Wenbo Yang

(1) Background: In recent years, new pests have been constantly emerging in tea trees, posing a significant threat to tea production. Therefore, it is necessary to monitor and investigate whether new pests have emerged in tea trees. (2) Methods: A new tea pest discovered in a tea garden was identified through mitochondrial cytochrome-c oxidase subunit I (COI) gene sequence analysis and observation of morphological characteristics. Its occurrence pattern was also analyzed in detail, and preliminary control methods were proposed. (3) Results: During the 2023 tea garden pest investigation, we discovered a new tea pest for the first time in a tea garden in Jiepai Town, Hengyang County, Hengyang City, Hunan Province, and identified it as Nysius ericae (Schilling). The results indicated that N. ericae was mainly fed on the upper leaves of tea trees, and high temperature and drought were suitable for its occurrence. Furthermore, various concentrations (1~16 mg/L) of matrine showed significant toxicity against N. ericae under laboratory conditions. (4) Conclusions: Our research has discovered for the first time a new pest of tea trees, providing an important scientific foundation for the monitoring, early warning, and prevention and control of N. ericae in tea gardens, which is of great significance for ensuring the ecological security and tea quality of tea gardens.

The promising biocontrol agent Brevibacillus brevis is a broadly dispersed bacterium exhibiting significant antibacterial properties against plant diseases. This study conducted a comprehensive comparative genomic analysis of 25 B. brevis strains to examine their taxonomic classification, genetic diversity, and biocontrol potential. The genome sizes, excluding strain NEB573, varied from 5.95 to 6.73 Mb, with GC content between 47.0% and 47.5%. Notably, strain NEB573 exhibited distinct genomic characteristics based on Average Nucleotide Identity (ANI), digital DNA-DNA hybridisation (dDDH), and phylogenetic analyses, suggesting it may represent a novel Brevibacillus species pending additional phenotypic confirmation. The remaining 24 strains were grouped into six phylogenetic clades. The pan-genome study demonstrated significant genomic flexibility, demonstrating an open architecture with 2855 core gene families (33.08%) and 1699 distinct genes. Functional annotations indicated that unique genes were enriched in tasks related to DNA repair and environmental adaptation, while core genes predominantly participated in amino acid metabolism and transcription. The examination of biosynthetic gene clusters (BGCs) identified multiple antimicrobial compounds, such as gramicidin and tyrocidine, which have been reported to exhibit both antibacterial and antifungal activities, thereby underscoring the broad-spectrum biocontrol potential of B. brevis. These findings endorse the application of biocontrol in sustainable plant disease management and offer novel perspectives on its genetic basis in B. brevis. Future investigations of its metabolic repertoire may unveil novel agro-biotechnological applications.

Theanine is a crucial indicator of tea quality, its significance is closely tied to the economic value of tea. There were many reports on the regulation mechanism of theanine synthesis and accumulation, but the mechanism of gibberellin regulates theanine synthesis in tea plants is poorly understood. Previous studies have shown that the content of theanine experiences significant changed in the growth stages of tea shoots, displayed a strong correlation with gibberellin. This study confirmed that gibberellin significantly promoted the expression of the major gene of theanine synthesis, known as CsTSI. Additionally, the study identified CsWRKY71, a transcription factor mediated the regulation of gibberellin on theanine synthesis in tea plants. CsWRKY71 was localized in the nucleus and had a typical WRKY domain. It was a member of class IIC sub- and its expression was significantly suppressed following exogenous GA₃ treatment. Further assay such as EMSA, dual luciferase and asODN interfering demonstrated that CsWRKY71 significantly interacted with the promoter of CsTSI, which inhibited theanine synthesis by binding to the cis-acting element (C/T)TGAC(T/C) of CsTSI promoter. Overall, the addition of exogenous gibberellin alleviated the inhibition of CsTSI by down-regulating the expression of CsWRKY71, ultimately facilitated the rapid biosynthesis of theanine. This study elucidated the molecular mechanism of CsWRKY71 mediated gibberellin regulation of theanine synthesis in tea plant. The findings not only enhance our understanding of the regulatory processes involved in theanine synthesis in tea plants, but also provide important references for maintaining the characteristics of high theanine in tea plant.