全 文 ：Differences of Uptake and Accumulation of Zinc in
Four Species of Sedum
LONG Xin_Xian , YANG Xiao_E , YE Zheng_Qian , NI Wu_Zhong , SHI Wei_Yong
(Institute of Agricultural Chemistry , College of Natural Resources and Environmental Sciences , Zhejiang University , Hangzhou 310029 , China)
Abstract:　Four species of Sedum L.were grown in nutrient solution for the comparison of their Zn uptake
and accumulation.S .alfredii Hance showed much greater tolerance to Zn than the other three species.Shoot
and root yields of S.sarmentosum Bunge , S.bulbiferum Makino , and S .emarginatum Migo decreased with
increasing Zn concentration in the solution , while shoot and root yields of S.alfredii increased when Zn con-
centration was ≤80 mg·L-1.At 80 mg·L-1Zn , Zn concentration in shoots of S .alfredii reached 19.09 mg
·g-1.S.alfredii was also more efficient in Zn translocation from roots to shoots , while Zn concentration in
shoots was much higher than in roots.However , this was not the case for the other three species.The results
showed that S .alfredii is a Zn hyperaccumulator and could be useful for the phytoremediation of Zn_contami-
nated soils.
Key words:　zinc;uptake;hyperaccumulation , Sedum alfredii
　　There exists genotypic difference in tolerance to
heavy metal toxicity in the environment.Some plants that
grow on naturally metal_rich or metal_contaminated soils
may adapt and develop to survive vividly and accumulate
much greater concentrations of heavy metal(s)in their
shoots than other plant species.The geochemical scien-
tist , Baker and Brooks[ 1] , firstly defined Ni hyperaccu-
mulator.Heavy metal hyperaccumulators are those plants
that have ability to uptake heavy metal(s)from soils ex-
traordinarily and transport and accumulate them in their
shoots.The concentration of heavy metal could be over
1 000 mg·kg-1(DW)for Cr , Co , Ni , Cu , Pb , and be
over 3 000-5 000 mg·kg-1(DW)for Zn[ 2] .For in-
stance , Thlaspi caerulescens is a well known Zn and Cd
hyperaccumulator identified in an ancient mining area in
Europe .Heavy metal(s)contaminated soils might become
clean after consecutive growth of such hyperaccumulator.
This is a novel technique to decontaminate heavy metal
polluted soils , and is named as phytoremediation[ 3-6 ] .
This new technique has many advantages over the tradi-
tional methods , such as physical or chemical remediation ,
and has shown its great potential in practice[ 6-9] .
The capacity of using hyperaccumulator to clean up
the heavy metal contaminated soils is determined by the a-
bility of plants to accumulate heavy metal(s)in their
shoots and yield of shoot biomass.However , most of the
naturally occurring hyperaccumulating plants grow ex-
tremely slowly , hence , phytoremediation has not achieved
widely in real cases now.Nevertheless , after a detailed
survey on the plant populations growing on some ancient
Pb_Zn mining areas in east China , we have found that
Sedum alfredii can tolerate and accumulate high Zn in its
shoots , and it might be a new Zn_hyperaccumulator origi-
nally found in China.This plant species has a large pro-
portion of above_ground part with a high growth potential.
Thus S.alfredii could be applied in remediation of Zn
contaminated soils.In the present paper , solution culture
experiment was conducted to compare growth response to
high Zn solution , Zn uptake , translocation from roots to
shoots and accumulation , among the four species of Se-
dum L.
1　Materials and Methods
1.1　Materials
Sedum alfredii Hance and Sedum sarmentosum
Bunge were collected from an old mining area in Southeast
China;Sedum bulbiferum Makino and Sedum emargina-
tum Migo were collected from Hangzhou City , Zhejiang
Province.Plants were grown in a glasshouse for the exper-
iment.
1.2　Plant culture
Plant roots were cleaned up with tap water and grown
in full nutrient solution.The composition of the nutrients
in solution was(in mmol·L-1):Ca(NO3)2·4H2O 2.0 ,
KH2PO4 0.10 , MgSO4·7H2O 0.50 , KCl 0.10 , K2SO4
0.70;and(in μmol·L-1):H3BO3 10.00 , MnSO4·H2O
0.50 , ZnSO4 ·7H2O 0.50 , CuSO4 ·5H2O 0.20 ,(NH4)6Mo7O24 0.01 , Fe_EDTA 100.S .alfredii and S.
sarmentosum were grown for 18 d , and S .bulbiferum
and S .emarginatum for 26 d for initiation of new roots.
