| Artemisia annua L.,a tranditional Chinese medicinal herb,is the only plant source of artemisinin widely used as a first-line antimalarial drug.At present,A.annua plants has limited natural resources and low artemisinin content,which cannot meet the requirements of large-scale production and application.Therefore,the study of artemisinin biosynthesis has attracted inclusive attention.Polyploidy is an important marker for the evolution of higher plants.Polyploidy has a positive influence on the growth and development of plants as well as the accumulation of active metabolites.In this study,polyploidization has become an effective strategy for increasing the artemisinin content of plants.The study is as follows:1.In our experiment,tetraploid was induced by colchicine.The leaves of A.annua were treated with 0.1% colchicine solution and soaked in the dark for 24 h to obtain regenerated anthers plants.The ploidy level of A.annua was confirmed by flow cytometry and chromosome counts.2.The changes of physiology and biochemistry were studied between diploids and tetraploids.In tetraploids(No.AA-T2),artemisinin content in leaves increased by 42% than that of diploid(No.AA-D5)at growth stage.Leaf area,plant size,and root length were all observed significant changes.The size of glandular trichome and stomata in the leaves was increased.No significant difference in trichome density,but stomatal density decreased.Photosynthetic pigments and photosynthesis also changed obviously.3.A series of physiological experiments were conducted to investigate the responses of A.annua to polyploidy.Firstly,polyploidization caused a series of epigenetic changes in A.annua,we verified the genomic DNA methylation,and subsequently demonstrated that 5-methylcytosine content in tetraploid was 2.9-fold than that of diploid.At the same time,the content of reactive oxygen species(ROS)was measured,the content of superoxide anion in tetraploid increased significantly.The endogenous phytohormone jasmonic acid(JA),abscisic acid(ABA)and indole-3-acetic acid(IAA)contents in leaves were determined by ELISA.The level of JA was consistently higher in tetraploids.ABA and IAA content also show significant dynamic changes at different stages of growth.4.We performed a comprehensive transcriptome characterization of A.annua diploids and induced autotetraploids to investigate the molecular mechanisms underlying the physiological effects of polyploidization and the regulation of plant growth and artemisinin biosynthesis.A total of 8,763 differentially expressed unigenes(DEGs)between diploid and tetraploid libraries was identified through transcriptomic analysis.Based on a comparison of DEGs,we found that polyploidy resulted in altered expression of genes involved in phenotypic,physiological,and artemisinin biosynthesis.These DEGs are mainly involved in carbohydrate metabolism,cell wall organization and defense responses.In addition,the up-regulated genes were mainly enriched in response to extracellular protein biosynthesis,photosynthesis,and phytohormone-stimulated cell enlargement and phenotypic changes.The induction of oxidative stress-related gene expression changes,ABA and JA biosynthesis and signal transduction,and artemisinin biosynthetic pathway key enzymes and some transcription factor activation,leading to increased artemisinin accumulation.Our paper is the first transcriptomic study to analyze the perspective of polyploidization in A.annua.The results provided understanding of the complexity of polyploidization and new information of the further identification of transcription factors and genes involved in artemisinin biosynthesis.These data provide new insights into the genetic and physiological regulation of polyploidization in A.annua.Salvia miltiorrhiza Bunge,whose dried roots and rhizomes are widely used for the treatment of cardiovascular and cerebrovascular diseases in clinical.In this paper,the synthesis of cyclodextrin-silver-nanoparticles effectively increased the content of tanshinone compounds in S.miltiorrhiza hairy roots and the molecular mechanism of this induction were probed,which provided the basis for further research and development of S.miltiorrhiza.1.Nanoparticles refer to atoms or aggregates having at least one dimension at 1-100 nm.The unique performance of the nanoparticles has given it great attention.We successfully synthesized spherical β-CD-Ag nanoparticles(Ag NPs)with an average particle size of 51 nm using cyclodextrin(β-CD)and silver nitrate.It was found that Ag NPs can increase the yield of tanshinones effectively,when the optimal treatment conditions was 30 mg/L for 7 day culture.At this time,the yield of tanshinone reached to 10.76 mg/L,which was 1.8-fold than that of the control.2.Through a series of experiments to explore the effect of Ag NPs on tanshinone biosynthesis,we found that the induction of Ag NPs mainly comes from the impact of nanoparticles themselves.When the free Ag+ ions were chelated in solutions,the yields of tanshinone in hairy roots were still higher than that of control group.Nanoparticles promoted the burst of reactive oxygen species,and affect the expression of key enzyme genes(including Sm HMGR,Sm DXR,Sm DXS,Sm GGPPS,Sm CPS,and Sm KSL)in the tanshinone biosynthesis pathway.The relationship between nanoparticles and secondary metabolism provides a basis for the use of Ag NPs to improve the production of tanshinones. |
PDF Full Text Request