灰树粉孢菌对蓝莓磷素吸收的影响及作用机制研究

Blueberry always grows in acid soil, while there was little report about blueberry phosphorus deficient as the poor phosphorus availability in acid soil. We previous found that the oidiodendron was the dominant fungi in blueberry rhizosphere grown in Yangtze river basin, and Oidiodendron griseum was separated and identified from blueberry rhizosphere. Previous studies demonstrated Oidiodendron griseum could improve phosphorus absorption of rhododendron, indicating that Oidiodendron griseum might play a great role in blueberry phosphorus absorption. Therefore, blueberry phosphorus absorption of different parts and different development stages, influenced by Oidiodendron griseum, was investigated, revealing the effect of Oidiodendron griseum on blueberry phosphorus absorption. Then, effect of Oidiodendron griseum on soil phosphorus availability, forms, soil phosphorus transformation enzyme, and intensity of soil phosphorus transformation influenced was studied. And the absorption area and morphology of blueberry root influenced by Oidiodendron griseum was investigated. Secretion of phosphatase and plant hormones like auxin(IAA), gibberellin(GA) and cytokinin(CTK) was investigated in pure culture of Oidiodendron griseum. By 454 high-throughput gene sequencing technology and Biolog method, the colonization of Oidiodendron griseum in blueberry rhizosphere, the response of soil microbial community structure, diversity and function was studied. And then clarify the underlying regulation mechanism of Oidiodendron griseum on blueberry phosphorus absorption. The research achievements would provide a theoretical reference for understanding blueberry phosphorus absorption in acid soil.

蓝莓是典型喜酸植物，其在酸性低磷土壤上生长却鲜有磷素缺失报道，我们前期从蓝莓根际分离获得一株根际优势真菌-灰树粉孢菌（Oidiodendron griseum），已有报道该菌能促进杜鹃花磷素吸收，推测其在蓝莓磷素吸收方面起着重要作用。本项目首先通过研究灰树粉孢菌对蓝莓不同部位、各生育期磷素吸收影响，明确其调控蓝莓磷素吸收作用；深入探究灰树粉孢菌对土壤磷素形态、有效性及土壤酸性磷酸酶活性与土壤磷转化强度的作用；结合其对蓝莓根系生物量、吸收面积、吸收根总长的影响；同时分析灰树粉孢菌的生理代谢特性，包括磷酸酶与生长素、赤霉素、细胞分裂素等植物类激素分泌情况；并结合高通量基因测序和Biolog等技术探究其在蓝莓根际的定殖情况、对土壤微生物群落结构组成与功能的影响。以期从植物、土壤、微生物多个角度揭示灰树粉孢菌调控蓝莓磷素吸收作用机制。研究结果可为蓝莓适应酸性低磷土壤的磷素吸收机制提供新的科学认识。

蓝莓（Vaccinium spp.）是一类典型的喜酸植物，而在酸性土壤中磷素多以惰性状态存在而有效性较低，而已有研究表明蓝莓并不缺磷，我们在蓝莓根际分离到一株主要优势真菌灰树粉孢菌，猜测其在蓝莓磷素吸收高效利用方面起着重要作用。因此，本项目研究了灰树粉孢菌对蓝莓磷素吸收的影响，同时分析其对土壤磷素转化、自身生理代谢特征和对土壤微生物多样性群落结构与功能的影响，揭示其调控蓝莓磷素吸收的作用机制。.研究结果表明接种灰树粉孢菌会显著促进蓝莓各器官磷素的吸收，同时促进了蓝莓不同生育期叶片磷素的吸收，表明了灰树粉孢菌是蓝莓根际一类重要的功能微生物，能够调控促进蓝莓磷素吸收。.进一步土壤分析研究发现接种灰树粉孢菌后促进了土壤磷素的转化，提高了土壤有机磷和速效磷的含量，同时接种灰树粉孢菌后土壤酸性磷酸酶活性显著升高，且土壤无机磷和有机磷的转化强度分别显著增强，同时研究还发现接种灰树粉孢菌处理显著促进了蓝莓根系的生长，并增加了蓝莓根系总长度和总表面积，从而促进了蓝莓磷素的吸收。.对于灰树粉孢菌生理代谢特征研究发现，其并无分泌生长素（IAA）、赤霉素（GA）和细胞分裂素（CTK）等植物激素能力，同时在缺磷情况下也无分泌酸性磷酸酶现象。.灰树粉孢菌能够提高土壤微生物功能的发挥，同时其能在土壤中存活定殖，并且在蓝莓根际有显著性的定殖聚集性，研究结果表明灰树粉孢菌在蓝莓根际定向的大量聚集定殖，可能在促进蓝莓磷素吸收方面起了重要作用。.本项目研究表明灰树粉孢菌能够显著促进蓝莓磷素的吸收，其作用机制是通过调整蓝莓根际微生物群落结构，提高土壤磷素转化作用，提高土壤磷素的供应能力，同时促进蓝莓根系生长，进而促进蓝莓磷素的吸收。