Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : The Diversity and Ecological Function of Phyllosphere Epiphytes in the Extremely Arid Desert

Auteur : 刘加强

Grade : Master 2022

Université : Hebei University

Résumé
There are a large number of epiphytic microorganisms on the phyllosphere,which mainly include bacteria and fungi.The phyllosphere provides essential survival material and habitat for microorganisms,at the same time,the phyllosphere microorganisms can also promote plant growth,improve plant stress resistance,and prevent the occurrence of plant diseases.There are a variety of microorganisms in different environments,and in the same environment,each plant has abilities to screen and shape their phyllosphere microorganisms.However,the current studies are mostly focused on the phyllosphere epiphytes of plants in wetlands,farmland,forests,and other ecosystems,while there is a lack of systematic research on the phyllosphere epiphytes of desert plants.In this study,the epiphytic microorganisms of vegetation in extremely arid desert such as Sy.regelii,Sa.passerina,and N.sphaerocarpa were taken as the research objects.Through the combination of amplicon sequencing technology and isolation culture,the species of epiphytic communities and funtions in the phyllosphere of three plants were explored,and the effects of micromorphology on the diversity of epiphytic bacteria were explored by scanning electron microscope.The effects of different leaves physical and chemical properties on microbial community were revealed by measuring nutrients and water content in leaves.The main results are as follows:1.Epiphytic bacterial communities exist in the phyllosphere of extremely arid desert plants.A total of 492 OTUs were obtained by high-throughput sequencing,which were mainly composed of Actinobacteria,Firmicutes and Proteobacteria,and there were great differences in epiphytic bacterial communities among different plants.Stochastic and deterministic analysis of epiphytic bacterial community in the phyllosphere of three plants showed that the assembly of bacterial communities in the phyllosphere of Sa.passerina and Sy.Regelii is mainly controlled by the process of deterministic environmental filtration,while the assembly process of bacterial communities in the phyllosphere of N.sphaerocarpa is affected by environmental filtration,but it is conducive to the formation of different species ;There are complex interactions in the community of epiphytic bacteria,and their ecological functions mainly include chemoheterotrophy（39.02%）and aerobic chemoheterotrophy（37.01%）.2.The phyllosphere epiphytic fungal sequences were clustered into 115 OTUs,which were mainly composed of Ascomycota and Basidiomycota.There were great differences in the community of epiphytic fungi in different plants.Among them,the maximum number of epiphytic fungi in Sa.passerine was 48,and the minimum number of epiphytic fungi in Sy.regelii was 38.The vegetative types of epiphytic fungi can be divided into three categories,mainly saprophytic and pathological vegetative types,and their functions mainly include plant pathogen and undefined saprotroph.3.The culturable epiphytic bacteria of 10 genera,12 species and epiphytic fungi of 18 genera,23 species were isolated and identified from three plants.The main functions of culturable epiphytic bacteria are chemoheterotrophy and aerobic chemoheterotrophy,parts of bacteria have the ability to degrade lignin ;culturable epiphytic fungi are mainly saprophytic and pathotrophic vegetative type,and their functions are mainly plant pathogen and undefined saprotroph.4.The interception ability of three plants’ phyllosphere to environmental particulate matter and microorganisms is different,especially the interception ability of Sa.passerine is the most powerful ;Plant species affect leaf nutrients and water content,the nutrients and water content affect epiphytic alpha diversity,and water is the main factor ;plant species affect the leaf organic matter content,and then affect phyllosphere epiphytic colonies through water and nitrogen elements

Mots clés : The extremely arid desert ;Phyllosphere epiphytes ;Ecological function ;Sy.regelii ;Sa.passerine ;N.sphaerocarpa ;

Présentation (CNKI)