Fangyuan Zhang

Based on field surveys, examination of herbarium specimens, and molecular phylogenetic analyses, the present study described a new species, Hydrangea medogensis sp. nov . (Hydrangeaceae), from Medog County, Xizang Autonomous Region, China. Phylogenetic analyses indicated that H. medogensis was placed in Clade 1 as a distinct lineage, sister to the remainder of the clade. Morphologically, the new species is most similar to H. stylosa but can be distinguished by the following key characteristics: fertile flowers with a globose calyx tube constricted at the mouth; calyx teeth triangular, occasionally oblong-ovate, 0.6–1 mm long; adaxial leaf surface covered with two types of soft hairs (long and short); ovary more than 4/5 inferior, nearly completely inferior; and seeds with a very narrow wing around the margin. The taxonomic status of the new species was established based on integrated morphological and molecular evidence.

Artemisinin, a sesquiterpene lactone produced in Artemisia annua, is the most effective antimalarial compound, but its low natural abundance in A. annua remains a major bottleneck for large-scale production. Increasing its biosynthesis requires a better understanding of the regulatory networks controlling artemisinin biosynthesis genes. Several jasmonate (JA)-responsive transcription factors have been characterized, but the role of upstream kinases remains poorly understood. Here, we identify AaSnRK2.6, a SnRK2III-type protein kinase, as a novel positive regulator of artemisinin biosynthesis. AaSnRK2.6 expression was strongly induced by methyl jasmonate and abscisic acid, and the protein is localized to both the cytoplasm and nucleus. Protein interaction assays revealed that AaSnRK2.6 specifically interacts with the JA-responsive TF AaORA in the nucleus, and an in vitro kinase assay further showed that AaSnRK2.6 directly phosphorylates AaORA. Dual-luciferase assays showed that AaSnRK2.6 enhances AaORA-mediated activation of key artemisinin biosynthetic genes (amorpha-4,11-diene synthase, DBR2, and ALDH1). Overexpression of AaSnRK2.6 alone or AaORA alone significantly increased artemisinin and dihydroartemisinic acid accumulation, while co-overexpression of AaSnRK2.6 and AaORA in transgenic plants produced the stronger effect. By contrast, RNA interference knockdown of AaSnRK2.6 showed no significant effect on artemisinin levels, likely due to functional redundancy of kinases. Collectively, this study supports a positive kinase-TF regulatory module involved in hormone-responsive artemisinin biosynthesis in A. annua and provides new insights into its regulatory mechanism.

Mirabilis himalaica (Edgew.) Heimerl (Nyctaginaceae) is a Tibetan medicinal plant of the Caryophyllales that accumulates red-violet betacyanins, yet its betacyanin biosynthetic genes and the 3,4-dihydroxyphenylalanine (DOPA) 4,5-dioxygenase (DODA) paralog responsible for betalamic acid formation betalamic acid formation have not been characterised. From a six-tissue de novo transcriptome, we identified and cloned six candidate genes (MhADH, MhCYP76AD1, MhDODA1, MhDODA2, MhSDODA, and MhcDOPA5GT) and analysed their phylogeny and tissue expression. MhSDODA denotes the candidate that groups with the functionally characterised Mirabilis jalapa MjDODA1. We reconstituted the pathway by transient co-expression in Nicotiana benthamiana and overexpressed MhSDODA in M. himalaica. Under the transient-expression conditions tested, MhCYP76AD1 + MhSDODA was the smallest combination of introduced genes producing visible pigmentation (188 µg betanin equivalents·g⁻¹ fresh weight determined by high-performance liquid chromatography). Betacyanin content rose to 351 µg·g⁻¹ when MhcDOPA5GT was added and to 544 µg·g⁻¹ when MhADH was added as well. Among the three DODA paralogs, only MhSDODA co-expressed with MhCYP76AD1 produced strong pigmentation, whereas MhDODA1 and MhDODA2 yielded little to no pigment under the same conditions. Native overexpression of MhSDODA increased betacyanin content approximately threefold across three independent lines. These results provide the first functional characterisation of betacyanin biosynthetic genes in M. himalaica and identify MhSDODA as the major functional DODA paralog among those tested.

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.

