© 2005 Heron Publishing—Victoria, Canada
Effects of two iron sources on iron and cadmium allocation in poplar (Populus alba) plants exposed to cadmium
F. Fodor (1, 2), L. Gáspár (1), F. Morales (3), Y. Gogorcena (3), J. J. Lucena (4), E. Cseh (1), K. Kröpfl (5), J. Abadía (3) and É. Sárvári (1)
1. Department of Plant Physiology, Eötvös University, Pázmány Péter sétány 1, H-1117, Budapest, Hungary / 2. Corresponding author (ffodor@ludens.elte.hu) / 3. Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas, Apdo.
202, E-50080, Zaragoza, Spain / 4. Departamento de Química Agrícola, Geología y Geoquímica, Universidad Autónoma de Madrid, E-28049 Madrid, Spain / 5. Chemical Technology and Environmental Chemistry, Eötvös University, Pázmány Péter sétány 1, H-1117, Budapest, Hungary / Received March 10, 2004; accepted December 17, 2004; published online July 4, 2005
Summary
Effects of 10 µM cadmium (supplied as Cd nitrate) on the utilization and allocation of iron (Fe) were investigated in poplar
(Populus alba L.) plants grown in nutrient solution with Fe(III)-EDTA or Fe(III)-citrate as the Fe source. The effects of Cd were also
compared with those of Fe deprivation. The accumulation of Fe in roots was 10-fold higher in plants grown with Fe-citrate
than with Fe-EDTA. Cadmium decreased leaf chlorophyll concentrations and photosynthetic rates, and these decreases were more
marked in plants grown with Fe-citrate than with Fe-EDTA. In both Fe treatments, addition of Cd caused large increases in
root and shoot apoplasmic and non-apoplasmic Cd contents and increases in root Fe content; however, Cd decreased shoot Fe
content, especially in plants grown with Fe-citrate. New leaves of plants grown with Fe-citrate had small cellular (non-apoplasmic)
Fe pools, whereas these pools were large in new leaves of plants grown with Fe-EDTA. Non-apoplasmic Cd pools in new leaves
were smaller in plants grown with Fe-citrate than with Fe-EDTA, indicating that inactivation of non-apoplasmic Cd pools is
facilitated more by Fe-EDTA than by Fe-citrate. In the presence of Cd, Fe-EDTA was also superior to Fe-citrate in maintaining
an adequate Fe supply to poplar shoots. Differences in plant responses to Fe-EDTA and Fe-citrate may reflect differences in
long-distance transport of Fe rather than in acquisition of Fe by roots.
Keywords:
cadmium toxicity, chelating agents, heavy metals, iron deficiency, nutrient solution.
