ABSTRACT
The present study analyzed the effects of planting density on the development, quality, and gene transcription characte-ristics of Rehmannia glutinosa using 85-5 and J9 as materials with three planting densities of 5 000, 25 000, and 50 000 plants/Mu(1 Mu≈667 m~2). The agronomic characteristics of leaves and tuberous roots, the content of catalpol and acteoside, and the changes of gene expression were determined. The results showed that the leaf size, the diameter of tuberous root, leaf biomass, tuberous root number, and tuberous root biomass per plant at low density were significantly higher than those of medium and high densities. The content of catalpol and acteoside in leaves was higher at high density. The content of catalpol in tuberous roots was higher at low density, and the change trend was similar to that in leaves, while the content of acteoside in tuberous roots was higher at high density. Transcriptome analysis found that about 1/2 of the expansin genes could change regularly in response to density treatment, which was rela-ted to the development of tuberous roots. The change trend of the gene expression of multiple catalytic enzymes involved in the biosynthesis of catalpol and acteoside was consistent with that of their content, which was presumedly involved in the accumulation and regulation of density-responsive medicinal components. Based on the analysis of the development, medicinal components, and gene expression characteristics of R. glutinosa at different densities, this study is expected to provide an important basis for regulating the quality and yield of medicinal materials of R. glutinosa by managing the planting density.
Subject(s)
Gene Expression Profiling , Plant Leaves/genetics , Plant Roots/genetics , Rehmannia/genetics , Transcription, GeneticABSTRACT
Objective:To explore the composition characteristics of rhizosphere soil under <italic>Rehmannia glutinosa-Zea mays</italic> intercropping model，and screen out special signal substances in rhizosphere soil of <italic>R. glutinosa</italic> under intercropping <italic>Z. mays</italic>， so as to provide the basis for the study of allelopathic substances in continuous cropping obstacle of <italic>R. glutinosa</italic>. Method:In this experiment，rhizosphere soils of <italic>R. glutinosa</italic> under <italic>Z. mays </italic>intercropping and <italic>R. glutinosa </italic>single cropping models in July，August，September and October were taken as the research objects， and the volatile organic compounds in ethyl acetate fraction were analyzed by gas chromatography-mass spectrometry （GC-MS）. Principal component analysis （PCA）， hierachical cluster analysis （HCA） and orthogonal partial least squares discriminant analysis （OPLS-DA） analysis were performed on the data by SIMCA 14.1 to screen out potential differences in volatile organic compounds between the two models. Result:The types of volatile organic compounds in intercropping and single cropping models were mainly hydrocarbons， alcohols， esters， ketones， amides， acids and other substances. Specifically， the average relative contents of hydrocarbons，esters and amides in intercropping model were 58.46%，32.15% and 5.42% respectively，while the relative contents of hydrocarbons，esters and amides in single cropping model were 37.27%，36.11% and 21.13%. The results of PCA and HCA showed that the characteristics of volatile organic compounds in the ethyl acetate fraction of rhizosphere soil under intercropping and single cropping models could be clearly divided into two categories，the screening results of potential differential components based on OPLS-DA analysis indicated that various components， such as dibutyl phthalate，（<italic>Z</italic>）-9-oleamide，<italic>β</italic>-caryophyllene，dioctyl iso-phthalate， phthalate （2-propylamyl） diester， <italic>n</italic>-hexadecane，octodecane， <italic>n</italic>-heneicosane， were screened from rhizosphere soil under the two models. Conclusion:The <italic>R. glutinosa-Z. mays</italic> intercropping model has certain effects on the volatile organic compounds in the rhizosphere soil of <italic>R. glutinosa</italic>，and the effect of the selected components on the growth and quality characteristics of <italic>R. glutinosa</italic> still need to be further studied.
ABSTRACT
Iridoid synthase( IS),the key enzyme in the natural biosynthesis of vegetal iridoids,catalyzes the irreversible cyclization of 10-oxogeranial to epi-iridodial. In this study,we screened the Rehmannia glutinosa transcriptome data by BLASTn with Catharanthus roseus CrIS cDNA,and found four c DNA fragments with length of 1 527,1 743,1 425,1 718 bp,named RgIS1,RgIS2,RgIS3 and RgIS4,respectively. Bioinformatics analysis revealed that the four iridoid synthase genes encoding proteins with 389-392 amino acid residues,protein molecular weights were between 44. 30-44. 74 k Da,and theoretical isoelectric points were between 5. 30 and 5. 87. Subcellular localization predictions showed that the four iridoid synthase were distributed in the cytoplasm. Structure analysis revealed that R. glutinosa iridoid synthases contain six conserved short-chain dehydrogenase/reductase( SDR) motifs,and their 3 D models were composed typical dinucleotide-binding " Rossmann" folds covered by helical C-terminal extensions. Using the amino acid sequences of four R. glutinosa iridoid synthases,phylogenetic analysis was performed,the result indicated that RgIS3,CrIS and Olea europaea OeIS were grouped together,the other R. glutinosa iridoid synthases and fifteen proteins in other plants had close relationship. Real-time fluorescent quantitative PCR revealed that RgIS1 and RgIS3 highly expressed in unfold leaves,however,RgIS2 and RgIS4 highly expressed in stems and tuberous roots,respectively. RgIS3 showed higher expression levels in non-radial striations( nRS) of the two cultivars,and RgIS1 and RgIS2 had higher expression levels in nRS of QH,while RgIS4 had less expression levels in nRS of QH1. RgIS1,RgIS2 and RgIS3 were up-regulated by Me JA treatment,although the time and degree of response differed. Our findings are helpful to reveal molecular function of R. glutinosa iridoid synthases and provide a clue for studing the molecular mechanism of iridoid biosynthesis.