Liangjie Niu, Chunhui Wang, Jiayin Xie, Lin Cheng, Qiying Zhou, Wei Wang
Storage duration significantly influenced the Yuba metabolome, as evidenced by clear separation in Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) scores. Glycerophospholipid and fatty acyl metabolism were significantly altered, with increases in LysoPEs, LysoPA, PCs, and fatty acyls observed during prolonged storage. At the microbial level, Firmicutes dominated throughout storage, with a shift towards increasing abundance of Firmicutes and decreasing abundance of Proteobacteria as storage time increased. Lysinibacillus emerged as the predominant genus after long-term storage (460 days), showing a significant increase in relative abundance from 0.27% to 52.33%. Specific bacterial genera, notably Lysinibacillus and Macrococcus, demonstrated significant correlations with metabolite levels, suggesting their crucial roles in shaping the Yuba metabolome. Microbial functional predictions were associated with lipid, amino acid, and nucleotide metabolism. Eleven common pathways were identified between significantly altered microbes and metabolites, including glycerophospholipid metabolism and amino acid biosynthesis.
Green tea quality is largely determined by the metabolite profile of fresh leaves. However, the time-of-day-dependent dynamics of these metabolites remain largely unknown in Xinyang Maojian (XYMJ), a premium Chinese green tea. In this study, we performed the first integrative transcriptomic and metabolomic analysis of Camellia sinensis cv. Xinyang 10 shoots (one bud and one leaf) sampled at 7:00, 13:00, and 18:00 under field conditions with light intensities of 19.2, 113, and 5.4 klx, respectively. We identified 525 differentially accumulated metabolites and 19,767 differentially expressed genes exhibiting distinct time-of-day-dependent patterns. Physiological measurements confirmed significant fluctuations in starch, soluble sugars, chlorophyll, relative water content, and polyphenols throughout the daytime. A key finding was a daytime carbon allocation trade-off: primary metabolism (starch biosynthesis, glycolysis, TCA cycle) peaked at 13:00, whereas secondary metabolism (flavonoids, theaflavins, phenolic acids, anthocyanins) dominated at 18:00, supported by strong negative correlations between primary and secondary metabolic modules. Chlorophyll and oligomeric catechins peaked at 7:00; theaflavins at 13:00; and starch, soluble sugars, theanine, and organic acids at 18:00. Light-responsive transcription factors (bZIP, NF-Y, HD-Zip, SPL, ARF, MADS) and other regulators (MYB, AP2/ERF, WRKY, NAC, GRAS, bHLH) exhibited time-specific expression, sequentially modulating flavonoid, caffeine, and theanine biosynthesis, along with specific gene modules including SS3/SS4 (starch synthesis), BAM3 (starch degradation), FBA1 (carbon fixation), CYP72A219 (terpenoid metabolism), and L7A (theaflavin biosynthesis). Evening-harvested leaves accumulated higher levels of theanine (umami) and soluble sugars (sweetness), whereas morning leaves were enriched in astringent catechins and flavonols. This multi-omics dissection of time-of-day-dependent metabolism in XYMJ tea provides a scientific basis for time-of-day harvesting strategies and graded processing of tea products.