Fertilization is an essential aspect of tea plantation management that supports a sustainable tea production and drastically influences soil microbial communities. However, few research studies have focused on the differences of microbial communities and the variation in tea quality in response to different fertilization treatments. In this work, the soil fertility, tea quality, and soil microbial communities were investigated in two domestic tea plantations following the application of chemical and organic fertilizers. We determined the content of mineral elements in the soil, including nitrogen, phosphorus, and potassium, and found that the supplementation of chemical fertilizer directly increased the content of mineral elements. However, the application of organic fertilizer significantly improved the accumulation of tea polyphenols and reduced the content of caffeine. Furthermore, amplicon sequencing results showed that the different ways of applying fertilizer have limited effect on the alpha diversity of the microbial community in the soil while the beta diversity was remarkably influenced. This work also suggests that the bacterial community structure and abundance were also relatively constant while the fungal community structure and abundance were dramatically influenced; for example, Chaetomiaceae at the family level, Hypocreaceae at the order level, Trichoderma at the genus level, and Fusarium oxysporum at the species level were predominantly enriched in the tea plantation applying organic fertilizer. Moreover, the bacterial and fungal biomarkers were also analyzed and it was found that Proteobacteria and Gammaproteobacteria (bacteria) and Tremellomycetes (fungi) were potentially characterized as biomarkers in the plantation under organic fertilization. These results provide a valuable basis for the application of organic fertilizer to improve the soil of tea plantations in the future.

Hunan located at the evolutionary transitional zone edge of the Yunnan-Guizhou plateau, tea germplasms are abundant. At present, although morphological, enzymological and molecular markers have been used to study the genetic relationship of these tea germplasms. However, due to the complexity of the genetic background of tea germplasm resources, the evolution history and taxonomy of Hunan tea germplasm is still unclear. In this study, four Hunan tea landraces from the evolutionary transitional zone were collected, including 9 'Chengbu Dongcha' (CBDC), 8 'Jianghua Kucha' (JHKC), 11 'Rucheng Baimao' (RCBM) and 8 'Anhua Yuntai' (AHYT). We used whole-genome re-sequencing to identify genetic variation, phylogenetic placement, and population structure among the four tea landraces and then scanned the genome for regions related to population potential selective. Across the samples, we identified an average of 1.38 million (M) SNPs and 6.82 × 10³ INDELs. Based on the high-quality SNPs, we performed neighbor-joining phylogenetic tree, population structure, and principal component analysis, all of which supported that the 36 tea germplasms could been divided into two groups, CBDC and AHYT were clustered into a group, and RCBM and JHKC were clustered into another group. With CBDC, JHKC, and RCBM as control, 407, 380, and 147 selected genes were identified in AHYT, respectively, were in the top 5% of F_ST and Log₂^Ratioθπ scores. The identified genes are mainly involved in stress tolerance, biosynthesis of important secondary metabolites, adaptability, and yield. These results will be helpful in the classification of tea germplasms and investigating selection–related genes.

Background: Heterosis (hybrid vigor) is a fundamental phenomenon in plant breeding, but its molecular basis remains poorly understood in perennial crops such as tea (Camellia sinensis). This study aimed to elucidate the molecular mechanisms underlying heterosis in tea and its hybrids by performing integrated transcriptomic and metabolomic analyses of F₁ hybrids derived from two elite cultivars, Fuding Dabaicha (FD) and Baojing Huangjincha 1 (HJC). Methods: Comprehensive RNA sequencing and widely targeted metabolomic profiling were conducted on the parental lines and F₁ hybrids at the one-bud-one-leaf stage. Primary metabolites (including amino acids, nucleotides, saccharides, and fatty acids) were quantified, and gene expression profiles were obtained. Transcriptomic and metabolomic datasets were integrated using KEGG pathway enrichment and co-expression network analysis to identify coordinated molecular changes underlying heterosis. Results: Metabolomic profiling detected 977 primary metabolites, many of which displayed non-additive accumulation patterns. Notably, linoleic acid derivatives (9(S)-HODE, 13(S)-HODE) and nucleotides (guanosine, uridine) exhibited significant positive mid-parent heterosis. Transcriptomic analysis revealed extensive non-additive gene expression in F₁ hybrids, and upregulated genes were enriched in fatty acid metabolism, nucleotide biosynthesis, and stress signaling pathways. Integrated analysis demonstrated strong coordination between differential gene expression and metabolite accumulation, especially in linoleic acid metabolism, cutin/suberine biosynthesis, and pyrimidine metabolism. Positive correlations between elevated fatty acid levels and transcript abundance of lipid metabolism genes suggest that the transcriptional remodeling of lipid pathways contributes to heterosis. Conclusions: These findings provide novel insights into tea plant heterosis and identify potential molecular targets for breeding high-quality cultivars.