Study On The Effect Of Altitude On Metabolites Variation And Niche Prediction Of Cyclocarya Paliurus

Cyclocarya paliurus(Batal.)Iljinskaja is an endemic monophletic tree in China,which has founction of hypoglycemic,hypolipidemic,enhancing immunity.There are many factors that affect plant distribution in nature,altitude as a major topographic factor,has a significant effect on plant growth and development,the exploration of the influence of altitude on the content and composition of metabolites of C.paliurus and the prediction of the suitable distribution range of C.paliurus under climate change can provide the theoretical basis for the development and utilization of C.paliurus.The main results as follows:1.The contents of flavonoids and triterpenes in leaves of C.paliurus in high-altitude areas were significantly higher than those in low-altitude areas,while the content of polysaccharide in leaves of in C.paliurus low-altitude areas were significantly higher than those in high-altitude areas.The pathways of flavonoid synthesis were obtained from the results of metabonomics analysis.It was found that the effects of altitude on metabolites in leaves of C.paliurus were mainly on the flavonoid synthesis pathways,tryptophan pathways and the metabolic pathways of glycine,serine and threonine.Flavonoid synthesis pathway contained 18 different metabolites,among which the accumulation levels of 14 metabolites,including Chrysoeriol,Luteolin 6-C-glucoside,Chrysoeriol-7-glucoside,apigenin 5-O-glucoside,Apigenin C-glucoside,Kaempferide,Myricitrin,Naringenin C-hexoside,Naringenin 7-O-neohesperidoside,Tricetin,Tricin,Tricin O-rhamnoside,Tricin 4’-O-syringyl alcohol and Tricin O-sinapoylhexoside in leaves of C.paliurus were up-regulated,as the accumulation levels were significantly higher in high-altitude than in low-altitude.On the contrary,the accumulation levels of Chrysoeriol 5-O-hexoside,Astragalin,Naringenin O-malonylhexoside and Eriodictiol C-hexosyl-O-hexoside were dow-regulated,as the accumulation levels were significantly higher in leaves of C.paliurus from high-altitude than from low-altitude.2.A total of 732 differentially expressed genes were detected in leaves of C.paliuru in the high-altitude group and the low-altitude group,among which the expression levels of 91 genes were significantly up-regulated and 641 genes were significantly down-regulated in the high-altitude group.In the polysaccharide synthesis pathway,10 differentially expressed genes of glycosyltransferase belonged to the GT1,GT8,GH152,GH18 and CE10 families,respectively.In the terpene synthesis pathway,one differentially expressed gene tocopherol methyltransferase was screened.In the gibberellin A12 biosynthesis pathway,one differentially expressed gene enemy(EC: 5.5.1.13)was screened.In the flavonoids synthesis pathway,the amount of 8 enzyme coding gene expression including chalcone synthase(CHS),phenylalanine ammonia-lyase(PAL),flavonol synthase(FLS),chalconeisomerase(CHI),caffeoyl-Co A O-methyltransferase(CCOAOMT),4-coumarate--Co A ligase(4CL),shikimate O-hydroxycinnamoyltransferase(HCT)and flavonoid 3’-monooxygenase in leaves of C.paliurus at high altitude were up-regulated with different level,while the expression of flavonoid 3’,5’-hydroxylase(CYP75A)encoding genes was down-regulated.Through i TAK software,530 differentially expressed transcription factors were identified,of which the expression levels of 380 transcription factors in leaves of C.paliurus in high-altitudes was significantly lower than that those in low-altitude,but the expression levels of 150 transcription factors in leaves of C.paliurus in high-altitude was significantly higher than those in low-altitude.4 transcription factors of AP2/ERF family and 1 transcription factors of C2H2 family were related to the synthesis of polysaccharides in leaves of C.paliurus,respectively.4 transcription factors of MYB family were related to the synthesis of triterpenoids in leaves of C.paliurus.6 transcription factors of CHI families and 4 transcription factors of MYB families were related to the synthesis of flavonoids in leaves of C.paliurus.3.In this study,Max Ent model was used to screen the climatic factors and soil physicochemical factors.Eleven climatic factors and four soil physicochemical factors were selected.The AUC value and TSS value were used to evaluate the model.The AUC value was 0.979 and TSS value was 0.9556,indicating Max Ent model was effective.The suitable habitats for C. paliurus under three historical periods and two climate change contexts were predicted based on the information about 425 distribution areas of C.paliurus.The results of habitat suitability simulation of the glacial period,the middle Holocene period and the period from 1960 to 1990 showed that the high suitability area for C.paliurus in the three historical periods decreased with time,but the combined middle and high suitability area increased with time.According to the analysis of the distribution of suitable habitat under the two global warming scenarios of RCP2.6 and RCP8.5,the suitable habitat of C.paliurus decreases with the climate warming,indicating the distribution area of C.paliurus has a reduced tendency.