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.

As a biocontrol bacteria, Brevibacillus has been the subject of extensive research for agricultural applications. Antibacterial peptides (AMPs) are the main antibacterial products of Brevibacillus. This study isolated a strain of Br. brevis HNCS-1 from tea garden soil, and the strain has an antagonistic effect against five types of pathogens of tea diseases, namely Gloeosporium theae-sinensis, Elsinoe leucospira, Phyllosticta theaefolia, Fusarium sp., and Cercospora theae. To determine the genetic characteristics implicated in the biocontrol mechanism, the genome sequence of the HNCS-1 strain was obtained and analyzed further, and the data are deposited in the GenBank repository (No. CP128411). Comparative genomics analyses revealed that the HNCS-1 strain and 17 public Br. brevis share a core genome composed of 3,742 genes. Interestingly, only one non-ribosomal peptide synthetase (NRPS) gene cluster annotated as edeine is present in the core genome. And UHPLC-MS/MS detection results showd that edeine B and edeine A were the principal antibacterial peptides in the HNCS-1 strain. This study proves that edeine is the main antibacterial peptide of Br. brevis, and provides a new strategy for the identification of antibacterial products from other biocontrol bacteria.

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.

Nitrogen is an important nutrient for the tea plant (Camellia sinensis), which profoundly affects the quality and value of tea. In this study, the variations of biochemical activities, antioxidant systems, and tea quality of two tea varieties under four levels of nitrogen fertilizers were analyzed to explore the responses of tea plants to nitrogen stress. The primary maximum photochemical efficiency of PSII(F_v/F_m), the photochemical quenching coefficient (qP) and the relative electron transport rate (rETR) decreased under nitrogen deficiency (ND) and high nitrogen treatments (HN) in tea plant. Meanwhile, the levels of reactive oxygen species (ROS) increased significantly under ND/HN treatments, and the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) increased under HN/ND treatments. The relative expressions of antioxidant biosynthesis enzyme genes (CsSOD, CsPOD, CsCAT and CsAPX) were up-regulated under ND/HN treatments. Furthermore, the change trend of total free amino acid content under ND/HN treatments showed that nitrogen stress was not conducive to the accumulation of free amino acid content in tea, which may be related to the increase in ROS. This study presents a potential approach to improve tea quality by balancing ROS and antioxidant systems.

The substitution of chemical nitrogen (N) with organic fertilizers in tea plantations has been widely recognized as a strategy to maintain tea yield and improve soil quality, ensuring the sustainability of tea production systems. However, the effects of long-term organic-fertilizer substitution on tea yield and quality, soil properties, and bacterial communities have yet to be fully investigated, and the underlying mechanisms affecting tea yield and quality remain unclear. We conducted a six-year-long field experiment in a tea plantation to investigate the relationships among soil properties, bacterial communities, and the yield and quality of tea. Four treatments were compared: no fertilizer (NF), conventional fertilization (CF), 50% chemical N fertilizer substituted with a microbial organic fertilizer (MF), and 50% chemical N fertilizer substituted with a special organic fertilizer for tea (OF). The results showed that the substitution of organic fertilizers increased the spring tea yield by 6.4%~8.5% and the amino acid content of tea by up to 7.8%, while reducing tea polyphenol levels by 1.2–4.4% compared to CF. The soil quality improved significantly, with total phosphorus rising by 20.0% (MF) and 22.9% (OF), and soil organic matter increasing notably in the MF treatment group. The soil quality index (SQI) improved by 38.6% in the OF treatment group compared to the CF treatment group. Organic treatments reshaped bacterial communities, with the OF boosting Acidobacteriota (36.4%) and Planctomycetota (444.4%), and the MF enriching Actinobacteria and Gemmatimonadetes. Bacterial diversity (Shannon and Chao1 indices) correlated positively with the soil organic matter, total nitrogen, and pH. Changes in microbial communities were driven by pH, soil organic matter, and nitrogen levels. The partial least squares path model analysis confirmed that fertilization indirectly influenced tea yield (67% variance explained) and quality (79% variance explained) via soil properties and bacterial communities. These findings highlight the potential of organic-fertilizer substitution to promote sustainable tea production.

Tea is a popular daily beverage worldwide, especially in China. Tea white scab disease affects tea quality is poorly understood. In the current study, we aimed determine whether tea quality will variation. we collected green tea samples from five samples (with varying morbidity from CK to Ⅳ on Baiyun Mountain in Hunan Province. Results showed that tea quality are obviously decreased as infected by tea white scab disease . Results showed that an increase in incidence rate decreased total tea polyphenols (TP) , water extract and caffeine but increased amino acids (AA) , Nonetheless, the constituents of polyphenolic compounds were differentially altered. Additionally, the percentage of (−)-epicatechin (EC) and (−)-epicatechin-3-gallate (ECG) increased with increasing morbidity. (−)-epigallocatechin (EGC) and (−)-epigallocatechin-3-gallate(EGCG) just the opposite. The constituents of AA, especially Alanine, γ-aminobutyric acid, serine and phenylalanine increased with increasing elevational gradients. Proline, and theanine were reduce along with morbidity level. As a whole. This observation demands development of effective measures for sustaining green tea quality in the face of tea white scab disease.