大豆根际磷素转化相关功能微生物类群及其对植物磷素吸收的影响研究

Phosphorus is a necessary nutritional element for plant growth. It also plays an important role in the rhizobia and leguminous plants (such as soybean) symbiotic nodulation. Researchers suggested that some microorganisms could accelerate the decomposition of phosphorus in rhizosphere region and improve the plant phosphorus acquisition. But, so far at least, our knowledges about the structure and succession rule of functional microbial group which can promote the transformation of phosphorus in rhizosphere are very pool. As a result, there are very few studies trying to test and verify the abilities of these functional microorganisms to decompose different forms of phosphorus in rhizosphere, and very few studies can describe the whole process of these functional microorganisms to promote the plant growth and nodulation by increasing the phosphorus decomposition and supplement for plant. In this study, we will carry out some greenhouse plant cultivation experiments, using high-throughput sequencing and isotopic tracer technique, to reveal the composition and structure of functional microbial group which are connected with the phosphorus transformation in the soybean rhizosphere region, to analyze the influences of soil and plant factors on the composition, structure and succession rule of the functional microbial group, to verify the abilities of the functional microbial group to decompose different forms of phosphorus, to explore the process of plant absorbing and using these phosphorus. In the end, we will clarify the phosphorus transformation process led by the functional microbial group in soybean rhizosphere and its influences on the soybean plant growth and nodulation comprehensively and systematically.

磷素是植物生长所必需的营养元素，其在大豆等豆科植物的共生结瘤过程中也有重要作用。尽管研究者认为根际微生物能通过溶磷作用促进植物对磷素的吸收，但目前人们对在根际区域参与了磷素转化过程的主要功能微生物类群的结构和演替规律知之甚少，也无法检测和验证该功能微生物类群对不同形态磷素的矿化分解能力，因此也就不能准确地描述根际微生物通过对磷素的分解，来提高磷素供给量，进而促进豆科植物生长和结瘤固氮的详细过程。本项目拟通过温室植物栽培试验，应用高通量测序和同位素示踪等技术手段，揭示在大豆根际区域分布的与磷素形态转化相关的功能微生物类群的组成和结构，分析土壤和植物等因素对该功能微生物类群组成、结构和演替过程的影响，验证该功能微生物类群对不同形态磷素的矿化分解能力，明确这些磷素被分解后的吸收和利用过程，全面系统地阐明由根际功能微生物参与的磷素转化过程及其对大豆生长和结瘤的影响。

磷是重要的植物营养物质，尽管土壤中磷的总量庞大，但可被植物直接利用的有效磷含量较少，往往成为植物生长的限制性因素。很多研究表明植物能通过根际效应招募特定的微生物类群，其中就有大量解磷功能微生物，这些解磷微生物能参与磷素转化，提升根际区域磷的可给性，促进植物对磷素吸收。但目前该领域的研究多集中于纯培养菌株在实验室环境中解磷能力的测定上，而对于解磷微生物群体在原位环境中的构建过程及其参与磷形态转化的实际能力知之甚少，更不清楚微生物解磷作用与植物解磷作用的关系，因此无法准确地描述根际微生物通过磷的溶解和矿化提高磷素供给量，促进植物生长的详细过程。本项目通过温室植物栽培试验，分析了大豆根际区域磷素转化相关功能微生物类群的组成、结构和演替过程，探讨了土壤和植物因素对大豆根际区域磷素转化相关功能微生物类群的影响，以及功能微生物类群所介导的根际区域不同形态磷素矿化分解及吸收过程等问题。结果表明大豆根际微生物群落的构建受地域土壤特征和植物生长时期等因素的影响，其解磷功能与土壤本身的有效磷含量密切相关。对于有效磷含量较低的土壤，植物对根际微生物群落的塑造是加强该区域磷形态转化的有效手段，这种塑造过程对细菌群落影响更大。在根际区域，无论真菌还是细菌都更多地通过有机磷矿化作用提高根际有效磷含量，而无机磷溶解可能更多地与植物解磷作用有关。本项目的研究结果有助于对大豆根际微生物群落，特别是解磷微生物类群构建方式及其生态功能的理解，为更好地调控和利用这些功能微生物提供了理论支持和指导。