Pepper root exudate attenuates snap bean root rot by mediating microbial community remodeling

Area of Science:

• Agricultural Science
• Plant Pathology
• Microbiology

Background:

• Root rot caused by *Fusarium solani* significantly threatens snap bean production and sustainable agriculture.
• Continuous cropping exacerbates soil-borne diseases, while chemical controls face limitations like pathogen resistance and environmental contamination.
• Intercropping snap beans with peppers can reduce root rot, but the underlying mechanisms of pepper's protective effect via root exudates are not fully understood.

Purpose of the Study:

• To investigate the disease-suppressive effects of exogenously applied pepper root exudates on snap bean root rot.
• To elucidate the mechanisms by which pepper root exudates modulate the snap bean rhizosphere microbial community and induce plant defense responses.
• To provide theoretical and practical guidance for developing biological agents for green agriculture and sustainable snap bean production.

Main Methods:

• Pot experiments were conducted to assess the effects of pepper root exudates on snap bean plants under pathogen stress.
• In vitro assays validated the biocontrol efficacy of antagonistic bacteria and the flavonoid Chrysin.
• High-throughput sequencing and untargeted metabolomics analyzed changes in rhizosphere microbial communities and root exudate profiles.

Main Results:

• Application of pepper root exudates significantly reduced *Fusarium solani* abundance and snap bean root rot symptoms.
• Exudates enhanced snap bean plant antioxidant enzyme activities.
• Rhizosphere microbial communities were restructured, enriching beneficial microbes like *Streptomyces* and enhancing microbial network stability.
• Pepper root exudates induced snap bean roots to secrete flavone compounds, such as Chrysin, which correlated positively with beneficial microbes and negatively with *Fusarium*.

Conclusions:

• Exogenous pepper root exudates mitigate snap bean root rot by remodeling the rhizosphere microbiome and promoting endogenous flavone synthesis.
• This study provides a foundation for eco-friendly vegetable disease management and advances sustainable agricultural practices.
• Pepper root exudates represent a promising strategy for enhancing snap bean resistance to root rot and contributing to green agriculture.