Soilborne diseases continue to haunt farmers, quietly damaging roots and yields across countless crops. Traditional solutions like fungicides and crop rotation often come with ecological costs or limited effectiveness. Scientists are now turning to the plants themselves for help—specifically, to their ability to communicate with microbes in the soil via chemical signals. When stressed by the environment, plants release specialized metabolites into the soil that can summon microbial allies. These stress-induced “cries for help” are attracting increasing attention. Due to these challenges, there is a growing need to understand how environmental signals like light can rewire these plant–microbe interactions to suppress disease.
A team from Yunnan Agricultural University has discovered that manipulating light stress can activate a powerful defense mechanism in Panax notoginseng. Published (DOI: 10.1093/hr/uhae213) July 30, 2024, in Horticulture Research, the study shows that both low and high light exposure prompt ginseng roots to secrete flavonoids that suppress soilborne pathogens and nurture beneficial microbes. The findings suggest that light—typically managed for plant growth—can also be wielded to shape healthier soils and reduce plant disease without chemicals.
Through carefully controlled greenhouse and forest experiments, researchers exposed P. notoginseng to varying light intensities—optimal, low, and high—and tracked changes in root rot incidence and soil microbes. They found that both low and high light stress triggered the plant to boost its production of flavonoids, which significantly reshaped the rhizosphere microbiome. In these conditions, harmful Ilyonectria destructans pathogens declined, while friendly bacteria like Paenibacillus, Pseudomonas, and Arthrobacter flourished. Laboratory tests confirmed that these microbes not only thrived on the plant’s flavonoid exudates but also actively inhibited the pathogen. Soil from stressed-light conditions continued to benefit new plantings—unless sterilized—proving that the microbiome, not just the nutrients, carried the protective power. This dynamic interplay between light, root chemistry, and microbial allies paints a vivid picture of how plants turn environmental stress into ecological strength.
“This research flips the script on stress—it’s not something to avoid, but something we can strategically use,” said Professor Min Yang, co-corresponding author of the study. “By adjusting something as simple as light, we can help plants build their own microbial shield underground. It’s a natural, sustainable way to fight disease, and it may be especially valuable for vulnerable crops like medicinal ginseng.”
These findings offer a novel and practical strategy for disease management in agriculture. By tailoring light conditions—through greenhouse design, forest cultivation, or even canopy shading—growers can encourage plants to secrete beneficial flavonoids and reshape their microbiomes. This method holds particular promise for high-value, disease-prone crops like P. notoginseng. It also aligns with sustainable agriculture goals by reducing reliance on chemical pesticides and tapping into the plant’s innate ability to engineer its own soil environment. In the future, light modulation may become a key tool in precision farming, linking aboveground management to underground immunity.
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References
DOI
10.1093/hr/uhae213
Original Source URL
https://doi.org/10.1093/hr/uhae213
Funding information
This study was financially supported by the Natural Science Foundation of China (U23A20202), the Major Science and Technology Project in Yunnan Province (202102AE090042), and the Major Science and Technology Project of Kunming (2021JH002).
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.