Effects Of Elevated CO₂ And Temperature On Physiology And Biosynthetic Pathway Of Phenolic Compounds In Ardisia Japonica Based On Metabolomics And Transcriptomics

Climate change is seriously threatening the sustainability of agricultural production and has become an important topic of research recently.However,there is surprisingly little experimental data demonstrate how elevated temperature and CO₂ will affect the growth of medicinal plants and secondary metabolites.Here,two different CO₂ concentrations [380 and 760 ?mol mol-1] were conducted on Ardisia japonica at two different temperature regimes of 23/18 oC and 28/23 oC?day/night?for 90 days.We used traditional physiology methods to comprehensively analyzed the effect of elevated CO₂ and temperature on photosynthetic process,biomass,antioxidant compounds,antioxidant capacity,and the balance of carbon and nitrogen compounds in the second fully expanded leaves of A.japonica.Plants metabolism and regulation have complex relationships.However,plants response to the changes of environmental factors in the regulation processes will not only effect a single metabolic pathway,but also change the balance of the whole metabolic network.Hence,the high through omics technologies could systematicly investigate plant physiological changes and would become a stronger potential tool to discover new genes.In this study,UPLC-Q-TOF/MS based metabolome,RNA-seq of transcriptome analysis,as well as the Interactive Principal Component Analysis?i PCA?,ANOVA-Simultaneous Component Analysis?ASCA?chemometrics methods analysis were performed to interpret the molecular mechanism of effects of climate change on carbon and secondary metabolism.Moreover,our study will provide a new insight on understanding the effects of climate change on the metabolic physiology of medical plants,which also play a vital role in promoting scientific.Our main results are as followed:Results showed that CO₂ level,temperature and their interaction had significant effects on leaf net CO₂ assimilation rates?AN?,stomatal conductance?gs?,transpiration rate?GH2O?,and intercellular CO₂ concentration?Ci?of A.japonica.Elevated CO₂ significantly increased the AN and accompany with the gs of leaves adaptability decreased.While higher ambient temperature decreased the AN,but its affects on Rubisco activity was non-significant.Elevated CO₂ and temperature significantly increased the Rubisco activity.Elevated ambient CO₂ level could effectively enhance the carboxylation capacity of Rubisco,restrain photorespiration and increase the net photosynthetic rate.When the ambient temperature was raised,the activity of Rubisco was inhibited and the carboxylation capacity of Rubisco was decreased.In our present study,no significant photosynthesis was observed during the 90-day cultivation of new leaves from emergence to maturity.Elevated ambient CO₂ level had obvious benefit of carbon gain,and increasing ambient temperature and CO₂ concentration had a positive effect on the accumulation of non-structural carbon in leaves.Plants are able to obtain more non-structural carbon effectively and provide more carbon skeletons for the downstream of secondary metabolites biosynthesis and increase the accumulation of flavonoids in leaves.Meanwhile,in this study,metabolomics and m RNA-seq techniques were used to obtain the genes and metabolites that responded significantly to ambient temperature,CO₂ level and their interactions.Temperature and CO₂ level can significantly affect carbon assimilation and gene expression in flavonoid biosynthetic pathways,which may alter the non-structural carbon content of plant leaves.Elevated ambient CO₂ level enhances energy metabolism and carbon metabolism,and photosynthesis fixes more carbon to provide more abundant carbon skeleton for the biosynthesis of secondary metabolites such as flavonoids.Overall,our data indicated that the predicted increase in atmospheric temperature and CO₂ could improve the biomass of A.japonica,but they would reduce its health-promoting properties.