salvianolic-acid-B and jasmonic-acid

Jasmonic acid (JA), as an important plant hormone, can induce the synthesis of phenolic acids in Salvia miltiorrhiza Bunge, a model medicinal plant, but the specific mechanism remains to be further elucidated. JA-responsive SmMYB111 positively regulates the biosynthesis of salvianolic acid B (SalB), but the molecular mechanism is unclear. Here, we found that SmMYB111 directly binds to the promoters of SmTAT1 and SmCYP98A14 and activates their transcription. Yeast two hybrid and bimolecular fluorescent complementation assay indicated that SmMYB111 interacts with SmJAZ4. Furthermore, we systematically characterized the function of SmJAZ4, which was highly expressed in flowers and roots and located in the nucleus and cell membrane. The contents of phenolic acids in the SmJAZ4-overexpressed transgenic plantlets and SmJAZ4-overexpressed transgenic hairy roots decreased significantly. SmJAZ4 interacts with SmMYC2 or SmMYB111 to repress their transcriptional activation activity on target enzyme genes of the biosynthesis pathway of phenolic acids. Overall, the molecular mechanism of SmJAZ4-SmMYC2/SmMYB111 module participating in JA signaling regulation of SalB biosynthesis was elucidated, which give a clue for the molecular regulation of phenolic acids biosynthesis in S. miltiorrhiza.

Topics: Gene Expression Regulation, Plant; Hydroxybenzoates; Plant Proteins; Plant Roots; Salvia miltiorrhiza

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Topics: Benzofurans; Cyclopentanes; Gene Expression Regulation, Plant; Indoleacetic Acids; Oxylipins; Plant Roots; Salvia miltiorrhiza; Transcription Factors

Basic helix-loop-helix (bHLH) transcription factors play essential roles in myriad regulatory processes, including secondary metabolism. In this study with Salvia miltiorrhiza, we isolated and characterized SmbHLH53, which encodes a bHLH family member. Expression of this gene was significantly induced by wounding and multiple hormones, including methyl jasmonic acid; transcript levels were highest in the leaves and roots. Phylogenetic analysis indicated that SmbHLH53 clusters withAtbHLH17 and AtbHLH13, two negative regulators of jasmonate (JA) responses, and is localized in the nucleus and cell membrane. Yeast two-hybrid and bimolecular fluorescent complementation assays indicated that SmbHLH53 forms a homodimer as well as a heterodimer with SmbHLH37. It also interacts with both SmJAZs1/3/8 and SmMYC2, the core members of the JA signal pathway. Unexpectedly, we noted that overexpression of SmbHLH53 did not significantly influence the concentrations of rosmarinic acid and salvianolic acid B in transgenic plants. Results from yeast one-hybrid assays showed that SmbHLH53 binds to the promoters of SmTAT1, SmPAL1, and Sm4CL9, the key genes for enzymes in the pathway for phenolic acid synthesis. Assays of transient transcriptional activity demonstrated that SmbHLH53 represses the promoter of SmTAT1 while activating the promoter of Sm4CL9. Thus, the present work revealed that SmbHLH53 may play dual roles in regulating the genes for enzymes in the pathway for Sal B biosynthesis.

Topics: Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Benzofurans; Biosynthetic Pathways; Cell Nucleus; Cyclopentanes; Oxylipins; Phylogeny; Plant Proteins; Promoter Regions, Genetic; Protein Interaction Maps; Protein Multimerization; Salvia miltiorrhiza; Secondary Metabolism; Signal Transduction

This study provides a desirable candidate gene resource (SmAOC) to increase the content of valuable natural products via appropriate JA pathway genetic engineering. Jasmonates (JAs) are important signal molecules in plants. They regulate transcripts of defense and secondary biosynthetic metabolite genes in response to environmental stresses. Currently, JAs are widely used as elicitors to improve the content of useful secondary metabolism in plants. Synthesis of the naturally occurring enantiomer of various jasmonates is catalyzed by allene oxide cyclase (AOC, EC 5.3.99.6). Here, we cloned and characterized the AOC gene (SmAOC) from Salvia miltiorrhiza. As expected, SmAOC expression was induced by abiotic stimuli such as methyl jasmonate (MeJA), ultraviolet radiation (UV) and low temperature (4 °C) in S. miltiorrhiza plantlets. To demonstrate whether the engineered internal JAs pool by overexpressing AOC gene could promote secondary metabolism production, the SmAOC was incorporated into S. miltiorrhiza hairy roots. The results revealed that SmAOC overexpression significant enhanced the yields of tanshinone IIA, rosmarinic acid (RA) and lithospermic acid B (LAB) in S. miltiorrhiza hairy roots. In addition, expression levels for key genes involved in the biosynthetic pathway of diterpenes and phenolic acids were also altered. These suggest that genetic manipulation of AOC would be helpful for improving the production of valuable secondary metabolites by regulating the biosynthesis of JAs.

Topics: Abietanes; Acetates; Benzofurans; Cinnamates; Cloning, Molecular; Cold Temperature; Cyclopentanes; Depsides; Diterpenes; Escherichia coli; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant; Genetic Engineering; Genetic Vectors; Hydroxybenzoates; Intramolecular Oxidoreductases; Oxylipins; Plant Roots; Rosmarinic Acid; Salvia miltiorrhiza; Transgenes; Ultraviolet Rays