Physiological and Proteomic Alterations in Macrocystis pyrifera under Chromium(VI) Stress

In order to further understanding of how alga are adjusted to chromium(VI) toxicity at the level of photosynthesis, the pigment content and chlorophyll a (Chla) fluorescence parameters, were studied in Macrocystis pyrifera blades treated with 0, 0.5, 2, 10 and 20 mg/L Cr (VI) solution for 24 h. Results showed that these parameters were clearly affected by different concentrations of Cr (VI The pigment contents and Chla fluorescence parameters were clearly decreased in M. pyrifera exposed to 20 mg/L Cr (VI). Furthermore, the present study provided novel insights into Cr(VI) toxicity at the proteomic level using TMT-based technology after M. pyrifera was irrigated with 0 or 20 mg/L Cr(VI) solution for 24 h. The decreases in pigment content and Chl a fluorescence parameters resulted from alternations of the related proteins involved in pigment synthesis and photosynthetic processes. Expression of 227 different proteins was detected. Analysis of significant changes in KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways showed that M. pyrifera is able to reorganize its proteome in favor of photosynthesis, carbon fixation, metabolic pathways, oxidative phosphorylation, biosynthesis of amino acids, carbon metabolism, ribosome and biosynthesis of secondary metabolites under Cr(VI) stress. These findings could provide valuable information to elucidate the mechanism of Cr(VI) toxicity in M. pyrifera.