Study On The Micromorphology Of Leave Surface Particulate Matter And Leave Bacteria Community Structure Of Three Plants In Qingdao

Plant leaves are important filters for urban air pollutants,which can effectively prevent urban air pollution.phyllosphere microganism are a special component of plant leaf particles,which are not only closely related to host plants,but also have important ecological functions.Therefore,the characteristic of particles and microorganisms on leaf-surface have great significance to the near-surface.This study chose fresh leaves of Holly,Ligustrum and Cherry from different functional areas in Qingdao as the research object,analyze the number,size,type and seasonal and location changes of the retained particulate matter in plant leaves,as well as the micro-morphological characteristics,colonization characteristics and differences of leaf microbes;Illumina high-throughput sequencing technology based on 16S r RNA gene was used to explore the differences in the community composition,relative abundance,and structure of dominant bacteria in plant leaf bacteria in different seasons and locations.The following conclusions are obtained through research:(1)There were seasonal differences in the dust retained total amount of plant leaves.The total amount of TSP retained by the leaves of Holly,Ligustrum and Cherry plants was higher in autumn and winter than in spring and summer,and reached the highest in winter,and the total amount of dust retention by Cherry plant leaves was the highest in autumn.The total amount of retained PM₁₀ and PM_2.5 in the leaves of the three plant species was higher than the particles with D_p>10?m,mostly in the form of aggregates.The total amount of retained TSP and D_p>10?m particles in Holly leaves was the most among the three plants.The difference in the micro-morphological structure of plant leaves directly affects the total amount of particulate matter on the surface of plant leaves,among them,Holly was a small shrub with leathery leaves and jagged edges.The surface of the leaves was easy to absorb ground dust and automobile exhaust,and retain more particles with D_p>10?m;The surface of Ligustrum leaves was leathery,the edge was smooth,and adsorbed more particles with D_p<10?m;Cherry plant leaves were membranous and more likely to retain PM₁₀ and PM_2.5.Only the midribs had puberulent hairs and retained a small amount of D_p>10?m particles.In addition,Ligustrum and Cherry plants had higher trunks as tree plants,and the leaves were affected by wind.The particles on the leaf surface with D_p>10?m were easily blown away,and PM₁₀ and PM_2.5 were more likely to be retained.The retention of particles in plant leaves in different functional areas was significantly affected by the host plant's habitat.Urban arterial roads dued to higher concentrations of pollutants in the air,the total amount of retained TSP and D_p>10?m particles in plant leaves was higher than that in cultural and educational areas and urban parks,and was significantly affected by human activities.Plant leaves in cultural and educational areas and urban parks were more likely to retain PM₁₀ and PM_2.5.(2)The microbial community structure of Holly,Ligustrum and Cherry plant leaves was higher in autumn and winter than in spring and summer.Mycelium and fungal spores were more likely to appear on leaf surfaces in autumn and winter,and fungal spores were more suitable for low-temperature and dry environments.Plant leaves were easy to colonize different types of fungi,fungal spores and mycelium,and there were more spherical microorganisms.Fungi included yeasts,fungi with full or folded surfaces,etc.;spores included mold conidia,cladosporium conidia and chrysospores.In addition,different types of plants were also easy to retain unique microorganisms,Holly and Ligustrum tend to form translucent hyphae on the leaf surface and divided to form thick permanent spores.Fungal spores with evenly folds were detected on the leaf epidermis of Ligustrum,and because of its own characteristics.The relative abundance of phyllosphere microganism was the highest on leaves in urban park than that in urban main road and cultural district,and which showed that the humidity had a positive effect on the growth of microorganisms,and it was easier to find algae on the leaf surface.This was different from the particles on the surface of plant leaves,the colonization of microbes in the leaf area was not only affected by external conditions,but also by the microenvironment of the leaves area.There were many spherical fungi with concave surfaces in the leaf space of urban arterial road plants,which might be related to the high concentration of pollutant particles.(3)The results of?diversity analysis showed that the abundance of Holly and Cherry plant phyllosphere bacterial communities was the highest in spring and the lowest in summer,the abundance of leaf bacteria in Ligustrum was lower in summer and autumn.In addition,the abundance of dominant bacteria in the leaf area of plants was the lowest in summer and higher in spring.The characteristics of the phyllosphere of plants in spring were significantly different from other seasons.At the phylum level,Cyanobacteria had an absolute predominance in the phyllosphere bacterial community structure of plants in spring,while Proteobacteria was the dominant bacterial phyla in other seasonal plants.The dominant phyla bacteria of Holly,Ligustrum and Cherry plants were Proteobacteria,Cyanobacteria,Bacteroidetes,Actinobacteria,Firmicutes,Deinococcus-Thermus and Acidobacteria;The dominant bacteria classes mainly included?-Proteobacteria,Oxyphotobacteria,?-Proteobacteria,Bacteroidia and Actinobacteria,etc.;The dominant bacteria are Hymenobacter,Sphingomonas,Massilia,Acinetobacter,Pseudomonas and g??norank?f??Mitochondria.The phyllosphere bacterial of plants had host plant specificity,and had certain selectivity to host plants and the environment.Among them,the Proteobacteria of Holly,Ligustrum and Cherry plants leaves bacteria dominate at the phylum level;The dominant bacteria classes with higher relative abundance were?-Proteobacteria,?-Proteobacteria and Oxyphotobacteria;Sphingomonas and Massilia were in the plant leaf dominant genera The abundance accounted for relatively high.Plant leaf bacteria were significantly affected by the host plant's habitat.The diversity and dominant flora of Holly,Ligustrum and Cherry plants in the same functional area were similar.The abundance and diversity of bacterial communities in the leaf space of urban parks were higher than that in cultural and educational areas and urban arterial roads.Humidity could promote the growth and reproduction of bacteria in the leaf space of plants.