Tea plants use sakuranetin as a natural antifungal shield against anthracnose, offering hope for greener farming Tea, one of the world's most cherished beverages, may have a powerful natural defense system hidden within its leaves
Scientists from the Zhejiang Academy of Agricultural Sciences have uncovered a molecular mechanism that enables certain tea plants to resist anthracnose—a destructive fungal disease that causes significant losses in tea plantations worldwide.
Their research reveals that a naturally occurring compound called sakuranetin (SAK) acts as a potent antifungal shield, helping resistant tea varieties stop infections before they spread.
The findings, published in Horticulture Research, provide fresh insights into how tea plants defend themselves and could open new avenues for sustainable tea cultivation.
Understanding Tea Plant Resistance
Anthracnose, caused by the fungus Colletotrichum camelliae, is among the most damaging diseases affecting tea crops. The pathogen spreads through wind and rain, infecting leaves and reducing both yield and quality.
Current control methods rely heavily on synthetic fungicides, raising concerns about environmental impact and chemical residues in a beverage consumed globally as a direct infusion.
Although tea plants naturally produce defensive compounds such as catechins and caffeine, researchers wanted to understand how the plant activates additional defenses after a fungal attack.
To investigate, the team compared two tea cultivars with contrasting disease responses: 'Zijuan', which is naturally resistant to anthracnose, and 'Longjing43', a widely cultivated but more susceptible variety.
The Science Behind Sakuranetin
The researchers discovered that when C. camelliae attacks, the resistant cultivar 'Zijuan' rapidly produces high levels of sakuranetin, a plant defense molecule known as a phytoalexin. This compound creates a hostile environment for the fungus, significantly restricting its growth.
Laboratory tests revealed that sakuranetin displayed stronger antifungal activity against C. camelliae than epigallocatechin gallate (EGCG), one of tea's most abundant and well-known catechins.
The key to this defense lies in an enzyme called naringenin 7-O-methyltransferase (NOMT), produced by the CsNOMT gene. The enzyme converts a flavonoid precursor, naringenin, into sakuranetin, effectively equipping the plant with a powerful chemical weapon.
Researchers observed that infected 'Zijuan' leaves accumulated substantial amounts of sakuranetin, whereas the susceptible cultivar 'Longjing43' produced very little.
A Molecular Relay Activates the Defense
The study uncovered an intricate defense pathway controlled by the plant hormone jasmonic acid (JA), a key regulator of immune responses in plants.
When the fungus invades, JA signaling becomes activated. This, in turn, stimulates a transcription factor called CsMYC2.1, which binds directly to the promoter region of the CsNOMT gene and switches it on.
Once activated, CsNOMT boosts sakuranetin production, creating a rapid chemical barrier against fungal invasion.
Researchers describe this process as a molecular relay:
Pathogen attack → JA signaling → CsMYC2.1 activation → CsNOMT expression → Sakuranetin production → Antifungal defense
This cascade was considerably stronger in 'Zijuan' than in 'Longjing43', explaining why the resistant cultivar is better protected from anthracnose.
Experiments Confirm the Protective Role
To confirm the importance of this pathway, scientists altered the expression of the CsNOMT gene.
When CsNOMT was silenced, sakuranetin levels dropped and plants became more vulnerable to anthracnose infection. Conversely, increasing CsNOMT expression elevated sakuranetin production and significantly reduced disease symptoms.
These experiments demonstrated that disease resistance is not determined by the presence of a single gene alone, but by how efficiently the plant activates its entire defense network when challenged by a pathogen.
Implications for Sustainable Tea Farming
The discovery has important implications for the future of tea cultivation.
The genes CsNOMT and CsMYC2.1 could serve as molecular markers, allowing breeders to identify and develop anthracnose-resistant tea varieties more quickly through marker-assisted breeding.
In addition, sakuranetin itself may provide a blueprint for developing natural biopesticides or plant defense stimulants that reduce reliance on synthetic fungicides.
Such approaches could help tea growers improve crop resilience while addressing growing concerns over environmental sustainability and chemical residues.
Beyond Tea: A Broader View of Plant Immunity
The findings also broaden scientists' understanding of plant immunity. While phytoalexin-based defenses have been extensively studied in crops such as rice and model plants, this research demonstrates that woody perennial crops like tea also rely on inducible chemical defenses to combat disease.
By linking hormone signaling, gene regulation, metabolite production, and disease resistance into a single framework, the study offers one of the clearest pictures yet of how tea plants mount a sophisticated defense against fungal attack.
For tea lovers around the world, this hidden molecular shield may one day help ensure healthier crops, more sustainable farming practices, and a more resilient future for one of the world's most beloved beverages.
Ref : JA–CsMYC2.1–CsNOMT–sakuranetin module contributes to differential anthracnose resistance in Camellia sinensis - (https://academic.oup.com/hr/article/13/5/uhag022/8444634?login=false)
https://en.wikipedia.org/wiki/Sakuranetin
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