BIOREMEDIATION - Part II 

Minerva Biotecnologica 2001 June;13(2):141-9

Copyright © 2001 EDIZIONI MINERVA MEDICA

lingua: Inglese

Metal tolerance in wetland plants?

McCabe O. M., Baldwin J. L., Otte M. L.

Wetland Ecology Research Group, Department of Botany, University College Dublin, Belfield, Dublin, Ireland

Background. Metal tol­er­ance in non-wet­land ­plants may ­evolve fol­low­ing expo­sure to ele­vat­ed met­al con­cen­tra­tions, but ­this ­does not ­appear to be the ­case for wet­land ­plants. In pre­vi­ous stud­ies, no dif­fer­enc­es in met­al tol­er­ance ­were ­observed ­between pop­u­la­tions of Typha lat­i­fo­lia or Phragmites aus­tra­lis ­from met­al-con­tam­i­nat­ed and uncon­tam­i­nat­ed ­sites. In ­this ­study, ­zinc ­uptake and ­growth respons­es of pop­u­la­tions of the wet­land ­plant Glyceria flui­tans of met­al-con­tam­i­nat­ed (Glenda­lough) and uncon­tam­i­nat­ed ori­gin (Lough Dan) ­were com­pared. The ques­tion as to wheth­er or not met­al tol­er­ance is a con­stit­u­tive fea­ture of wet­land ­plants is ­addressed.
Methods. In green­house experi­ments, Glyceria flui­tans ­from Glendalough and Lough Dan ­were ­grown in (i) a ­range of ­zinc con­cen­tra­tions in ­zinc-amend­ed ­sand cul­ture and (ii) met­al ­enriched tail­ings. Growth, bio­mass and ­zinc ­uptake respons­es ­were com­pared ­between ­both pop­u­la­tions. A ­root elon­ga­tion ­test was ­also car­ried out to com­pare ­both pop­u­la­tions.
Results. When ­plants ­were ­grown on ­zinc-amend­ed ­sand cul­ture ­there was ­slight evi­dence for eco­typ­ic dif­fer­enc­es ­between pop­u­la­tions at the high­est ­zinc treat­ment ­only. There ­were no ­observed dif­fer­enc­es ­between pop­u­la­tions in the oth­er ­zinc treat­ments or ­when ­plants ­were ­grown on met­al-­enriched tail­ings. In the ­root elon­ga­tion ­test ­both pop­u­la­tions ­again ­appeared to be equal­ly tol­er­ant of ele­vat­ed ­zinc con­cen­tra­tions.
Conclusions. It ­appears ­that the pop­u­la­tions of G. flui­tans ­used in ­this ­study ­have not devel­oped ­zinc-tol­er­ant eco­types but ­have an inher­ent tol­er­ance to ­zinc. In ­light of ­this and oth­er stud­ies, met­al tol­er­ance may be a con­stit­u­tive fea­ture of wet­land ­plants.