Lead and cadmium induced alterations of cellular functions in leaves of Alocasia macrorrhiza L. Schott

Alocasia macrorrhiza is a fast growing and propagating herbaceous species commonly found in South China. To determine its physiological responses to Pb and Cd stresses, the biochemical, histochemical and cytochemical changes under PbAC(2) and CdCl(2) phytotoxicity were detected using leaf discs as an experimental model. After leaf discs were infiltrated in different concentrations of PbAC2 and CdCl(2) solutions (0, 50, 100, 150, 200 mu M) for 72 h, the formation of reactive oxygen species (H(2)O(2)(-) and 01) in plant tissue were found to be exaggerated together with elevated center dot OH concentration and cell death. Changes in chlorophyll fluorescence (F(v)/F(m), Phi(PSII), qp and NPQ) imaging colours/areas of leaf discs indicated decreased photosystem II functions by both heavy metal treatments and positive reactions of antioxidants under Pb(2+) stress. Results showed that fluorescent detection of hydroxylated terephthlate using terephthalic acid as center dot OH trap is a simple, yet valuable and specific method for monitoring center dot OH generation in plant tissue under heavy metal stresses. As compared with Cd(2+), Pb(2+) was found to be less toxic, indicating that A. macrorrhiza tissue might have a potential tolerance to Pb. (C) 2010 Elsevier Inc. All rights reserved.