Researchers Uncover Key Defenses in Tea Plants Against Insect Herbivores
In a significant advancement for agricultural science, researchers from the Tea Research Institute at the Chinese Academy of Agricultural Sciences have identified two critical receptors in tea plants that play a vital role in defending against insect herbivores. This study, published on October 2, 2024, in the journal Horticulture Research, sheds light on how tea plants recognize and respond to damage from pests, particularly the tea geometrid caterpillar.
Insect herbivores present a major threat to crop production worldwide. Plants detect these threats through specific molecules associated with damage, which activate early defense mechanisms. While prior research has established the role of leucine-rich repeat receptor-like kinases (LRR-RLKs) in grasses such as rice and maize, their function in woody plants like tea remained largely unexplored. This study marks a pivotal step in understanding these receptors’ roles in tree species.
The researchers conducted a comprehensive analysis of the tea plant genome, identifying 307 full-length LRR-RLK genes distributed across 15 chromosomes. Among these, two receptors—CsLRR-RLK44 and CsLRR-RLK239—were found to be significantly induced during caterpillar feeding. These receptors were rapidly upregulated in response to herbivory and correlated negatively with larval growth, suggesting they play a protective role against pest attacks.
The study used gene-silencing experiments to validate the importance of these receptors. Silencing either receptor led to increased weight gain in caterpillars, further underscoring their critical role in plant defense. Additionally, the research demonstrated that silencing these receptors impaired the expression of downstream signaling components, such as CsMEKK20 and CsMPK3, and disrupted the activation of essential WRKY transcription factors involved in defense responses.
The findings revealed that both receptors are located on the plasma membrane, consistent with their function as receptors. Importantly, suppression of CsLRR-RLK44 or CsLRR-RLK239 decreased the accumulation of jasmonates—key signaling molecules in plant defense—and reduced the expression of jasmonate biosynthesis genes like CsLOX7 and CsAOS. This establishes a conserved defense pathway involving mitogen-activated protein kinase cascades and jasmonate signaling that is vital for the tea plant’s ability to fend off herbivory.
Co-corresponding author Dr. Jianyan Huang emphasized the significance of this research, stating, “Our work demonstrates for the first time that specific LRR-RLKs in woody plants are central to initiating insect defense responses.” The identification of these receptors not only enhances our understanding of tea plants but also offers valuable genetic targets for improving resistance against pests. This could greatly benefit tea cultivation by reducing dependency on pesticides and promoting sustainable practices.
The implications of this research extend beyond tea plants. By understanding how woody crops recognize and respond to herbivores, similar strategies can be developed for other perennial crops and trees. This knowledge lays the groundwork for innovative agricultural practices that aim to secure productivity in environments increasingly challenged by pests.
Funding for this research was provided by the National Natural Science Foundation of China, the Central Public-interest Scientific Institution Basal Research Fund, and the Zhejiang Science and Technology Major Program on Agricultural New Variety Breeding.
As the agricultural sector faces mounting pressures from pests, the insights gained from this study will be crucial for developing resilient crops capable of withstanding biotic stressors and ensuring sustainable food production.
