Lipid Profile Remodeling in Soybean Roots as a Response to Arsenic Stress

Arsenic (As) in groundwater and soils for soybean (Glycine max L.) irrigation and cultivation constitutes a major agronomic problem since the metalloid can be incorporated into plant tissues. Phospholipids (PL), and their constituent fatty acids (FA) are main components of cell membranes, so they are one of the biomolecules that firstly sense external conditions. Since the role of PL and FA in the response of soybean to As is unknown, our objective was to analyze possible changes in these molecules profiles in roots exposed to arsenate (AsV) and arsenite (AsIII). For that, PL and FA from soybean plants treated during 1 and 8 days with As-enriched solutions were analyzed by HPLC–MS/MS and GC–MS. A decrease in the relative amount of unsaturated FA together with an increase in saturated FA was found in roots exposed to both chemical forms of As compared to control condition. As a result, less unsaturated FA/saturated FA ratio and double bond index (DBI) occurred under exposure to As. Changes in PL composition were more evident after 8 d, including a decrease in the total content of phosphatidylethanolamine, with the consequent rise in the phosphatidylcholine/phosphatidylethanolamine ratio, and an increase in the total content of phosphatidic acid. This remodeling of PL and FA in soybean roots could be associated with a reduction in the fluidity and permeability of cell membranes, which would be a key aspect in the adaptive response of root tissue to As-stress.