Then they were exposed to different levels of Zn treat-
ments:CK , 5 , 10 , 20 , 40 , 80 , 160 , 240 , 320 mg·
L-1(Zn2+).Zinc was supplied as ZnSO4·7H2O and
each treatment had three replications.Solution was aerat-
ed 24 h and maintained at pH 5.8 adjusted daily with 0.1
mol·L-1 HCl or NaOH.Solution was renewed every four
days.Plants were harvested at the start and the end of Zn
treatment.At harvest , roots of intact plants were rinsed
Received:2001-01-13　Accepted:2001-05-20
Supported by the National Outstanding Young Science Foundation of China(39925024)
植　物　学　报　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

Acta Botanica Sinica　2002 , 44(2):152-157
with distilled water , then were immersed in 20 mmol/L
Na2_EDTA (disodium ethylenediaminetetraacetate)for 15
min to remove the Zn2+ adhered to root surfaces.Plant
samples were separated into shoots and roots , and the
base of stalks and root was rinsed thoroughly with deion-
ized water , blotted dry.Then the samples were first dried
at 105 ℃ for 30 min and finally dried at 70 ℃.Fresh
weight(FW)and dry weight (DW)of shoots or roots
were recorded.Samples of plant dry materials were
grounded with stainless steel grinder and passed 60 mesh
filter for Zn analysis.
1.3　Analysis of plant Zn
Plant samples of 0.100 g were dry ashed at 550 ℃
and dissolved in 1∶1(V∶V)HCl , then diluted to 50 mL
with deionized water , filtered.Zinc concentration of the
solution was determined by inductively coupled plasma
spectroscopy (ICP_OES).
2　Results
2.1　Zinc toxicity symptoms
Typical symptoms of Zn toxicity of S .sarmentosum ,
S .bulbiferum and S .emarginatum were that plant
leaves wilted , growth of plant was inhibited , root tips
were necrotic and browned at Zn toxicity levels(Fig.1).
Toxicity symptoms became more serious with the increas-
ing of Zn level.Symptoms were observed on roots of S.
bulbiferum and S .emarginatum grown for 4 d when Zn
level was ≥80 mg·L-1;some plants of S .bulbiferum
were dead at 8 d with 320 mg·L-1 Zn.While plants of
S .sarmentosum appeared to be wilted at 2 d with Zn ≥
160 mg·L-1 , some plants were dead at 10 d with Zn ≥
160 mg·L-1.However , plants of Sedum alfredii grew
healthy and did not show any symptom of Zn toxicity dur-
ing the period of the experiment(Fig.1).
2.2 　Biomass production of four species of Sedum
affected by Zn
Growth of the four plant species responded to Zn dif-
ferently (Fig.2).Root growth (dry weight)of S.bulb-
iferum decreased with increasing Zn in solution.Dry
weight of root was not significantly affected until 80 mg·
L-1 Zn in solution , but no significant difference was
found among the treatment in the range of 80-320 mg·
L-1 Zn.Root growth of S.emarginatum was strikingly
reduced by Zn treatment till 80 mg·L-1.Further increase
of Zn concentration in solution , however , did not affect
root growth greatly.However , root growth of S.sarmen-
tosum had little response to Zn.By contrast , root growth
of S .alfredii increased with increasing Zn in solution ,
and reached maximum at 80 mg·L-1 Zn.
Fig.1.　Growth responses of four species of Sedum to Zn.
LONG Xin_Xian et al:Differences of Uptake and Accumulation of Zinc in Four Species of Sedum linn 153　
Fig.2.　Shoot and root biomass of four species of Sedum.
SDM , shoot dry matter;RDM , root dry matter.
　　 Shoot growth was more sensitively affected by Zn
than root growth (Fig.2).At the range of Zn below 80
mg·L-1 , shoot dry weights of S.sarmentosum , S .
bulbiferum and S .emarginatum were greatly decreased
by Zn supply.At 80 mg·L-1 Zn level , shoot dry weights
of S.sarmentosum , S .bulbiferum and S.emarginatum
were only 62%, 47% and 33%of the control respective-
ly .In contrast , shoot growth of S.alfredii increased with
Zn supply and the maximum shoot dry weight reached at
80 mg·L-1Zn , which was 36%heavier than the control.
However , shoot dry weight decreased with further increas-
ing Zn in solution.Shoot dry weight at 320 mg·L-1 Zn
was 27% less than that at 80 mg·L-1 Zn.
2.3　Zinc uptake and distribution
Great difference existed among the four species , not
only in plant growth , but also in Zn uptake and its distri-
bution.
