Enhanced lead accumulation in Sesbania drummondii by plant hormones

摘要

The effect of plant growth hormones [indole-3-acetic acid (IAA) and naphthalene acetic acid (NAA)] in the presence of ethyl-enediaminetetraacetic acid (EDTA) on growth and lead (Pb) uptake was studied in Sesbania drummondii. Plant growth was significantly inhibited at the treatments containing Pb+EDTA, and EDTA with lower concentrations (up to 10M) of IAA and NAA. At high concentration (100M) of IAA and NAA, growth was comparable to control plants (grown in the presence of Pb only). The F<,v>/F<,m> and F<,v>/F<,0> values of treated seedlings remained unaffected, indicating normal photosynthetic efficiency and strength in the presence of EDTA and IAA or NAA. Pb uptake in plant tissue was significantly enhanced in the presence of EDTA supplemented with IAA or NAA. Addition of EDTA in growth media increased Pb uptake in shoots by 350% as compared to control plants. However, when EDTA was added along with 100M IAA and NAA, Pb uptake increased in shoots by 1,349% and 1,252%, respectively, as compared to control plants. Scanning-electron microscopic observations revealed that lead particles in both leaf and stem of EDTA and EDTA+IAA or NAA treated plants were concentrated at the region of vascular bundles. Lead particles were also found in the root tissue from the epidermis layer to the stele region. The results of this study should be helpful to increase the metals accumulating potential of plants.