Arsenic toxicity in soybean seedlings and their attenuation mechanisms

ARMENDARIZ AL, TALANO MA, TRAVAGLIA C, REINOSO H, WEVAR OLLER AL, AGOSTINI E

PLANT PHYSIOLOGY AND BIOCHEMISTRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2016 vol. 98 p. 119 - 127

0981-9428

Even though vast areas contaminated with arsenic (As) are under soybean (Glycine max) cultivation, littleis known about the growth and intrinsic antioxidant metabolism of soybean in response to As exposure.Thus, an evaluation was carried out of plant growth, root anatomy, antioxidant system and photosyntheticpigment content under arsenate (AsV) and arsenite (AsIII) treatment. Soybean seedling growth wassignificantly affected at 25 mM or higher concentrations of AsV or AsIII, and the toxic effect on root growthwas associated with cell death of root tips. Microscopic analysis of cross-sections of As-treated rootshowed a reduction in the cortex area, dark deposits in cortex cells and broken cells in the outer layer.Similarly, in the vascular cylinder, dark deposits within xylem vessel elements and phloem cell wallswere observed. In all the analyzed parameters, the deleterious effect was more evident under AsIII thanAsV treatment. Arsenic-treated soybean seedlings showed increased activity of antioxidant enzymes[total peroxidases (Px) and superoxide dismutase (SOD)] in root and shoot harvested after 2 and 5 d oftreatment. However, a reduction in chlorophyll content and an increase in membrane lipids peroxidationwere observed. It is suggested that root structural alterations induced by As, such as the particularpattern of dark depositions in the vascular system, could be associated with an adaptation or detoxificationmechanism to prevent As translocation to the aboveground tissues.