Jasmonate- and abscisic acid-activated AaGSW1-AaTCP15/AaORA transcriptional cascade promotes artemisinin biosynthesis in Artemisia annua.

Artemisinin, a sesquiterpene lactone widely used in malaria treatment, was discovered in the medicinal plant Artemisia annua. The biosynthesis of artemisinin is efficiently regulated by jasmonate (JA) and abscisic acid (ABA) via regulatory factors. However, the mechanisms linking JA and ABA signalling with artemisinin biosynthesis through an associated regulatory network of downstream transcription factors (TFs) remain enigmatic. Here we report AaTCP15, a JA and ABA dual-responsive teosinte branched1/cycloidea/proliferating (TCP) TF, which is essential for JA and ABA-induced artemisinin biosynthesis by directly binding to and activating the promoters of DBR2 and ALDH1, two genes encoding enzymes for artemisinin biosynthesis. Furthermore, AaORA, another positive regulator of artemisinin biosynthesis responds to JA and ABA, interacts with and enhances the transactivation activity of AaTCP15 and simultaneously activates AaTCP15 transcripts. Hence, they form an AaORA-AaTCP15 module to synergistically activate DBR2, a crucial gene for artemisinin biosynthesis. More importantly, AaTCP15 expression is activated by the multiple reported JA and ABA-responsive TFs that promote artemisinin biosynthesis. Among them, AaGSW1 acts at the nexus of JA and ABA signalling to activate the artemisinin biosynthetic pathway and directly binds to and activates the AaTCP15 promoter apart from the AaORA promoter, which further facilitates formation of the AaGSW1-AaTCP15/AaORA regulatory module to integrate JA and ABA-mediated artemisinin biosynthesis. Our results establish a multilayer regulatory network of the AaGSW1-AaTCP15/AaORA module to regulate artemisinin biosynthesis through JA and ABA signalling, and provide an interesting avenue for future research exploring the special transcriptional regulation module of TCP genes associated with specialized metabolites in plants.

[Comparative study on substituting hedyseri radix for astragali radix in serum containing yiqiyangxue prescription on aged mice spleen lymphocyte proliferation and anti-oxidant effect].

OBJECTIVE: By substituting Hedyseri Radix for Astragali Radix in Yiqiyangxue prescription, to compare the effects of both serum containing medicine on aged mice spleen lymphocyte proliferation and anti-oxidant effect. METHOD: After using the same dose of Hedyseri Radix to replace Astragali Radix in Yiqiyangxue prescription, the best concentration of serum containing medicine,the best incubation time and the effects of ConA-induced spleen lymphocyte proliferation were determined by MTY method. Use reagent kits to detect the activity of SOD, MDA and ROS levels in aged mice spleen lymphocytes and IL-2 level in culture supernatant fluid of spleen lymphocytes. RESULTS: Both serum containing medicine can enhance the proliferation of aged mice spleen lymphocytes. The best concentration of serum containing medicine was 40% and the incubation time was 72 h. The serum containing Yiqiyangxue of Hedyseri Radix prescription acted more effective than that of Astragali Radix on the enhancement of proliferation. Both serum containing medicine showed similar effects on increasing SOD activity, IL-2 level and decreasing MDA and ROS level. Moreover,serum of Hedyseri Radix was superior in the enhancement of proliferation, IL-2 and the reduction of ROS level. CONCLUSION: Both serum containing medicine of Hedyseri Radix and Astragali Radix generate the same effect of anti-aging and enhancement of proliferation.

Induction and flow cytometry identification of tetraploids from seed-derived explants through colchicine treatments in Catharanthus roseus (L.) G. Don.

The tetraploid plants of Catharanthus roseus (L.) G. Don was obtained by colchicine induction from seeds explants, and the ploidy of the plants was identified by flow cytometry. The optimal treatment is 0.2% colchicine solution treated for 24 hours, and the induction rate reaches up to 30%. Comparing with morphological characteristics and growth habits between tetraploids and the control, we found that tetraploids of C. roseus had larger stoma and more branches and leaves. HPLC analysis showed tetraploidization could increase the contents of terpenoid indole alkaloids in C. roseus. Thus, tetraploidization could be used to produce higher alkaloids lines for commercial use. QRT-PCR results showed that the expression of enzymes involved in terpenoid indole alkaloids biosynthesis pathway had increased in the tetraploid plants. To our knowledge, this was the first paper to explore the secondary metabolism in autotetraploid C. roseus induced by colchicine.

Molecular cloning and expression profile analysis of Ginkgo biloba DXS gene encoding 1-deoxy-D-xylulose 5-phosphate synthase, the first committed enzyme of the 2-C-methyl-D-erythritol 4-phosphate pathway.

Plant diterpenes such as ginkgolides are biosynthesized via the recently discovered 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. The initial step of the MEP pathway is the formation of 1-deoxy-D-xylulose 5-phosphate (DXP) catalyzed by 1-deoxy-D-xylulose 5-phosphate synthase (DXS, EC: 4.1.3.37), which may thus be considered the first committed step of the MEP pathway for ginkgolides biosynthesis. The full-length cDNA of DXS was isolated and characterized from the gymnosperm plant species, Ginkgo biloba. The full-length cDNA of GbDXS was 2795 bp containing a 2154 bp open reading frame (ORF) encoding 717 amino acids. Comparative and bioinformatic analyses revealed that GbDXS has extensive homology with DXSs from other plant species and, like these, contains a conserved transit peptide for plastid import, histidine residue, a putative thiamine diphosphate-binding site and a transketolase motif. Phylogenetic analysis indicates that GbDXS belongs to the plant DXS1 cluster and suggests it to be more ancient than other plant DXSs. GbDXS was found to be expressed in all tested tissues including roots, stems, leaves, pericarps and seeds. Expression profiling analyses revealed that GbDXS expression was induced by exogenous elicitors including methyl jasmonate, arachidonic acid, acetylsalicylic acid and ceric ammonium sulfate, and showed that the transcription levels were correlated with ginkgolide accumulation, suggesting that DXS might play a regulatory role in ginkgolide biosynthesis in cell culture of G. biloba at the transcriptional level.