Anatomical and physiological characteristics of tanner grass exposed to arsenic

Abstract

Phytoremediation is a biological process that stands out as an effective and economic alternative for the removal of toxic elements; however, its success depends on previous studies of plant species and the species’ tolerance of certain pollutants. The aim was at evaluating the anatomy and physiology of Tanner grass (Brachiaria arrecta) to determine its anatomical and physiological plasticity characteristics that potentially enable arsenic tolerance. B. arrecta plants were cultivated in a greenhouse in a Hoagland-Arnon nutritive solution with the following As concentrations: 0.0, 0.25, 0.5, 1.0, 2.0 and 4.0 mg L–1. Gas exchange, anatomical characteristics, DNA quantification and arsenic absorption were evaluated at 18 and 21 days. An evaluation of plant growth was conducted to compare the selected plants at the beginning and after 21 days of the experiment. The plants absorbed the arsenic contained in the solution and showed an increase in the leaf stomatal density, mesophyll and leaf blade thickness and root endodermis and exodermis, and the anatomical modifications showed no evidence of stress in the plant structure. The gas exchange, growth and DNA content were not modified by arsenic in B. arrecta plants. The B. arrecta plants have anatomical and physiological characteristics that contribute to their survival in the presence of arsenic, possibly helped by the tolerance of this species of arsenic contamination from the nutrient solution and the lack of anatomical and physiological changes resulting in damage to this species.