Physiological Ecology And Metabolomics Characteristics Of Ammopiptanthus Mongolicus In Its Adaptation To The Environmen

Ammopiptanthus mongolicus is an evergreen broad-leaved shrub living in cold plateaus and deserts.It belongs to the remnant species that survived the drought process of the shrinking climate of the ancient Mediterranean.As one of the dominant and constructive species of desert vegetation in northwest China,A.mongolicus plays an important role in maintaining the stability of the local ecosystem.A.mongolicus has strong drought and cold resistance.It is an ideal material for studying plant stress resistance and adaptability,and has high scientific research value.In this study,the A.population,which is naturally distributed among Otok Banner,West Ordos,Inner Mongolia,was used as the research object.Through a series of field experiments,such as measuring photosynthetic physiological indicators and chlorophyll fluorescence parameters,we studied the physiological and ecological characteristics of A.mongolicus of different ages under different seasonal environmental conditions.And we used non-targeted metabolomics technology to analyze the differential metabolite expression characteristics of leaves.The aim of this study is to combine physiology and metabolomics to explain the adaptation mechanism of A.mongolicus to desert environment from multiple perspectives and levels,and to provide scientific basis for plants to adapt to the environment of arid area and desert ecological restoration.The main findings are as follows:1.The vegetation composition and structure of A.mongolicus have the characteristics of seasonal variation,which is affected by habitat conditions.The survey results show that the A.mongolicus community is mainly composed of shrubs and herbs.The common shrubs belong to Leguminous and Tribulus terrestris and the herbs mainly belong to Compositae,Gramineae and Chenopodiaceae.Spring is the growing season of A.mongolicus,and its crown diameter and plant height increase significantly from April to July.In summer,the herb diversity of A.mongolicus community decreased.The age structure of A.mongolicus population is stable,and the number of young is slightly less than that of old.2.The photosynthetic physiological and ecological characteristics of A.mongolicus at different ages were different,and changed significantly with season and environmental conditions.The results showed that the middle-aged and young A.mongolicus were more sensitive to environmental changes.Affected by the severe drought in summer,its photosynthesis was less than that in spring.The photosynthesis of aged A.mongolicus in summer is greater than that in spring,and its adaptability to high temperature and drought environment is strong.Under the condition of high temperature and drought in summer,the photosynthesis of young A.mongolicus is mainly limited by non-stomatal factors,its photosynthetic structure and electron transfer are damaged greatly,and its carboxylation efficiency is reduced.Middleaged and old A.mongolicus are affected by both stomatal and non-stomatal factors.Their electron transfer rate and dark respiration rate decreased,the maximum carboxylation efficiency of old A.mongolicus increased,while that of middle-aged A.mongolicus decreased.In terms of energy utilization,A.mongolicus consumes the absorbed excess light energy in the form of heat dissipation to avoid the damage of reactive oxygen species to the photosynthetic system,while the energy used for photosynthesis is relatively reduced.3.The water physiological and ecological characteristics of A.mongolicus at different ages are different,and change significantly with season and environmental conditions.Under natural conditions,the transpiration of leaves of A.mongolicus at different ages in spring showed young age>middle age>old age;Under the influence of drought environment in summer,the transpiration of leaves of A.mongolicus at different ages showed aging>middle age>young age;Compared with spring,the transpiration of aged A.mongolicus increased in summer,the middle-aged and young A.mongolicus decreased.Under summer irrigation treatment,the transpiration of A.mongolicus increased significantly at three ages,while its water use efficiency decreased.The results showed that the transpiration of A.mongolicus was sensitive to the changes of rainfall and soil water conditions,and the transpiration and water use efficiency of young A.mongolicus were the largest.4.Affected by the natural environment,there are obvious seasonal characteristics in the differential expression of metabolites in the leaves of A.mongolicus at different ages.We used non targeted metabonomics to study the differential expression of metabolites in leaves of A.mongolicus in spring and summer under natural conditions.The results showed that most of the differential metabolites of A.mongolicus in spring and summer were related to metabolism,and about half of them were attributed to the biosynthesis of secondary metabolites.Differential metabolites related to genetic information processing are mainly attributed to"Aminoacyl-tRNA biosynthesis".The differential metabolites related to environmental information processing are mainly attributed to "plant hormone signal transduction" and "ABC transporters" pathway.Amino acids and their metabolomics related differential metabolites accounted for the largest proportion of the total metabolites,followed by benzene and substituted derivatives,aldehydes,ketones and esters related differential metabolites.Among different ages of A.mongolicus,the number of differential metabolites of young A.mongolicus was the largest,and the number of significant enrichment pathways of old A.mongolicus(P<0.05)was the largest."Linoleic acid metabolism","alpha-Linolenic acid metabolism","Arachidonic acid metabolism","Isoflavonoid biosynthesis" and "Flavonoid biosynthesis" were significantly enriched in the three age groups of A.mongolicus."Valine,leucine and isoleucine degradation",Valine,leucine and isoleucine biosynthesis" and"Aminoacyl-tRNA biosynthesis" metabolic pathways are unique and significant enrichment pathways of aged A.mongolicus,which may be related to the strong adaptability of aged A.mongolicus to summer environment.To sum up,this study analyzed the composition and structural characteristics of A.mongolicus community under different habitat conditions,and clarified the seasonal variation law of photosynthetic and water physiological ecology and metabolite differential expression of A.mongolicus at different ages.Our experiment provides some data support and scientific basis for further exploring the physiological and ecological response and adaptation mechanism of A.mongolicus under natural environmental conditions.