Leaf chemistry and microbes combine to boost disease resistance in black currants
image: Image caption: The mechanism of resistant cultivar enhances resistance to PM pathogens in the black currant phyllosphere. Image link: https://academic.oup.com/view-large/figure/521283597/uhaf092f8.tif
Credit: Horticulture Research
Powdery mildew is one of the most destructive fungal diseases affecting black currants, infecting leaves, stems, and young fruits while reducing yield and fruit quality. Chemical pesticides provide short-term control but raise environmental and health concerns, underscoring the need for sustainable disease-resistant strategies. Increasing evidence shows that plants rely not only on genetic defenses but also on interactions with microorganisms living on their surfaces and on metabolite-mediated signaling. Yet the mechanisms by which leaf-surface metabolites shape the phyllosphere microbiome to enhance resistance remain poorly understood. Due to these challenges, there is a need to conduct in-depth research into metabolite–microbiome interactions in disease-resistant and susceptible cultivars.
Researchers from Northeast Agricultural University reported a comprehensive analysis of phyllosphere metabolites and microbial communities in resistant and susceptible black currant cultivars. The study, published (DOI: 10.1093/hr/uhaf092) on 25 March 2025 in Horticulture Research, used high-throughput sequencing and metabolomic profiling to uncover how resistant plants coordinate metabolic and microbial responses following powdery mildew infection. The team demonstrated that specific metabolites promote the enrichment of beneficial microbial taxa and suppress fungal growth, offering new insights into natural disease resistance mechanisms.
The researchers compared a resistant cultivar (“16A”) and a susceptible cultivar (“Bright leaf”) to investigate how leaf structures, metabolites, and phyllosphere microbiota respond to powdery mildew infection. Resistant plants exhibited thicker leaf tissues and fewer stomata, forming inherent physical barriers that reduced pathogen entry. Metabolomic analysis identified 534 differentially accumulated metabolites, with resistant plants showing elevated levels of salicylic acid, trans-zeatin, and griseofulvin—metabolites previously linked to disease responses. Network analysis of microbial communities revealed significantly higher bacterial and fungal diversity in the resistant cultivar, along with greater fungal network complexity. Keystone microbes associated with resistance included Bacillus, Burkholderia, and Penicillium, all known for antagonistic or protective functions.
Correlation analyses showed that key metabolites strongly influenced beneficial microbial groups, acting as biochemical cues that recruit “disease resistance effectors” in both bacteria and fungi. Functional predictions further indicated enhanced pathways related to environmental adaptation and signal transduction in the resistant cultivar. Experimental validation demonstrated that spraying griseofulvin, salicylic acid, or trans-zeatin on susceptible plants reduced disease severity, with 150 mg/L griseofulvin showing the strongest inhibitory effect on fungal development and spore cycling. These findings collectively reveal an integrated, metabolite-driven microbiome strategy underlying disease resistance.
“The study shows that resistant black currant cultivars do not rely on a single defense mechanism. Instead, they coordinate structural traits, metabolite production, and microbial recruitment to limit powdery mildew development,” the researchers explained. They emphasized that metabolites such as salicylic acid, trans-zeatin, and griseofulvin serve as critical regulators linking plant physiology with microbial community assembly. “Understanding these multilayered interactions provides a foundation for developing sustainable disease-management strategies and improving crop resilience through breeding and microbiome engineering.”
This work highlights practical opportunities for enhancing disease resistance in horticultural crops. The identified metabolites may serve as biomarkers for screening elite germplasm, while microbial keystones such as Bacillus, Burkholderia, and Penicillium could inform the development of microbial inoculants or phyllosphere-targeted biocontrol agents. The demonstrated efficacy of metabolite treatments, particularly griseofulvin, suggests potential for integrating natural metabolites into low-input plant protection strategies. More broadly, the study underscores the value of metabolite-mediated microbiome engineering for reducing dependence on chemical pesticides and advancing sustainable fruit production systems.
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References
DOI
Original Source URl
https://doi.org/10.1093/hr/uhaf092
Funding information
This research was funded by ‘14th Five-Year Plan’ National Key Research and Development Program Project ‘Research and Application Demonstration of Key Technologies of Fruit Industry in Cold Areas’ (No. 2022YFD1600500).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.