磷铝耦合条件下油茶根系分泌有机酸及其对磷铝吸收的影响机制

Phosphorus deficiency and high content of aluminum in acid soil are usually concerned as the important factors that severely limit the growth and production of Camellia Oleifera, which is one of important woody edible oil species in China. Previous studies showed that application of Al-P promote oiltea’s growth effectively; Phosphorus deficiency significantly induced the secretion of organic acids from roots such as citric acid, which release phosphorus from Al-P and other insoluble phosphate. However, it is unclear about the difference of organic acids secreted by roots of C. Oleifera under aluminum-phosphorus interactions and the relationship between super accumulation of aluminum and the activation of Al-P by organic acids induced. In this research, Phosphorus, aluminum and aluminum-phosphorus coupling stress experiment will be conducted on oiltea varieties with different phosphorus-use efficiency though simulation test of phosphorus activation and aluminum chelation, absorbtion kinetics in roots and related technologies. Our team will compare the difference of organic acids secretion of roots, uptake of aluminum and phosphorus and plant growth. Typical secretion features of organic acids from roots under phosphorus, aluminum and phosphorus-aluminum treatment will also be analyzed and its ability of solubilizing sparing soluble phosphate and chelating aluminum will be determined. It will be clarify whether the chelated aluminum and solubled phosphorus are uptake cooperatively and the relationship between phosphorus-use efficiency and aluminum-tolerance of oiltea, in order to understand the effect of phosphorus-aluminum interaction on secretion of organic acids from roots and uptake of aluminumand phosphorus, and accumulate data for revealing the mechanism of tolerance to low phosphorus and super accumulation of aluminum of C.Oleifera. This research will not only provide theoretical guidance for improving the utilization efficiency of phosphorus, but also has important implications for basic research in the frontier areas of plant adaptation mechanisms to acid soil.

油茶是我国重要木本食用油料树种，酸性土壤磷缺乏和铝含量高是影响其生长结实的重要因素。项目组前期研究表明施用Al-P有效促进油茶生长，柠檬酸等根系分泌有机酸显著受低磷诱导，并有效溶解Al-P。但磷、铝诱导油茶根系分泌有机酸的差异，以及其对Al-P的活化是否与油茶铝超积累有关还不清楚。本项目以不同磷效率油茶品种为材料，采用磷活化和铝螯合模拟试验、根系吸收动力学等技术手段，比较磷、铝及二者耦合条件下油茶根系有机酸分泌、磷铝吸收以及生长等方面的差异，分析不同处理诱导根系有机酸的分泌特征，确定诱导分泌有机酸磷活化和铝螯合能力，探讨活化磷和螯合铝是否存在协同吸收，明晰磷利用效率与铝忍耐能力之间的关系，以期阐明磷铝耦合条件下油茶根系有机酸的分泌特征及其对磷铝吸收的影响，为揭示油茶耐低磷和铝超累积机理积累资料。本项目不仅为提高油茶磷利用效率提供理论指导，而且在酸性土壤植物适应机理的基础研究上也具重要意义。

油茶是我国重要木本食用油料树种，酸性土壤磷缺乏和铝含量高是影响其生长结实的重要因素。前期研究表明，油茶是耐低磷和铝超累积植物，因此研究油茶对红壤区低磷高铝环境的适应机理具有重要意义。本研究对湖南省红壤区油茶林地土壤不同层次无机磷的组成、土壤铝的分级、油茶叶片磷铝含量等进行了分析，比较了根际与非根际土壤的磷、铝组成，分析了树体磷铝含量同土壤磷铝含量和分级的关系。在此基础上，开展了不同栽培措施条件下、不同磷源施用对油茶生长结实及土壤磷素形态等方面的影响研究；测定了不同磷、铝以及二者耦合条件下油茶形态、磷、铝含量等指标，比较分析了不同磷、铝梯度以及二者耦合条件下油茶根系形态、根系分泌物的成分变化规律；继续开展了磷、铝活化模拟试验；研究结果表明铝是油茶的有益元素，初步确定了磷、铝耦合条件下柠檬酸的特征分泌以及柠檬酸在油茶对Al-P形式的有效利用中的作用。此外，还开展了不同山茶属植物叶片铝积累特征、油茶磷高效转运蛋白、耐铝基因的克隆与表达分析等工作，为探索油茶适应低磷高铝环境机理做了有益的探索。同时，项目组还研发《一种土壤活化剂及其制备方法和应用》，该土壤活化剂能够活化土壤养分，减少酸性土壤中的铝毒，推动了科技成果应用于生产。在项目执行期间，在中文核心刊物以上发表学术论文 6 篇，其中在 SCI （ESI农业科学）收录源刊发表学术论文 2 篇，核心期刊4篇；接收CSCD收录期刊2篇，投稿SCI（ESI农业科学）收录源刊1篇；申请发明专利 1 项；培养硕士研究生1名，本科生5名。