ABSTRACT
ObjectiveTo reveal the correlation of Rehmannia glutinosa-soil feedback process with the formation of its continuous cropping obstacles through the identification of the root exudates of R. glutinosa and analysis of the specific rhizomicrobes recruited by the root exudate. MethodThe root exudates of R. glutinosa seedlings germinated under sterilized condition and those enriched in the rhizosphere of R. glutinosa cultivated in the field were collected and analyzed using the ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry（UPLC-Q-TOF-MS）. The highly abundant compounds identified in the root exudates were added into blank soil， and the soil microbial community was profiled using Illumina Miseq sequencing. The bacterial and fungal functions were predicted by PICRUSt and FUNGuild， respectively. ResultThe identification results showed that seven phenylethanoid glycosides were found in R. glutinosa root exudates， and acteoside possessed the highest abundance. In the soil enriched with acteoside， the bacterial genera such as Agromyces， Pseudomonas， Lysobacter， Sphingobium， Pseudoxanthomonas and Sphingomonas were enriched. For the fungi， the genera Neocosmospora， Plectosphaerella and Dactylonectria， and the species such as Neocosmospora rubicola， Plectosphaerella cucumerina， Dactylonectria alcacerensis and Fusarium solani showed higher abundance. The functional analysis indicated the above-mentioned bacterial genera may realize rapid proliferation by utilizing， biodegrading and transforming phenylethanoid glycosides， and some potential fungal pathogens were colonized. ConclusionThe R. glutinsoa-soil feedbacks were likely generated by the phenylethanoid glycosides in the root exudates together with the specific rhizomicrobes. The investigations of R. glutinsoa-soil feedbacks under continuous cropping system are critical to the further understanding of the underlying mechanisms related to its continuous cropping obstacles.
ABSTRACT
ObjectiveTo study the composition of volatile oil in Opisthopappus taihangensis （Taihangju）， and provide a reference for comprehensive development of this medicine. MethodTaking Chrysanthemum morifolium （Xiaobaiju）， C. morifolium （Xiaohuangju） and C. indicum （Yejuhua） as control， the qualitative and quantitative analysis of volatile oil in Taihangju and three control varieties were completed by gas chromatography-mass spectrometry （GC-MS） combined with retention index method. The GC conditions were as following：programmed temperature （initial temperature at 60 ℃， kept for 2 min； up to 120 ℃ with the heating rate of 5 ℃·min-1， still kept for 2 min； up to 180 ℃ with the heating rate of 2 ℃·min-1， kept for 3 min； and then up to 240 ℃ with the heating rate of 8 ℃·min-1， kept for 5 min； finally up to 280 ℃ with the heating rate of 10 ℃·min-1， kept it for 5 min and finished）， high-purity helium as the carrier gas， the split ratio of 50∶1. MS conditions were as follows：electron impact ion source （EI）， ion source temperature of 230 ℃， electron collision energy of 70 eV and scanning range of m/z 30-445. Principal component analysis （PCA） and orthogonal partial least squares-discriminant analysis （OPLS-DA） were used to obtain the characteristic components between Taihangju and the three control varieties. ResultA total of 86， 96， 112 and 109 compounds including 73 common components were identified in Taihangju， Xiaobaiju， Xiaohuangju and Yejuhua， respectively. The contents of volatile components in Taihangju were significantly different from that of the control varieties. In which， the relative contents of α-thujone， eucalyptol and terpinen-4-ol were high in Taihangju， and eucalyptol， camphor and α-terpinyl acetate were the main compositions in the control varieties. In addition， 11 compounds were screened as characteristic components to distinguish Taihangju and the three control varieties by PCA and OPLS-DA， including main differential components of chamazulene and δ-cadinene. ConclusionThe main components of volatile oil in Taihangju includes alcohols， terpenes， ketones and esters with high medicinal value. The accuracy of qualitative analysis of volatile oil is improved by GC-MS combined with retention index method， which provides scientific reference for development and utilization of Taihangju.
ABSTRACT
This paper was aimed to explore the relationship between different commercial specification and chemical constituents on Radix Rehmanni,which provided experimental evidences for drawing up the commodity commercial specification and grading criteria of Radix Rehmanni.Several classified indexes,including grade,surface color,section color,section texture were carried to explore the change rules of chemical constituents by setting the contents of iridoid glycoside,sugars,water content,total ashes,acid-insoluble ashes and water extract as the markers.The results showed that the grade,surface color and section texture had less impact on chemical constituents.However,the section color had more influence.Along with the section color gradually being deepened,the contents of iridoid glycoside and oligosaccharides of Radix Rehmanni were lower,and the contents of monosaccharide and polysaccharide were higher.It was concluded that there was correlation between commercial specification and chemical constituents of Radix Rehmanni.