Intercropping with green manure is a soil-sustainable cultivation practice that has demonstrated positive impacts on tea growth and the soil environment in tea plantations. Nevertheless, research examining the effect of leguminous green manure varieties in tea plantations is scarce. This study aimed to analyze the tea quality and soil environment components in response to intercropping with three distinct leguminous green manures, Cassia sophera cv. Chafei 1 (CF), Sesbania cannabina (Retz.) Pers. (SC), and Chamaecrista rotundifolia (Pers.) Greene (CR), with 70% chemical fertilizer, and compare them to non-intercropped green manures with 100% chemical fertilizer (CK) in tea plantations. The findings indicated that intercropping with SC increased the amino acids content of tea leaves, the soil organic carbon (SOC), the soil acid phosphatase (ACP), the soil acid protease (ACPT), and the bacterial diversity compared to the CK treatment. Intercropping with CR improved the ACP activity and bacterial diversity while intercropping with CF improved the polyphenols. Proteobacteria, Acidobacteria, Actinomycetes, and Firmicutes were identified as the dominant bacterial taxa in tea plantations with intercropped green manure. A strong positive correlation was indicated between the SOC contents and the amino acids content in tea leaves after intercropping. A canonical correspondence analysis indicated significant associations between the ACP and the urease activity, and between the ACP and ACPT, and both were closely linked to SC. This finding provides an explanation that intercropping with SC may positively affect tea quality by influencing the SOC content, the soil enzyme activity, and the soil bacterial diversity. Green manure intercropping may replace part of chemical fertilizers, improve the soil environment in tea gardens, and enhance the quality of tea. These findings offer a theoretical reference for selecting leguminous green manure and advancing the sustainable development of tea plantations.

Intercropping legumes is an effective and sustainable planting pattern that has the benefit of decreasing chemical fertilizer input and improving the soil environment. However, the effects of chemical fertilizer reduction and intercropping different legumes on soil nutrients, microorganisms, and tea quality remain elusive. Hereby, compared with 100% chemical fertilizer (CK), Sesbania cannabina (SC) and Crotalaria pallida Blanco (CP) were selected as the intercropped plant with 70% chemical fertilizer to investigate its effect on soil nutrients, microorganisms, and tea quality. The results showed that compared with monocropping, intercropping legumes had greater concentrations of the soil labile organic matter, nitrate nitrogen, ammonia nitrogen, inorganic nitrogen, and alkali-hydrolyzable nitrogen. Intercropping systems significantly enhanced the content of non-ester-type catechins (catechin and gallocatechin) and ester-type catechins (epicatechin gallate). In SC, the content of gallocatechin, catechin, and epicatechin gallate increased by 146.67%, 107.69%, and 21.05%, respectively, while in CP, the content of these three compounds increased by 166.67%, 84.62%, and 19.08%, respectively. Significant differences in microbial composition were also observed under different systems. Actinobacteria, Rhodoplanes, and Thaumarchaeota were obviously enhanced in SC, while Rhodanobacter, Pseudolabrys, and Pedosphaera were manifestly improved in CP compared to those in the monoculture. Moreover, intercropping legumes significantly increased the abundances of CNP cycling functional genes, such as gpmB, mch, accD6, pgi-pmi, mcr, glmS, ACOX1 and fadB (carbohydrate metabolism), nirD and narI (nitrification), pmoB-amoB and hao (dissimilatory N reduction), and phoN (organic phosphoester hydrolysis). The relationship between intercropping systems and tea qualities was mainly established by soil nutrition and the abundance of C and N cycling functional microorganisms. This study provides more information on the relationship between soil nutrients, functional genes of microorganisms, and tea quality under tea/legume intercropping systems in tea plantations and offers a basis for the higher-performance intercropping pattern.

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.