Terrestrialization is an important evolutionary process that plants experienced. However, little is known about how land plants acquired aquatic growth behaviors. Here, we integrate multiproxy evidence to elucidate the evolution of the aquatic plant duckweed. Three genera of duckweeds show chronologically gradual degeneration in root structure and stomatal function and a decrease in lignocellulose content, accompanied by the contraction of relevant gene families and/or a decline in their transcription levels. The number of genes in main phytohormone pathways is also gradually decreased. The coordinated action of genes involved in auxin signaling and rhizoid development causes a gradual decrease in adventitious roots. Additionally, the significant expansion of the flavonoid pathway is related to the adaptation of duckweeds to floating growth. This study reconstructs the evolutionary history of duckweeds, tracing its journey from land back to water — a reverse trajectory of early land plants.

Artemisinin, a crucial antimalarial compound synthesized in Artemisia annua, is tightly controlled by various transcription factors. Despite significant progress in understanding this regulatory network, further exploration of additional factors is needed to improve artemisinin biosynthesis. Here, we identified a novel R2-MYB-like transcription factor, AaMYB121, which responds to methyl jasmonate (MeJA). Overexpression of AaMYB121 in transgenic A. annua plants resulted in dihydroartemisinic acid (DHAA) content being elevated 2~3 times compared to the control, while artemisinin levels increased to 1.4~2 times, significantly boosting artemisinin biosynthesis. Dual-Luciferase (Dual-LUC) assay and yeast one-hybrid (Y1H) analysis demonstrated that AaMYB121 directly binds to the promoter motifs of DBR2 (−1146~−1103) and ALDH1 (−1558~−1504), thereby triggering the transcriptional initiation of these genes. Notably, AaMYB121 features an elongated DNA-binding domain that specifically recognizes AT-rich cis-elements in the promoters of key artemisinin biosynthetic genes. These findings established AaMYB121 as a novel MYB-like transcription factor with strong potential to enhance the regulation of artemisinin production through targeted modulation, offering a valuable approach to improve artemisinin yields for therapeutic purposes.

Mirabilis himalaica, known for its medicinal properties and limited distribution in the Qinghai-Xizang Plateau, is under conservation pressure due to high market demand. Traditional transformation methods are inefficient for this species, prompting the development of a non-tissue culture approach. This study utilized mature leaves as explants and employed a cut-dip-budding (CDB) system to transform fluorescence and betacyanin reporter systems in M. himalaica, successfully transforming a high-altitude Xizang medicinal plant. The study found that mature leaves exhibited robust regeneration potential, making them ideal for large-scale transformation. The transformation system achieved approximately 76% positive rooting rate and a 2% positive transgenic plant rate. This method overcomes challenges associated with Agrobacterium tumefaciens-mediated transformation and lays the foundation for future genetic research and industrial applications of Xizang medicinal plants.

Leontopodium nyingchiense, a new species of Asteraceae from the Xizang (Tibet) Autonomous Region of China, is described and illustrated here. Morphologically, it is most similar to L. lingianum but can be distinguished by the combination of monoecious and dioecious individuals, involucral bracts arranged in 3–5 series (with outer series herbaceous and middle to inner series membranous), fimbriate apices on female florets, rough-edged lobes on male florets, and achenes lacking costae. Phylogenetic analyses further support the separation of this new species from related taxa. Finally, we characterize this new species through both morphological comparisons and molecular analyses.

Anisodus luridus, a perennial herb belonging to the genus Anisodus of the Solanaceae family, is an important Tibetan medicinal plant that produces pharmaceutical tropane alkaloids (TAs) including hyoscyamine and scopolamine. Its high yield of hyoscyamine makes A. luridus a valuable plant source for commercially producing TAs. In this study, we conduct homologous gene research across transcriptome data of different tissues together with functionally tested sequences in Atropa belladonna as a reference and identify 13 candidate genes for TAs biosynthesis in A. luridus. The results show that these 13 TAs biosynthesis genes identified in A. luridus were highly conserved in terms of sequence similarity and gene expression patterns compared to A. belladonna, suggesting that the two species may share the same biosynthetic pathway for TAs biosynthesis. Furthermore, scopolamine was detected in Nicotiana benthamiana leaves when these 13 enzymes were co-expressed in N. benthamiana, which confirmed that these 13 TAs biosynthesis genes are involved in the biosynthesis of TAs. The results of our study not only systematically elucidate the tropane alkaloid biosynthetic pathway of A. luridus, but also realize the de novo synthesis of TAs in N. benthamiana for the first time. It is now possible to make N. benthamiana a potential source for TAs production through synthetic biology techniques.