Study On Rhizosphere Bacterial Diversity In Northern Tropical Seasonal Rain Forest Of Guangxi

The northern tropical seasonal rainforest of China was located in the south of Guangxi,which was one of the important types of forest vegetation distributed in the northern tropical region of China.It was a unique and huge treasure pool of biological diversity,due to different geological backgrounds,habitat types and monsoon climate.Under the unique geological background of the northern tropical seasonal rainforest in Guangxi,plants and microbes could evolve into a unique symbiotic relationship.As the microbial population played an important role in the cycle of rhizosphere nutrient elements and was an important biological medium for plants and soils,it made the study onrhizosphere microbial diversity in northern tropical seasonal rain forest important,especially bacterial diversity,which could enhance the understanding of the conservation mechanism of seasonal rainforests and provide reference for biodiversity conservation and ecological management.In this study,Nonggang National Nature Reserve and Fangcheng Yellow Camellia National Nature Reserve were used as research and the rhizosphere microorganisms of typical species were selected as the research objects.The high-throughput sequencing was carried out using the illumina hiseq 2500 sequencing platform,and the sequencing results were analyzed by using the R language combining the plant species,habitat types and soil physical and chemical properties.The effects of plant species and habitat types on the bacterial diversity of rhizosphere soils in the northern tropical karst seasonal rainforest were discussed.The effects of soil types and plant species on the bacterial diversity of rhizosphere soil in the northern tropical seasonal rainforest were also discussed.The main conclusions were as follows:First,both niche and plant species could have a significant effect on the composition of rhizosphere bacteria in the northern tropical karst seasonal rainforest,but the effect of niche on microbial communities was greater than that of plant species.Both soil types and plant species had a significant effect on the composition of rhizosphere bacteria in the northern tropical seasonal rainforest,but the effect of soil types on microbial community was greater than that of plant species.Compared with the influence of the karst seasonal rain forest niche on the composition of the rhizosphere bacterial community,the different soil types under different geological backgrounds had a greater effect on the composition of the rhizosphere bacterial community.With the change of soil type,the predominant bacteria were still Proteobacteria,Acidobacteria and Actinobacteria,and only the relative abundance of the Proteobacteria and Acidobacteria was significantly changed.PCoA analysis and cluster analysis showed that bacterial diversity in rhizosphere soil was mainly affected by habitat type factors,especially soil types.The soil type was the most important factor affecting the microbial community structure of plant rhizosphere.The reason for this phenomenon might be due to the soil type determined the soil physical and chemical properties,but also determined the rhizosphere environment pH,nutrient distribution and other important factors.In contrast,the effects of other habitat factors(such as elevation,etc.)and plant species are relatively smallSecond,based on the further analysis of soil physical and chemical properties and rhizosphere microbial community structure,we found that environmental factors closely related to soil types such as pH and water content were the main influencing factors of controlling the bacterial community structure in the rhizosphere of the northern tropical seasonal rain forest.Although the diversity of bacterial communities was affected by many other factors such as habitat types and plant species,but these differences could be explained by the soil physical and chemical properties,especially pHFinally,the plant species on the rhizosphere bacterial community composition still caused a certain impact.With the change of plant species,the biological markers of rhizosphere soil microbes would change.It was worth noting that rhizosphere microbiological markers of dominant plant species were often nitrogen-tolerant strains in soil environments with low nitrogen content.The same species of plants in different habitats would build a habit and function similar rhizosphere microbial community.The reason for this phenomenon might be that,plants changed their metabolic pathways under special environmental conditions to control the rhizosphere microorganisms and the rhizosphere microbial populations changed their metabolic pathways.Finally,the transformation of nutrient elements in the soil was improved,which was conducive to the growth of plants.Thus,when different plants were in similar habitats,plants that were adapted to the environment and had a beneficial relationship with rhizosphere microorganisms were more likely to become dominant species.In summary,in studying the plant diversity of the northern tropical seasonal rain forest,we should pay more attention to its rhizosphere soil type and physicochemical properties and its rhizosphere soil microbial community structure.In addition,the plant might be through the secretions and other ways to selectively adapt to rhizosphere microorganisms,in order to obtain the advantages of nitrogen and other characteristics.This would help the plant to get rid of the dilemma of the lack of nutrients in the niche and effectively use the resources and living space to expand the minimum threshold of habitat necessary for the survival and better adapt to the real niche.This adaptation mechanism was likely to be a decisive factor in determining whether a plant could be a dominant species and played an important role in the conservation of community.The adaptation mechanism would be of great significance to ecological restoration and agricultural production,and it was worthy of further study.