镉胁迫对巴西蘑菇镉亚细胞分布和非蛋白巯基的影响

Effects of cadmium stress on cadmium subcellular distribution and non-protein thiol of Agaricus brasiliensis

本研究以不同浓度镉胁迫下的巴西蘑菇菌株J1(高Cd积累菌株)和J77(低Cd积累菌株)为实验材料,通过差速离心和酶联免疫法(ELISA),研究了菌丝生长、镉亚细胞分布、细胞内镉螯合相关的小分子非蛋白巯基化合物含量的变化以及小分子非蛋白巯基化合物代谢酶的活性,从细胞水平及酶学活性方面揭示了不同镉积累菌株对镉胁迫的响应机制。结果显示:随着外源添加镉浓度增加,2个菌株菌丝生长均受到抑制,出现大量气生菌丝,且J77气生菌丝多于J1;J1和J77菌丝中镉的分布规律均为细胞壁>细胞液>细胞器,表明细胞壁具有固持Cd^(2+)的作用;菌株J77中谷胱甘肽硫转移酶(GST)、谷胱甘肽过氧化物酶(GSH-Px)活性均高于J1;J77和J1中植物螯合肽(PCs)和非蛋白巯基(NPT)含量变化趋势一致,表现出“低促高抑”;相关性分析显示,镉胁迫与GSH-Px活性呈正相关关系,NPT含量与PCs含量呈极显著正相关。巴西蘑菇菌丝体镉解毒机制包括细胞壁沉积和重金属分区,非蛋白巯基物质的合成,不同菌株对镉胁迫响应存在差异。

In this study,Agaricus brasiliensis strains J1(high Cd-accumulating strain)and J77(low Cd-accumulating strain)under different concentrations of Cd stress were used as research materials.Using differential centrifugation and an enzyme-linked immunosorbent assay,we investigated the mycelial growth,Cd subcellular distribution,change in the content of small-molecule non protein thiol(NPT)compounds,and activity of small-molecule NPT compound-metabolizing enzymes that were related to intracellular Cd chelation,which revealed the response mechanisms of different Cd accumulating strains to Cd stress at the cellular level and enzymatic activity.The results showed that as the concentration of external Cd increased,the growth of the hyphae of the two strains was inhibited,and many aerial hyphae appeared.There were more aerial hyphae of J77 than that of J1.The distribution of Cd in the hyphae of J1 and J77 followed the order of cell wall>cell sap>organelles,which indicated that the cell wall could hold Cd^(2+).The activities of glutathione S transferase and glutathione peroxidase(GSH-Px)in strain J77 were higher than those in J1.The changes in the phytochelatin(PC)and NPT contents in J77 and J1 were consistent,and showed"stimulation at low Cd concentrations and inhibition at high Cd concentrations".Correlation analysis showed that Cd stress was positively correlated with the GSH-Px content,and the NPT content was significantly positively correlated with the PC content.The Cd detoxification mechanism of A.brasiliensis mycelium included cell wall deposition,heavy metal partitioning,and synthesis of NPT substances.Different strains exhibit different response patterns to Cd stress.