内生细菌抑制水稻镉吸收的分子生态机理研究

Cadmium (Cd) pollution causes significant threat to rice (Oryza sativa. L) production in China. Application of microoganisms, particularly the endophytic bacteria, in reducing Cd uptake in rice has attracted great attention. However, the mechanisms of how endophytic bacteria inhibit Cd uptake in rice are still not clear enough. In the present project, the rice will grow on Cd-contaminated soils in the pot experiments. The endophytic bacteria Pantoea sp. R3-3 and Stenotrophomonas sp. R5-5 that can inhibit rice Cd uptake will be inoculated to the pot soils. The effects of inoculation of endophytic bacteria on rice rhizosphere environment (Cd speciation and Fe/Mn plaque) will be studied. Meanwhile, the effects of endophytic bacteria inoculation on rhizosphere and endophytic microbial community will be investigated through 16S rDNA sequencing approach. The effects of inoculation of endophytic bacteria on the expression of ion transport genes will be revealed through combination of transcriptomic sequencing and RT-qPCR approaches. The aim of the project is to understand the link between the change in rhizosphere environment, endophytic microbial community and gene expression of rice and the Cd uptake in rice, and therefore, to reveal the molecular ecological mechanisms of how endophytic bacteria inhibit Cadmium uptake in rice. The project will offer a novel idea for the safe utilization of Cd polluted soils and theory supports for agricultural safety.

镉污染给我国的水稻生产造成了严重的威胁，利用微生物（特别是内生细菌）降低水稻镉吸收受到了广泛的关注。然而，对内生细菌抑制水稻镉吸收的机理仍缺乏系统的研究。本项目通过盆栽试验，在镉污染土壤中种植水稻，并接种可以降低水稻镉吸收的内生细菌Pantoea sp. R3-3和Stenotrophomonas sp. R5-5。分析接种内生细菌对水稻根际环境(镉形态和铁锰膜)的影响；同时，利用16S rDNA测序技术研究接种内生细菌对水稻根际和内生微生物群落的影响；结合转录组测序和定量PCR技术，阐明接种内生细菌对金属转运等功能基因表达的影响；揭示接种内生细菌引起的水稻根际环境、内生微生物群落和基因表达的变化与水稻镉吸收的关联性；最终解析内生细菌抑制水稻镉吸收的分子生态机理。该项目为镉污染农田的安全利用提供新思路，也为农业安全生产提供理论依据。

镉污染给我国的水稻生产造成了严重的威胁，利用微生物（特别是内生细菌）降低水稻镉吸收受到了广泛的关注。本项目通过盆栽试验，在镉污染土壤中种植水稻，并接种可以降低水稻镉吸收的内生细菌。分析接种内生细菌对水稻根际环境的影响，研究接种内生细菌对水稻根际和内生微生物群落的影响，阐明接种内生细菌对金属转运等功能基因表达的影响，揭示接种内生细菌抑制水稻镉吸收的内在机理。结果表明，内生细菌主要定殖与水稻茎叶中，可以有效抑制水稻镉的吸收，促进水稻的生长，改变水稻内生细菌群落。内生细菌抑制水稻镉吸收的机理包括信号传导和反馈调节两种。菌株能降低水稻根系铁锰膜的形成，促进必须养分的吸收，从而降低水稻镉转运蛋白基因OsNramp和OsHMA的表达，从而抑制水稻镉吸收；同时，内生细菌可能分泌一些信号分子，通过信号通路调节水稻转录因子如NAC和MYB的的表达，从而调控镉通道蛋白基因的表达。本研究为重金属污染治理和农业安全生产提供了思路和理论支撑。