Arsenic stress effects on root water absorption in soybean plants: Physiological and morphological aspects

VEZZA, MARIANA E.; LLANES, ANALÍA; TRAVAGLIA, CLAUDIA; AGOSTINI, ELIZABETH; TALANO, MELINA A.

PLANT PHYSIOLOGY AND BIOCHEMISTRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Año: 2018 vol. 123 p. 8 - 17

0981-9428

Soybean (Glycine max L.) is often cultivated in areas contaminated with arsenic (As), which negatively affectsplant growth and reduces crop yield. The deleterious effects may be due, at least in part, to disturbances in thewater status, as was reported for some plants exposed to heavy metals. However, to our knowledge, thesemechanisms have not been studied in depth in soybean plants exposed to As. The aim of the present work was toanalyze possible changes in water relations and the responses developed in soybean plants under arsenate (AsV)and arsenite (AsIII) stress. We discuss physiological and morphological aspects of the As stress response, such asroot absorption rate, water content, stomatal conductance, water and osmotic potential, accumulation ofcompatible solutes, leaf conducting tissues and stomata characteristics. AsV and AsIII caused a significant decreasein root absorption rate, which could reduce metalloid uptake. On the other hand, water content decreasedat the beginning of the treatment but was re-established after 4 and 8 d. This was correlated with a decrease instomatal conductance and a reduction in leaf water and osmotic potential due to the accumulation of proline andsoluble sugars. Besides, smaller leaf xylem vessels and abnormal stomata were observed in plants under Astreatment. These mechanisms increased the plant´s ability to retain water and therefore to avoid dehydration.Thus, the results of the present work contribute to the understanding of how soybean responds to As, by describingkey tolerance strategies to the metalloid.