Relationship Between Microbial Diversity And Plant Functional Traits In Rhododendron Communities Along An Elevation Gradient In Southwestern Mountains

Climate change is shifting the distribution,diversity and community composition of plants and microbes,and have a profound impact on the interactions between plants and microbes.As an important part of the ecosystem,microbe have a large impact on the growth and development of plants and the ecosystem function.However,we know little about the effects of changing in temperature and rainfall patterns on the interactions between plants and microbes and ecosystem functions.Thus,studies of the impact of climate change on plant-microbe interactions can help us to predict the consequences of climate change for plant-microbe interactions and ecosystem functions.As a crucial component of alpine and subalpine vegetation,Rhododendron plays an important role in the ecosystem.Herein,we examined the soil and root bacterial and fungal diversity,richness and community compositions in 11 Rhododendron communities along the elevation gradient through high-throughput sequencing technologies.Meanwhile,we used Pearson correlation,steppage-regression model,redundancy analysis and variance partitioning analysis methods to explore the main influencing factors of microbe diversity and species composition.Finally,we discussed the relationship among microbe,plant and ecosystem functions.The main research results are as following:(1)The bacterial and fungal diversity and richness in soil and root varied among three elevation gradients.The soil and root bacterial diversity and richness and diversity of soil fungal are apparent in mid-dominant effects.However,the abundance of soil fungal showed a decreasing trend with the rising of the elevation,and root fungal diversity and richness didn't show the obvious trend with elevation gradients.(2)The dominant species of soil bacterial are Proteobacteria,Acidobacteriota,Chloroflexi,Actinobacteriota and Verrucomicrobiota in three elevation gradients.The dominant species of root bacterial were Actinobacteria and Proteobacteria.The dominant species of soil and root fungal were Ascomycota and Basidiomycota,and the abundance of those dominant species differed among the three elevations.The abundance of Proteobacteria and Acidobacteriota of soil bacteria was higher at high elevation.Chloroflexi,Actinobacteriota and Verrucomicrobiota have higher abundance at middle and low elevations.The abundance of Proteobacteria of root bacterial was higher at middle elevation,while the abundance of Actinobacteriota was higher at low elevation.The abundance of soil and root fungal Ascomycota was higher at high and middle elevations,the abundance of Basidiomycota is higher at lower elevation(3)The diversity and community composition of soil and root bacterial and fungal were affected by soil attributes and climate factors.p H,MAT and MAP significantly affected the diversity of soil bacterial and fungal at middle and low elevations,but not at high elevation.C/N,MAT and MAP significantly affected the diversity of root fungal at low elevation.The diversity of soil,root bacterial and fungal were significantly correlated with soil and climate factors at lower elevation.Soil,climate and altitudinal gradient factors common influenced the composition of bacterial and fungal communities,and soil factors explain more than climate and altitudinal gradient factors.The stronger relationship between the species composition of soil bacterial and fungal and soil and climate factors,and the relationship between each species and environmental factors were observed at low elevations.However,only a few species of root bacterial and fungal had significant relationship with environmental factors.(4)Microbe diversity is an important factor affecting plant functional traits in Rhododendron communities.It mainly affects leaf total phosphorus content and the specific leaf area of plants at high and middle elevation,respectively.Furthermore,microbe diversity has the significant effect on leaf total nitrogen,leaf total phosphorus,specific leaf area and leaf dry matter content at the low elevation.In addition,the relationship between the microbe diversity and ecosystem multifunctionality index varied among three elevations.The climate factors and microbe diversity could provide more explanation on the difference of ecosystem multifunctional index at low elevation(69%).Thus,we speculate that the significant relationship between microbe diversity and ecosystem multifunctionality index at low elevations may be regulated by climatic factors.In summary,the soil and root microbe diversity varied among three elevations,and soil bacterial,fungal and root bacterial diversity showed significant mid-dominant effects in Rhododendron communities.Soil attributes and climate factors significantly affect the soil and root microbe diversity and community composition.Microbe diversity significantly affect the plant functional traits and ecosystem functions,especially at low elevation.The present study can not only facilitate our understanding on the biological diversity maintaining mechanism in Rhododendron communities,but also provide a scientific basis for the protection and management of the southwest plateau mountain ecological system.