The Impact Of Phosphorus Deficiency On The Bacterial Community Composition And Phosphorus Transformation Profilings In Rice Rhizosphere

Phosphorus(P)is one of the indispensable elements in agricultural production,the production of phosphate fertilizer consumes a large amount of phosphate resources,which is a non-renewable resource.Thus,the shortage of phosphorus resources may become an important limiting factor restricting agricultural sustainable development.Therefore,improving phosphorus utilization efficiency is of great importance for agricultural development.Rhizosphere microorganisms are important drivers of plant rhizosphere phosphorus conversion and play a vital role in regulating rhizosphere phosphorus availability,and they are also closely associated with plant phosphorus uptake.Therefore,understanding the mechanism of rhizosphere microbial community assembly and phosphorus transformation capacity under phosphorus deficiency is vital to improve phosphorus utilization.In this study,the changes of rhizosphere bacterial community composition,diversity,and phosphorus transformation capacity of rice rhizosphere under phosphorus deficiency were analyzed using high-throughput sequencing technology.The primary results are as follows:(1)Compared with +P treatment,-P treatment had a significant effect on rice growth.The aboveground height of rice under-P treatment was significantly reduced by 24.04%(P <0.05),and the root length was significantly increased by 26.50%(P < 0.05).At the same time,the aboveground fresh weight(SFW)and aboveground dry weight(SDW)of rice under-P treatment were significantly decreased by 60.62% and 55.83%(P < 0.05),respectively,while root fresh weight(RFW)and root dry weight(RDW)increased by 65.41% and 64.71%(P < 0.05),respectively.Phosphorus deficiency also changed rice root morphology.-P treatment significantly increased the root projection area,root surface area and total root tip number.On the contrary,the total phosphorus content in the upper part of rice under-P treatment was significantly reduced by 57.63%(P < 0.05).(2)Proteobacteria,Firmicutes,Desulfobacterota,Actinobacteriota,Chloroflexi,Acidobacteria,Bacteroidota,Verrucomicromycetes,Myxococcota,Planctomycetacia,and Nitrospirota are the dominant bacterial phyla in rice rhizosphere soil.-P treatment significantly changed the rhizosphere bacterial community composition.The relative abundance of Desulfobacterota,Verrucomicrobiota,Patescibacteria,Fibrobacteres,Cyanobacteria,and WPS-2 was significantly lower in-P treatment than in +P treatment,while the relative abundance of Proteobacteria,Bacteroidota,and Nitrospirota was significantly higher in-P treatment than in +P treatment.However,phosphorus deficiency little impact bacterial α diversity.(3)Under-P treatment,phosphorus-soluble bacterial taxa were enriched in rice rhizosphere soil,and the phosphorus-soluble ability of rice rhizosphere bacterial flora was significantly enhanced.The results of functional prediction(PICRUSt2)showed that the relative abundance of bacterial taxa with inorganic phosphorus solubilization functions(containing pqq B,pqq C,pqq D,and pqq E genes)was significantly higher in-P treatment than in +P treatment.Through incubation experiments,it was found that rice rhizosphere microorganisms had strong inorganic phosphorus(calcium phosphate)solubility ability,and it was significantly greater in-P treatment than in +P treatment,but the organic phosphate(lecithin)mineralization capacity of rhizosphere microorganisms was weak,and there was no significantly difference between-P and +P treatment.(4)Ten phosphorus-dissolving bacterial strains were isolated from rice rhizosphere soil,and they were preliminarily identified as Burkholderia seminalis and Paraburkholderia kururiensis.Further analysis showed that Paraburkholderia kururiensis was enriched in rice rhizosphere under-P treatment,but Burkholderia seminalis was dilutied under-P treatment,indicating the different response of phosphorus-dissolving strains to phosphorus deficiency and suggested that they may play different roles for rice in coping with phosphorus deficiency.In summary,the α diversity of bacterial community in rice rhizosphere did not significantly impacted by phosphorus deficiency,but bacterial community structure significantly changed under phosphorus deficiency.Rice rhizosphere bacterial community have strong inorganic phosphorus solubility capacity but low organic phosphorus mineralization capacity.Under phosphorus deficiency,the inorganic phosphorus dissolving ability of rhizosphere bacteria was significantly enhanced,while the mineralization capacity of organic phosphorus did not significantly change.These results indicate that selectively enriching phosphorus-soluble microorganisms in the rhizosphere may be an important way for rice to cope with phosphorus deficiency.