Identification And Preliminary Study In Synthesis Mechanism Of Volatile Organic Compounds In Chrysanthemum And Wild Relatives

Chrysanthemum(Chrysanthemum morifolium,tribe Anthemideae,family Asteraceae)is one of 10 well-known traditional Chinese flowers.It is also one of the four most popular cut-flowers in the world.Plants are famous for their ability to produce a wide range of VOCs in flowers,leaves,fruits,and roots,where compounds are prepared and stored to be released immediately upon an attack.Floral scents have played important roles in the early evolution of flowers,and most are considered to be pleasant aromas by humans.There is a never-ending need to characterize and synthesize new aroma compounds.In this article,we compared the HIPVs between C.morifolium and Artemisia annua.We also identify the flower scent volatile compounds of chrysanthemum cultivars and their wild relatives,the main contents and conclusions are as follows:1.We analyzed the volatile organic compounds(VOCs)from Artemisia abrotanum L.leaves by use steam distillation,solvent extract and solid-phase microextraction(SPME).In solvent extract,we used n-hexane and methanol as extraction solvent which got different polarity.We got 39 compounds in steam distillation,23 compounds in n-hexane extract,and22 compounds in methanol extract,and 34compounds in SPME.200 g A.abrotanum leaves were used in steam distillation,we got 1.8 g essential oil,and the rate of oil production was0.9%.The main compounds in A.abrotanum leaves were boldenone,Eucalyptol,Germacrene D,and ?-Caryophylene.There were widely used in medical field and flavoring substances indurstry.2.We showed the effect of aphid infesting on the VOCs emitted by the infested Artemisia annua and C.morifolium cultivar 'Nan nong hong feng' plants by using headspace solid-phase microextraction(HS-SPME)method combined with gas chromatography mass spectrometry(GC-MS).In olfactometer bioassay experiment,aphids showed a preference for the odour of both healthy and infested chrysanthemum,while we found an opposite result in A.annua.Aphids tend to healthy plants compared with the infested,and the phenomenon became obvious with time.Different extracts were tested with the healthy plants and aphid infested plants.Eucalyptol,?-caryophyllene,(E)-?-farnesene,and germacrene D were released as the major constituents in both species.After aphid infesting,we observed a great increase in artemisia ketone and(E)-?-farnesene and a decrease in germacrene D in A.annua;comparatively,eucalyptol,isoborneol and?-caryophyllene increased in chrysanthemum.Combined with the GC-MS data and olfactometer bioassay results we concluded that(E)-?-farnesene and artemisia ketone emitted from A.annua might act as a potential volatile compound to resist aphids,and the two compounds would be useful for future ecological control of aphid in chrysanthemum cultivation.3.The objective of this study was to identify the major volatile compounds and their relative concentrations in flowers of different chrysanthemum cultivars and their wild relatives.The volatile organic components of fresh flowers were analyzed using a headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry.In total,193 volatile organic components were detected;the major scent components were monoterpenoids and oxygenated monoterpenoids,which accounted for 68.59%-99.93%of the total volatiles in all tested materials except for Chrysanthemum indicum collected from Huangshan,in which they accounted for only 37.45%of total volatiles.The major volatile compounds were camphor,a-pinene,chrysanthenone,safranal,myrcene,eucalyptol,2,4,5,6,7,7ab-hexahydro-1H-indene,verbenone,?-phellandrene and camphene.In a hierarchical cluster analysis,39 accessions of Chrysanthemum and its relatives formed six clusters based on their floral volatile compounds.In a principal component analysis,only spider type flowers were located closely on the score plot.The results of this study provide a basis for breeding chrysanthemum cultivars which desirable floral scents.4.We cloned 6 genes which encoded two Geranyl pyrophosphate synthase(GPPS),two 3-hydroxy-3-methylglutaryl-CoA reductase(HMGR)and two Farnesyl pyrophosphate synthase(FPPS).The 6 genes were named CmGPPSl.ssu,CmGPPS2.ssu,CmHMGRl,CmHMGR2,CmFPPS1,CmFPPS2.HMGR got two conservative regions,there were HMG-CoA binding domain and NADPH binding domain.FPPS got two conservative regions which were Aspartic acid-riched.Among 15 CmWRKYs in Chrysanthemun,CmWRKY2,CmWRKY7,CmWRKY8 and CmWRKY9 showed the similar expression pattern with the emitting of flower scent volatiles.AaWRKY1 in A.annua that regulates the biosynthesis of terpenes.CmWRKY7 and CmWRKY9 had high similarity to AaWRKY1.In Subcellular Localization experiment,CmWRKY7 were not only localized to the cell nucleus in onion epidermal cells,CmWRKY9 were localized to the nucleus.CmWRKY7got great transcriptional activation in yeast one-hybrid experiment,but CmWRKY9 had no transcriptional activation in yeast cell.