生物质炭负载耐性菌强化东南景天吸收富集Cd的根际机制

我国农田土壤镉（Cd）污染问题日益突出。植物提取作为一种Cd污染土壤修复手段备受关注，然而其效率受到Cd有效性差及富集量小等限制。生物质炭负载耐性菌（BCM）能够促进植物提取Cd，但其强化机制目前尚不明确。本项目以生物质炭负载B. contaminans ZCC和东南景天为研究对象，从“BCM-根系”耦合关键根际过程切入，结合根际溶液监测、13C脉冲标记、DGT和宏基因组等技术，重点研究BCM对东南景天根系分泌物影响及其与根际Cd有效性的关系，探讨BCM介导下根际与Cd活化及吸收转运相关微生物及功能基因在植物吸收富集Cd中的作用，明确BCM对根际活性铝的钝化效应及其对植物吸收转运Cd的影响，以期从根系分泌物调控、根际（内）功能基因和根际活性Al等角度阐明BCM强化东南景天提取Cd机理。研究结果在理论上可揭示BCM强化植物提取的根际机制，在实践中可为Cd污染土壤植物提取强化提供新的技术手段。

Cadmium (Cd) pollution in agricultural soil is a serious problem in China. As a method of using plants to remove metals from soil, phytoextraction has attracted much attention due to low-cost and environment friendliness. However, numerous factors such as low Cd bioavailability in soil and small extraction amounts limit the efficiency of phytoextraction. Biochar loaded tolerant microorganism (BCM) could promote the accumulation of Cd by plants, but the mechanism of this enhancement remains not clear. In this study, biochar loaded B. contaminans ZCC and Sedum alfredii will be taken as research objects, and the "BCM root system" coupling rhizosphere process will be chosen as starting point. By using rhizosphere solution monitoring, 13C pulse labeling, DGT and Macrogenomic technology, we will investigate the mechanisms on: 1) the effects of BCM on root exudates of Sedum alfredii and its relationship with the availability of Cd in rhizosphere; 2) how the rhizosphere microorganisms and functional genes related to the activation, absorption and transport of Cd induced by BCM influence the uptake and accumulation of Cd by Sedum alfredii; 3) the passivation effects of BCM on active aluminum in rhizosphere and its effect on Cd uptake and transport by Sedum alfredii. The purpose of this study is to elucidate the mechanism of BCM enhancing Cd phytoextraction eficiency of Sedum alfredii in terms of root exudates regulation, rhizosphere functional genes and rhizosphere active Al passivation. The results of this study would reveal the rhizosphere mechanism of Cd uptake and accumulation in Sedum alfredii enhanced by tolerant bacteria loaded on biochar in theory, and provide new technical means for the assisted-phytoextraction of Cd contaminated soil in practice.