Monoterpenoids serve as essential components of plant essential oils and play significant roles in plant growth, development, and insect resistance. Artemisia annua, an important medicinal plant, produces abundant terpenoids. While previous research on A. annua has predominantly focused on artemisinin biosynthesis and its regulation, studies on other terpenoids in this plant have significantly lagged behind. To comprehensively investigate monoterpene biosynthesis in A. annua, we analyzed monoterpenes across its different tissues using optimized extraction and chromatographic conditions developed to enhance sensitivity and resolution in our GC-MS-based analytical method. In A. annua, 31 monoterpenoid compounds were identified. Subsequently, eight candidate monoterpene synthases (mTPS) were characterized in Escherichia coli, confirming their catalytic activity in converting geranyl pyrophosphate (GPP) into distinct monoterpene products. Subcellular localization revealed these TPSs in chloroplasts, consistent with the widely reported chloroplast localization of TPS enzymes. These enzymes were functionally defined as monoterpenoid synthases, collectively responsible for synthesizing 18 monoterpenoid metabolites. Notably, AaTPS13, AaTPS19, and AaTPS20 exhibited substantial product promiscuity. Critically, the AaTPS19 was identified as the first known terpene synthase producing 2-pinanol. These findings systematically elucidate the biosynthesis of monoterpenoids in A. annua and provide key enzymatic elements for metabolic engineering and synthetic biology applications in monoterpenoid production.

Gardenia jasminoides is a traditional edible fruit used in food coloring and herbal beverages. Despite its low total flavonoid content, the fruit exhibits specific enrichment of certain flavonoid metabolites, yet the underlying mechanisms remain unclear. This study aimed to characterize the tissue specific flavonoid profile, elucidate the putative biosynthetic pathway of fruit specific flavonoids, and predict their potential KEAP1 binding activity. Integrated metabolomics using LC-MS, qPCR, and molecular docking were performed across five tissues including stem, leaf, flower bud, flower, and fruit. A total of 116 flavonoids were identified across positive and negative ion modes, among which eight fruit-specific flavonoids were discovered. qPCR analysis revealed that branch pathway genes FNSII-1 and F3H were specifically upregulated in fruits compared with other tissues, suggesting that their fruit‑specific expression drives the accumulation of characteristic flavonoids in G. jasminoides fruits. Molecular docking with the KEAP1 Kelch domain showed that two fruit-specific aglycones, 4',5,7-trimethoxyflavonol and 5,2'-dihydroxy-7,4'-dimethoxyflavanone, exhibited binding energies of -6.87 and -6.72 kcal/mol, respectively, comparable to luteolin (-6.83 kcal/mol). These findings provide a molecular basis for understanding fruit-specific flavonoid accumulation in G. jasminoides and support its potential as a natural source of dietary antioxidant candidates for functional food applications.

GRAS transcription factors are essential for plant growth and stress adaptation, yet they remain uncharacterized in the medicinal herb Coptis chinensis. To address this gap, we performed a genome-wide identification of the GRAS family and investigated its transcriptional responses to temperature and light stress, integrating comparative transcriptomics with promoter analysis to explore potential co-expression with bZIP factors. A total of 48 CcGRAS genes were identified and found to be unevenly distributed across nine chromosomes. Expression profiling revealed that CcGRAS genes are markedly more responsive to varying light intensities (476, 8340 lx) than to temperature stresses (15, 35 °C), relative to controls (2060 lx for light, 25 °C for temperature). Co-expression analysis uncovered an underground tissue-specific module in which CcbZIP16 is upregulated with four CcGRAS genes (CcGRAS11, CcGRAS12, CcGRAS43, CcGRAS48) that are coordinately upregulated specifically under low-light conditions. The promoters of these co-expressed genes are significantly enriched in canonical light-responsive cis-elements, providing correlative evidence for their coordinated transcriptional control. Together, these findings identify a tissue-specific GRAS-bZIP co-expressed gene set under light stress and suggest a candidate regulatory framework for dissecting light adaptation mechanisms. This work also provides a foundation for targeted genetic improvements in stress tolerance and alkaloid biosynthesis in this important medicinal plant.

The medicinal and edible plant Gardenia jasminoides is attracting attention as a source of natural food-active components. Integrated GC–MS/LC-MS metabolomics revealed that G. jasminoides fruits specifically accumulate bioactive triterpenoids, including the GRAS antioxidant squalene (220 ng/mg FW) and methyl oleanonate, a compound with reported anticancer (PPARγ agonist) activity. As the central biosynthetic hub, GjSQS showed fruit-predominant expression, strongly correlating with triterpenoid abundance. Functional validation confirmed its ER localization and efficient in vitro conversion of FPP to squalene. The dual-ionization LC-MS approach revealed tissue-partitioned acidic triterpenoids that were undetectable using single ionization modes, enhancing the comprehensiveness of metabolomic profiling. These findings underscore G. jasminoides fruits as a sustainable source of food-active triterpenoids and establish GjSQS as a key metabolic engineering target. Its expression in food-grade microbial chassis offers a promising strategy to enhance the production of high-value triterpenoids for functional foods and additives.