{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T05:18:37Z","timestamp":1787635117441,"version":"build-2736575974"},"reference-count":47,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,22]],"date-time":"2026-08-22T00:00:00Z","timestamp":1787356800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Key Research Projects of Higher Education Institutions of Henan Provincial Department of Education, China","award":["26A210024"],"award-info":[{"award-number":["26A210024"]}]},{"name":"Scientific and Technological Research Projects of Henan Province, China","award":["262102110108"],"award-info":[{"award-number":["262102110108"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>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.<\/jats:p>","DOI":"10.3390\/plants15172558","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T09:20:02Z","timestamp":1787563202000},"page":"2558","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Integrative Transcriptomic and Metabolomic Analyses of Time-of-Day Variation of Quality-Related Metabolites in Fresh Tea Leaves"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7460-5489","authenticated-orcid":false,"given":"Liangjie","family":"Niu","sequence":"first","affiliation":[{"name":"Dabie Mountain Laboratory, Henan Key Laboratory of Tea Plant Biology, Henan International Joint Laboratory of Tea-Oil Tree Biology and High-Value Utilization, College of Tea and Food Science, Xinyang Normal University, Xinyang 464000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunhui","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Life Sciences, Henan Agricultural University, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiayin","family":"Xie","sequence":"additional","affiliation":[{"name":"Dabie Mountain Laboratory, Henan Key Laboratory of Tea Plant Biology, Henan International Joint Laboratory of Tea-Oil Tree Biology and High-Value Utilization, College of Tea and Food Science, Xinyang Normal University, Xinyang 464000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lin","family":"Cheng","sequence":"additional","affiliation":[{"name":"Dabie Mountain Laboratory, Henan Key Laboratory of Tea Plant Biology, Henan International Joint Laboratory of Tea-Oil Tree Biology and High-Value Utilization, College of Tea and Food Science, Xinyang Normal University, Xinyang 464000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiying","family":"Zhou","sequence":"additional","affiliation":[{"name":"Dabie Mountain Laboratory, Henan Key Laboratory of Tea Plant Biology, Henan International Joint Laboratory of Tea-Oil Tree Biology and High-Value Utilization, College of Tea and Food Science, Xinyang Normal University, Xinyang 464000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3711-5181","authenticated-orcid":false,"given":"Wei","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Life Sciences, Henan Agricultural University, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,22]]},"reference":[{"key":"ref_1","unstructured":"Food and Agriculture Organization of the United Nations (2021). 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