FENG Haiyan , ZHANG Lichuan , GAO Yuhang , LIU Zhiyi , HUANG Ka , LIAO Baoli , LAO Changling , HAN Zhixuan
2025, 45(3): 404-415.
The
extraction
and
beneficiation
of
rare
earth
elements(REEs)
have
led
to
severe
REEs
contamination
in
surrounding
soils,
water,
and
other
environmental
media.
Identifying
the
migration,
transformation,
speciation,
and
tolerance
mechanisms
of
REEs
in
soils
and
hyperaccumulators
can
provide
theoretical
basis
for
REE
contamination
remediation,
research
and
development
of
biomimetic
materials,
plant
mining,
and
other
fields.
This
review
summarizes
the
germplasm
resources,
REE
accumulation
characteristics,
and
physiological
mechanisms
of
REE
hyperaccumulators.
At
present,
25
REE
hyperaccumulators
or
potential
hyperaculmulator
species
have
been
identified
worldwide,
with
ferns
accounting
for
approximately
68%
of
these.
REEs
are
primarily
accumulated
in
leaves,
where
ferns
predominantly
enriching
light
rare
earth
elements ( LREEs),
while
species
from
the
genus
Phytolacca
exhibit
slight
enrichment
in
heavy
rare
earth
elements(HREEs).
The
mechanisms
underlying
the
fractionation
of
LREEs
and
HREEs
in
hyperaccumulators
involve
adsorption
and
precipitation
in
extracellular
cell
walls,
transmembrane
transport
within
the
symplast,
and
chelation
with
various
ligands.
The
physiological
mechanisms
of
REE
hyperaccumulators
can
be
divided
into
four
key
processes:(1)
Activation
of
REEs
in
the
rhizosphere
through
root
exudates,
phosphorus
deficiency,
and
microbial
interactions;
(2)
Efficient
root
uptake
of
REEs
via
both
apoplastic
and
symplastic
pathways,
potentially
involving
REE
transporters
and
other
ion
channels;
(3)
Xylem
transport,
where
REEs
form
chelates
with
organic
acids,
amino
acids,
and
other
ligands,
which
influences
the
translocation
of
LREEs
and
HREEs
to
aerial
parts;
(4)
Detoxification
and
storage
in
the
aboveground
parts,
where
REEs
are
bound
to
proteins,
polysaccharides,
and
organic
acids,
and
are
primarily
sequestered
in
inert
compartments
such
as
cell
walls
and
vacuoles.
