In general, uptake of a metal involves three phases: (i) metal
transport across the root cell plasma membrane, (ii) root to shoot
translocation, and (iii) metal detoxification and sequestration [30].
Of these, the most critical is the transport of metal across the plant
cell membrane. Plant cell walls have different chemical functional
groups that act as binding sites for metal uptake, mainly carboxyl,
amine and hydroxyl groups. Although considerable research has
been undertaken on elucidating the mechanism of uptake of essential
and non-essential metals, to date the mechanism for Au uptake