp. to suppress the radial growth of Phytophthora erythroseptica and limit the severity of pink rot disease in potato tubers.

Methodology

The study involved isolating Aspergillus spp. from disease-suppressive soils and composts. Culture filtrates were prepared by growing these fungi in potato dextrose broth. Organic fractions (chloroform and ethyl acetate) were extracted from the most active filtrates. The efficacy of these filtrates and fractions was tested in vitro against Phytophthora erythroseptica radial growth and in vivo on inoculated potato tubers to assess disease severity. Statistical analysis was performed using SPSS.

Methodology Flowchart

                        graph TD
    A[Isolation of Aspergillus spp.] --> B[Preparation of Culture Filtrates];
    B --> C[Extraction of Organic Fractions];
    B --> D[In vitro Screening of Filtrates];
    C --> E[In vitro Screening of Organic Fractions];
    D --> F[In vivo Testing on Potato Tubers];
    E --> F;
    F --> G[Data Analysis];
    G --> H[Conclusion];                    

Discussion

The study highlights the potential of secondary metabolites from Aspergillus spp. as eco-friendly alternatives to chemical pesticides for controlling potato pink rot. The effectiveness of culture filtrates and organic fractions suggests the presence of bioactive compounds. The variation in inhibitory potential based on concentration and the specific fractions used indicates the complex nature of these metabolites. The findings align with previous research on the biocontrol capabilities of Aspergillus species against various plant pathogens.

Key Findings

Culture filtrates of Aspergillus spp. were most active at a 20% (v/v) concentration, with Aspergillus niger CH12 cell-free filtrates showing the maximum inhibition (32%) of Phytophthora erythroseptica. Chloroform and ethyl acetate fractions of filtrates from A. niger CH12, A. terreus CH2, A. terreus MC8, and Aspergillus sp. CH8, tested at 5% (v/v), reduced pathogen growth by up to 85%. Both original filtrates and organic fractions significantly reduced pink rot severity on inoculated potato tubers, with lesion diameter and penetration reduced by 30-85% and 55-93%, respectively. Organic fractions lowered disease severity by 78-90%.

Conclusion

Secondary metabolites from the tested Aspergillus spp. isolates are rich in bioactive compounds with significant potential to reduce potato pink rot disease severity. The study demonstrates the efficacy of both culture filtrates and organic extracts in controlling the pathogen both in vitro and in vivo, suggesting their promise for developing natural bio-fungicides.

Fact Check

1. Maximum inhibition of fungal pathogen: Aspergillus niger CH12 cell-free filtrates achieved a maximum inhibition of 32% of the fungal pathogen's growth.
2. Reduction in lesion diameter: Treatments with filtrates reduced lesion diameter by 30-85%.
3. Reduction in rot penetration: Treatments with filtrates reduced rot penetration by 55-93%.

Mind Map