These hyperaccumulation genes (HA genes) are found in over 450 plant species, including the model organisms "Arabidopsis" and the Brassicaceae. Expression of HA genes allows the plant to uptake and sequester metals such as As, Co, Fe, Cu, Cd, Pb, Hg, Se, Mn, Zn, Mo and Ni in 100–1000 times the concentration found in sister species or populations.