Transgenic poplar for phytoremediation

Abstract

Heavy metals such as cadmium (Cd) and lead (Pb) are released into the environment by mining, industry, and agriculture. Phytoremediation is a low-cost and environmentally-friendly technology to clean up polluted sites. For effective phytoremediation, plants that can tolerate high level of pollutants are necessary. To engineer plants with enhanced metal tolerance and accumulation properties, we searched for genes that can improve heavy metal resistance through yeast mutant screening and Arabidopsis cDNA library screening, and found ScYcf1, ScYHL035C, ScPdr13, and AtPcr1. ScYcf1 and ScYHL035C are multidrug resistance-associated protein (MRP) subfamily of ABC transporter. ScPdr1 is a heat shock protein 70(HSP70). AtPcr1 is a plant protein which enhances cadmium resistance by reducing Cd(II) in the cell. We expressed the genes in poplar, a species that grows fast to high biomass, important characters of plants for application of phytoremediation. To prevent pollen dissemination from the transgenic plants, we introduced the genes into non-flowering mutant poplar. We compared growth of the transgenic and wild type poplar plants in Cd- and Pb-containing media, and found that the transgenic poplars were highly improved in the heavy metal resistance. These results suggest that they are useful for phytoremediation of Cd- and Pb-contaminated soils.