School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China; Key Laboratory of Urban Agriculture, Ministry of Agriculture and Rural Areas, Shanghai Jiao Tong University, Shanghai 200240, China.
Shanghai Academy of Environmental Sciences, Shanghai 200233, China.
J Hazard Mater. 2023 Sep 5;457:131866. doi: 10.1016/j.jhazmat.2023.131866. Epub 2023 Jun 14.
The homeostasis regulating mechanism of endophyte enhancing cadmium (Cd) extraction by hyperaccumulator is poorly understood. Here, an endophyte strain E3 that belonged to Pseudomonas was screened from Cd hyperaccumulator Solanum nigrum L., which significantly improved the Cd phytoextraction efficiency of S. nigrum by 40.26%. The content and translocation factor of nutrient elements indicated that endophyte might regulate Cd accumulation by affecting the uptake and transport of magnesium and iron in S. nigrum. Gene transcriptional expression profile further revealed that SnMGT, SnIRT1, and SnIRT2, etc., were the key genes involved in the regulation of S. nigrum elements uptake by endophyte. However, changes in elemental homeostasis did not negatively affect plant growth. Endophyte inoculation promoted plant growth by fortifying photosynthesis as well as recruiting specific bacteria in S. nigrum endosphere, e.g., Pseudonocardiaceae, Halomonas. Notably, PICRUSt2 analysis and biochemical characterization jointly suggested that endophyte regulated starch degradation in S. nigrum leaves to maintain photosynthetic balance. Our results demonstrated that microecological characteristics of hyperaccumulator could be reshaped by endophyte, also the homeostasis regulation in endophyte enhanced hyperaccumulator Cd phytoextraction was significant.
内生菌增强超积累植物提取镉的体内稳态调控机制知之甚少。本研究从镉超积累植物龙葵中筛选到一株内生菌 E3，属于假单胞菌属，可显著提高龙葵对镉的植物提取效率 40.26%。营养元素含量和迁移因子表明，内生菌可能通过影响龙葵对镁和铁的吸收和运输来调节镉的积累。基因转录表达谱进一步表明，SnMGT、SnIRT1 和 SnIRT2 等是内生菌调节龙葵元素吸收的关键基因。然而，元素体内平衡的变化并没有对植物生长产生负面影响。内生菌接种通过增强光合作用以及在龙葵根内区招募特定细菌（如假诺卡氏菌科、盐单胞菌属）来促进植物生长。值得注意的是，PICRUSt2 分析和生化特性联合表明，内生菌调节龙葵叶片中淀粉的降解以维持光合作用的平衡。我们的研究结果表明，内生菌可以重塑超积累植物的微生态学特征，同时内生菌的体内稳态调节可以显著提高超积累植物对镉的植物提取。
