Lead tolerance of water hyacinth (Eichhornia crassipes Mart. - Pontederiaceae) as defined by anatomical and physiological traits

Fabricio J Pereira,Cynthia De Oliveira,Valdemar Faquin,Silvio J Ramos,Evaristo M De Castro,Marinês F Pires,Marcio P Pereira

doi:10.1590/0001-3765201420140079

Fabricio J Pereira, Cynthia De Oliveira + Show 5 more

Open Access

https://doi.org/10.1590/0001-3765201420140079

Copy DOI

Abstract

This study aimed at verifying the lead tolerance of water hyacinth and at looking at consequent anatomical and physiological modifications. Water hyacinth plants were grown on nutrient solutions with five different lead concentrations: 0.00, 0.50, 1.00, 2.00 and 4.00 mg L-1 by 20 days. Photosynthesis, transpiration, stomatal conductance and the Ci/Ca rate were measured at the end of 15 days of experiment. At the end of the experiment, the anatomical modifications in the roots and leaves, and the activity of antioxidant system enzymes, were evaluated. Photosynthetic and Ci/Ca rates were both increased under all lead treatments. Leaf anatomy did not exhibit any evidence of toxicity effects, but showed modifications of the stomata and in the thickness of the palisade and spongy parenchyma in the presence of lead. Likewise, root anatomy did not exhibit any toxicity effects, but the xylem and phloem exhibited favorable modifications as well as increased apoplastic barriers. All antioxidant system enzymes exhibited increased activity in the leaves, and some modifications in roots, in the presence of lead. It is likely, therefore, that water hyacinth tolerance to lead is related to anatomical and physiological modifications such as increased photosynthesis and enhanced anatomical capacity for CO2 assimilation and water conductance.

Highlights

Environmental contamination by lead (Pb) is a worldwide problem (Gratão et al 2005)
We aimed to evaluate the lead tolerance of E. crassipes plants as related to modifications in its anatomy, gas exchange and antioxidant enzymes activities
Gas exchange characteristics in E. crassipes were modified by the lead treatments

Summary

Introduction

Environmental contamination by lead (Pb) is a worldwide problem (Gratão et al 2005). Lead is one of the most dangerous pollutants and its deposition in soil and water is related to effluents, fuels, industries and agronomical pesticides and fertilizers (Sharma and Dubey 2005).Traditional techniques for lead removal are expensive and often produce new dangerous effluents. Environmental contamination by lead (Pb) is a worldwide problem (Gratão et al 2005). Lead is one of the most dangerous pollutants and its deposition in soil and water is related to effluents, fuels, industries and agronomical pesticides and fertilizers (Sharma and Dubey 2005). Traditional techniques for lead removal are expensive and often produce new dangerous effluents. Phytoremediation is an alternative with low cost that has been utilized for soil and water decontamination (Gratão et al 2005, Rahman and Hasegawa 2011). Eichhornia crassipes showed a hyper-accumulation capacity for chromium (Faisal and Hasnain 2003), cadmium (Oliveira et al 2001) and arsenic (Dhankher et al 2002, Pereira et al 2011). The hyperacumulation capacity of this plant is related to its large biomass and the characteristics such as pH and temperature have little influence on the process (Schoenhals et al 2009)

Objectives

Methods

Results

Conclusion