铜绿假单胞菌对龙葵中Cd的亚细胞分布和化学形态的影响

Effects of Pseudomonas aeruginosa on subcellular distribution and chemical speciation of Cd in Solanum nigrum

通过盆栽实验,研究Cd胁迫下铜绿假单胞菌对龙葵中Cd的亚细胞分布和化学形态的影响。盆栽实验中Cd浓度设为0、25、50、100 mg·kg^(-1),采用差速离心法、化学试剂逐步提取法对龙葵中的Cd进行亚细胞分布和化学形态研究。研究结果表明,接种铜绿假单胞菌处理中龙葵叶的Cd含量为未接种的1.14~1.60倍,促进植株中的Cd由根部向茎叶的转移。接种处理可提高根中细胞壁组分的Cd比例,及叶中可溶组分的Cd含量,降低植株根和叶中细胞器组分的Cd比例高达45.74%。此外,接种铜绿假单胞菌可提高龙葵叶中低活性形态Cd的比例。因此,接种铜绿假单胞菌可通过促进龙葵中Cd向地上部分的转移,改变植株中Cd的分布和形态比例,加强龙葵对Cd的耐受性。这些结果有助于重金属污染土壤中植物-微生物共生关系的进一步研究。

The effects of Pseudomonas aeruginosa on the distribution and chemical forms of Cd in Solanum nigrum were studied via a potting experiment. The concentration of Cd in the pot experiment was set at 0, 25, 50, and 100 mg·kg^（-1）. The subcellular distribution and chemical forms of Cd in Solanum nigrum were studied using differential centrifugation and stepwise extraction of chemical reagent. The results showed that the Cd content of Solanum nigrum leaves inoculated with Pseudomonas aeruginosa was 1.14-1.46 times higher than that of the non-inoculated leaves. Pseudomonas aeruginosa also promoted the transfer of Cd from roots to stems and leaves in the plants. Compared with the non-inoculation treatment, inoculation increased the Cd proportion in the cell wall of the roots and the Cd content in the soluble components of the leaves. In addition, inoculation decreased Cd uptake by up to 45.87% in the organelles of roots and leaves. Moreover,inoculation with Pseudomonas aeruginosa increased the proportion of low-activity Cd in the leaves of Solanum nigrum. Therefore, inoculation with Pseudomonas aeruginosa can promote the tolerance to Cd of Solanum nigrum by promoting the transfer of Cd to aboveground parts of the plant and changing the distribution and form ratio of Cd in the plant. These results will be beneficial for further studies on plant-microbe symbiosis in heavy-metal-contaminated soils.