Natural Soil Fungi Help Watermelon Plants Fight Disease and Improve Soil Health

Jim Crocker
24th June, 2024

Natural Soil Fungi Help Watermelon Plants Fight Disease and Improve Soil Health

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Qingdao Agricultural University found that certain root exudates from mycorrhizal watermelon plants can reduce fusarium wilt
  • The fungi Funneliformis mosseae and Glomus versiforme secrete compounds diisooctyl phthalate and dibutyl phthalate, which help mitigate the disease
  • These compounds also improve plant health by altering the microbial community in the soil, increasing beneficial bacteria and reducing harmful ones
Fusarium wilt is a persistent and destructive disease affecting watermelon crops, significantly reducing their productivity. Continuous cropping, a practice where the same crop is grown repeatedly on the same land, exacerbates this issue. Recent research conducted by Qingdao Agricultural University has identified potential solutions by examining how certain root exudates from mycorrhizal watermelon plants can mitigate this problem[1]. The study focused on mycorrhizal fungi, specifically Funneliformis mosseae and Glomus versiforme, which form symbiotic relationships with plant roots. These fungi were found to secrete specific compounds, namely diisooctyl phthalate (A) and dibutyl phthalate (B), into the soil. The presence of these compounds was linked to a significant reduction in fusarium wilt incidence and an improvement in overall plant health. The researchers tested varying concentrations of these compounds (0.1 ml/L, 0.5 ml/L, and 1 ml/L) and observed their effects on soil enzyme activities, microbial populations, and disease incidence. Notably, the disease indexes (DI) for the lowest concentration of diisooctyl phthalate (A1) and the highest concentration of dibutyl phthalate (B3) were 25% and 20%, respectively. The prevention and control effects (PCE) were 68.8% and 75%, respectively, indicating substantial disease mitigation. These findings align with earlier research demonstrating that plant genotype and associated microbial communities significantly influence resistance to Fusarium oxysporum, the pathogen responsible for fusarium wilt[2]. The study showed that resistant watermelon cultivars had more abundant populations of beneficial bacteria and actinomycetes compared to susceptible ones, while the presence of harmful fungi was lower. Further supporting the current study, previous research has highlighted the role of arbuscular mycorrhizal fungi (AMF) in inhibiting the growth of Fusarium species and reducing mycotoxin production[3]. This biological control method offers a promising alternative to chemical treatments, which often lead to resistance issues. Interestingly, the current study also found that diisooctyl phthalate and dibutyl phthalate altered the microbial community structure in the rhizosphere, the soil region near the plant roots. These compounds increased the proportions of beneficial bacterial groups such as Gemmatimonadetes, Chloroflexi, and Acidobacteria, while reducing the proportions of potentially harmful groups like Proteobacteria and Firmicutes. This shift in microbial balance likely contributes to the enhanced resistance observed in the treated plants. Moreover, the study revealed that these phthalates promoted various growth parameters of watermelon plants, including vine length, stem diameter, and both fresh and dry weight. They also boosted the activities of antioxidant enzymes (SOD, POD, and CAT), which are crucial for plant stress responses. The presence of phthalates in agricultural settings is not without controversy, as these compounds are often associated with plastic pollution and potential health risks[4][5]. However, this study suggests that at specific concentrations, diisooctyl phthalate and dibutyl phthalate can play a beneficial role in agricultural practices by alleviating continuous cropping disorders and reducing disease incidence. In conclusion, the research from Qingdao Agricultural University provides compelling evidence that certain root exudates from mycorrhizal watermelon can significantly reduce the incidence of fusarium wilt and improve plant growth. This study builds on previous findings[2][3] and offers a novel approach to managing soil-borne diseases in continuous cropping systems. The use of phthalates, while typically seen in a negative light, shows potential for agricultural benefits when applied in controlled concentrations.

BiochemPlant ScienceMycology

References

Main Study

1) Arbuscular mycorrhizal fungi by inducing watermelon roots secretion phthalates, altering soil enzyme activity and bacterial community composition to alleviate the watermelon wilt.

Published 24th June, 2024

https://doi.org/10.1186/s12870-024-05254-7

Related Studies

2) Rhizosphere soil microorganism populations and community structures of different watermelon cultivars with differing resistance to Fusarium oxysporum f. sp. niveum.

Journal: Canadian journal of microbiology, Issue: Vol 57, Issue 5, May 2011

3) The arbuscular mycorrhizal fungus, Glomus irregulare, controls the mycotoxin production of Fusarium sambucinum in the pathogenesis of potato.

https://doi.org/10.1111/1574-6968.12236

4) Presence, distribution and risk assessment of phthalic acid esters (PAEs) in suburban plastic film pepper-growing greenhouses with different service life.

https://doi.org/10.1016/j.ecoenv.2020.110551

5) Phthalates contamination in China: Status, trends and human exposure-with an emphasis on oral intake.

https://doi.org/10.1016/j.envpol.2018.02.088


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