Integrated physiologic and proteomic analysis of Stropharia rugosoannulata mycelia in response to Cd stress

Soil Cd pollution seriously threatens environment and human health. Due to its ability to absorb and accumulate Cd in mycelia, Stropharia rugosoannulata could be a potential candidate for bioremediation of Cd-contaminated soils; however, the response mechanism of mycelia to Cd stress is still unclear. In this study, the physiologic and proteomic differences of S. rugosoannulata mycelia under 0.2 mg/L (low) and 2 mg/L (high) Cd stress were investigated. The results showed that Cd accumulation and mycelial growth inhibition exhibited a concentration-depended trend. Analysis of antioxidant system indicated that SOD, GR, GSH, GSSG and ASA played key roles in resisting the toxic effects of Cd. Via proteome analysis, 24 and 267 differentially expressed proteins (DEPs) were observed under low and high Cd stress, respectively. GO and KEGG analysis found that the mycelial growth inhibition might due to the down-regulation of some DEPs involved in "valine, leucine and isoleucine biosynthesis" and "tyrosine metabolism"; the certain tolerance to high Cd stress might attribute to the regulation of DEPs referred to energy metabolism and antioxidant system-related pathways, maintaining cellular energy homeostasis and removing ROS. These results provide a theoretical basis for further elucidation of response mechanisms in S. rugosoannulata to Cd stress.