根内外微生物协同调控水稻镉积累的机理研究

In recent years, the "cadmium rice” influence people's health which is becoming serious accidents problem. And the endophytes in rice roots and soil microorganisms are closely interrelated with the rice which play a positive role in synergistic rice tolerance of cadmium stress and transfer, but the response and transport mechanism of soil microorganisms and plant endophytes to soil heavy metal pollution stress as an important basic science problem in soil biology is still unclear. In the preliminary study, we found that affect cadmium accumulation in plants by the directed screening compound flora, which could transform the morphology of cadmium in soil. So, to further explore the mechanism of the synergistic response of endophytes and plants to cadmium stress and cadmium transport, We studied the low-cadmium rice which grow in paddy fields with different cadmium concentrations in different cadmium accumulation levels, to clarify the community composition of bacterium and fungi in and out of rice roots. Using the16S rRNA, ITS and metagenomic sequencing identified the key species and their important functional genes affecting cadmium accumulation in rice, and analysis the effects of environmental physicochemical factors and agronomic traits of rice on microbial communities. Based on the results, we finally verify the rice endophytes response mechanism of cadmium stress and transfer at the genetic level by some laboratory experiments, such as strains isolation, functional genes expression. This project will be obtaining the key strains which participate in the cadmium accumulation in rice, and to provide scientific basis for more accurate and effective prevention and control of cadmium pollution in rice.

“镉大米”严重威胁了人民的食用安全，是亟待解决的科学和民生难题。水稻根部内生菌与土壤微生物在协同水稻耐受镉胁迫和镉转运方面发挥重要作用，但其对土壤重金属污染胁迫的应答和转运机制尚不明确。申请人在前期研究中发现定向筛选、复配构建的人工菌群可转化土壤中镉的形态，进而影响了植物体内的镉积累。为进一步探明内生菌与植物协同应答镉污染胁迫和镉转运的作用机理，选用常规低镉积累水稻品种为研究对象，解析在不同镉污染程度稻田的水稻根内、根外细菌和真菌的群落组成，通过宏基因组学测序鉴定识别影响水稻镉积累的关键菌株及重要功能基因，揭示环境理化因子和水稻农艺性状对微生物群落的影响机理。继而结合菌株筛选和功能鉴定试验，从分子水平上验证微生物协同水稻应答镉污染胁迫和镉转运的机制。本项目将为利用微生物协同调控作物重金属积累，更加准确有效防控水稻镉污染提供科学依据。

针对我国耕地重金属污染的严峻形势与粮食安全生产的迫切需求，课题以探明镉污染稻田土壤微生物与不同镉积累水稻根内外微生物群落协同水稻耐受重金属污染胁迫的应答和转运机制为研究目标。通过调查研究，探明了不同镉污染程度农田生态系统的细菌群落组成及其功能对陡峭镉梯度的生态响应，揭示了镉污染稻田的土壤性质和微生物群落对耕作层和犁底层镉形态分布的响应机制，利用比较转录组学分析方法阐明了高/低镉积累水稻品种对根系镉胁迫的响应机理，分析了不同镉累积品种的水稻根际细菌群落与土壤镉形态及根表铁膜性质的关联性，解析了不同镉累积早/晚稻品种根际细菌影响镉在土壤—水稻系统中的迁移累积机理。继而结合菌株筛选和功能鉴定试验，筛选得到了假单胞菌（Pseudomonas sp.）Z-12、粪产碱杆菌（Alcaligenes faecalis）DY-8和淡紫紫孢菌（Purpureocillium lilacinum N1）等介导土壤镉形态转化和促进植物镉积累的功能菌种。进一步通过开展室内盆栽试验研究水稻根内生菌群落和根内外关键细菌协同驱动稻米镉累积的作用机理，以及功能微生物影响土壤镉形态转化与植物镉积累的作用机制。相关研究数据发表SCI论文7篇，其中第一标注4篇；申请菌种资源专利3件，其中2件已获得国家发明专利授权；协助培养博士研究生3名。本项目将为利用镉形态转化和促镉积累的功能微生物协同调控作物重金属积累，有效防控水稻镉污染提供科学依据，同时也从环境微生物学视角为如何实现稻田土壤结合态镉的活化和永久性移除提供了新的解决思路。