Genetic study reveals why some tea plants are more vulnerable to insects

Tea (Camellia sinensis) is one of the world’s most consumed beverages, but its production faces constant threats from pests and diseases. Plant defense hormones such as SA and ABA orchestrate complex immune networks that determine crop resilience. Although SA is known to enhance resistance against biotrophic pathogens, its molecular regulation in tea remains poorly defined. Moreover, antagonistic interactions between SA and ABA complicate plant responses to infection, potentially influencing pest susceptibility. Due to these unresolved mechanisms, it is necessary to investigate how genetic variation regulates SA biosynthesis and signaling pathways in tea plants.

A research team from Guizhou University and North China University of Science and Technology has conducted a comprehensive GWAS on tea plants, published (DOI: 10.1093/hr/uhae362) on April 1, 2025, in Horticulture Research. By examining 79,560 high-quality single nucleotide polymorphisms (SNPs) from 299 tea accessions, the study identified CsNCED1, a key gene controlling the antagonism between SA and ABA. The gene was shown to suppress SA accumulation and increase plant vulnerability to pest attacks, providing a foundation for selective breeding of disease- and insect-resistant tea varieties.

Using GBS and GWAS, the researchers evaluated SA content across 299 tea germplasms collected from Guizhou, revealing broad natural variation under two environmental conditions. Population structure and linkage disequilibrium analyses classified the accessions into five genetic subgroups. The team pinpointed 28 significant SNPs associated with SA levels, of which CsNCED1—encoding a 9-cis-epoxycarotenoid dioxygenase—emerged as the leading candidate. This enzyme catalyzes a key step in ABA biosynthesis, linking hormone metabolism with immunity.

Functional assays confirmed that exogenous ABA treatment reduced SA accumulation by downregulating the SA biosynthetic gene ICS and the receptor gene NPR1, along with its downstream targets PR1 and WRKY18. Transgenic tobacco plants overexpressing CsNCED1 exhibited higher ABA levels, lower SA concentrations, and larger insect feeding areas than wild-type plants. These results demonstrated that CsNCED1 acts as a negative regulator of SA-mediated immune responses, offering genetic targets for improving pest resistance in tea breeding programs.

“Tea plants rely on a delicate hormonal balance to defend themselves,” said Prof. Suzhen Niu, corresponding author of the study. “Our findings highlight that excessive activation of the ABA pathway can suppress salicylic acid defenses, making plants more vulnerable to insects and pathogens. Understanding this antagonism allows us to design molecular breeding strategies that restore this balance—enhancing natural resistance while reducing pesticide reliance.”

This study provides a genetic framework for understanding hormone crosstalk in tea immunity. By identifying CsNCED1 as a key suppressor of salicylic acid signaling, researchers now have a molecular handle for developing insect-resistant tea cultivars through marker-assisted selection (MAS). The findings also open possibilities for precision breeding aimed at optimizing hormone homeostasis to improve resilience under biotic stress. Ultimately, this research not only supports sustainable tea production but also offers a model for studying stress-regulatory mechanisms in other perennial crops.

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References

DOI

10.1093/hr/uhae362

Original Source URL

https://doi.org/10.1093/hr/uhae362

Funding information

This study was supported by the program of NSFC [32060700], the National Guidance Foundation for Local Science and Technology Development of China [[2023] 009] and [2022-1-52], Guiyang Science and Technology Plan Project [Construction Technology Contract [2023] 48–21], the Science and Technology Project of Guizhou Province, China (Qiankehe Foundation-ZK [2022]) (Grant No.702076222101).

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, 2024. 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.