2.3.1 　Zn concentration 　Concentration of Zn in
shoots of S.alfredii was extraordinarily higher than the
other three species at any Zn level(Table 1).The maxi-
mum Zn concentration in shoot of S.alfredii reached
19.09 mg·g-1 Zn at 80 mg·L-1 Zn.In contrast , there
were no significant differences of Zn concentration in
shoots of the other three species.Shoot Zn concentration
in S .sarmentosum increased with Zn supply , while shoot
Zn in S .emarginatum and S.bulbiferum reached maxi-
mum at 20 or 240 mg·L-1 Zn , respectively.Higher Zn
concentration in solution resulted in decrease of Zn con-
centration in the shoots.
Root Zn concentration increased with Zn level , but
much less than shoot Zn for S .alfredii , and vice versa
for the other three species.
Ratio of Zn concentration of shoots to roots(S/R)in
S .alfredii was >1 at any Zn level , ranged at 29.4-
1.4 , with means of 7.8±9.3.But S/R decreased with
the increase of Zn concentration in solution.By contrast ,
S/R was always <1 for the other three species(except
S .sarmentosum at the control).The results implied that
S .alfredii is a new Zn hyperaccumulator.
2.3.3　Accumulation and distribution of Zn　Uptake
of Zn by S .bulbiferum increased with Zn supply , and
leveled off at 240 mg·L-1 Zn(Fig.3).The maximum Zn
accumulation in the shoot was (178.27±28.79)μg·
plant-1 , while Zn accumulation in shoots of S .sarmen-
tosum reached its maximum ((128.10±19.25)μg·
plant-1)at 320 mg·L-1 Zn.However , Zn accumulation
in S.emarginatum increased with Zn supply firstly ,
peaked at 20 mg·L-1 Zn ((274.20 ±45.55)μg ·
plant-1), then decreased greatly when Zn supply was in-
creased further , while Zn accumulation in S .sarmento-
sum increased with Zn supply , and reached its maximum
at 320mg·L-1Zn((128.10±19.25)μg·plant-1).By
contrast , Zn accumulation in shoots of S.alfredii was re-
markably greater than that of the other three species.The
maximum Zn accumulation in shoots was (12 994 ±
1 081)μg·plant-1 at 80 mg·L-1 Zn.Due to decrease of
shoot biomass and Zn concentration , Zn accumulation in
shoot decreased with solution of Zn>160mg·L-1.Simi-
larly , accumulation of Zn in root increased with Zn sup-
ply , but decreased at certain higher Zn levels due to
smaller root dry matter yield.
Distribution of Zn in shoots decreased with
154　 植物学报　Acta Botanica Sinica　Vol.44　No.2　2002
Table 1　Concentration of Zn(mg·g-1 DW)in the shoots and roots of the four species of Sedum
Treatment
(mg·L-1)
S.alfredii S.bulbiferum S.emarginatum S.sarmentosum
Shoot Root S/R Shoot Root S/R Shoot Root S/R Shoot Root S/R
CK 6.421 0.219 29.38 0.077 0.189 0.41 0.188 0.208 0.90 0.156 0.131 1.19
5 9.174 0.581 15.79 0.294 1.061 0.28 0.499 0.847 0.59 0.240 1.221 0.20
10 10.43 1.265 8.25 0.481 1.652 0.29 0.522 1.425 0.37 0.241 1.093 0.22
20 13.44 3.033 4.43 0.642 2.747 0.23 1.320 2.322 0.57 0.256 1.665 0.15
40 17.06 3.256 5.24 0.716 3.770 0.19 0.717 3.386 0.21 0.326 1.978 0.16
80 19.09 7.918 2.41 0.904 7.559 0.12 0.637 7.418 0.09 0.364 2.623 0.14
160 16.88 9.712 1.74 0.920 10.43 0.09 0.406 11.42 0.04 1.290 7.279 0.18
240 17.03 11.97 1.42 1.601 11.52 0.14 0.636 22.12 0.03 1.298 8.113 0.16
320 17.91 12.49 1.43 1.313 11.73 0.11 0.864 22.59 0.04 2.325 8.232 0.28
LSD(P<0.05) 2.646 0.939 0.223 2.348 0.119 2.331 0.226 0.907
LSD(P<0.01) 3.626 1.287 0.306 3.217 0.163 3.195 0.310 1.244
＊S/R= shoot Zn concentration/root Zn concent ration
Fig.3.　Accumulation of Zn in shoots and roots of four species of Sedum.
increasing Zn in solution.However , remarkable greater
partition of Zn was in the shoots of S .alfredii than the
other three species.Regardless of plant species , most of
the Zn accumulated was in the shoot when solution Zn was
low , especially in the control.Percentages of Zn in shoots
over the whole plants ranged 92.9%-63.0%, 91.3%-34.3%, 31.8%-83.7%and 99.8%-94.4%, on
average of(77.2±13.2)%, (69.2±23.4)%, (41.93±17.63)% and (97.3±2.6)% for S .bulbiferum ,
S .emarginatum , S.sarmentosum and S.alfredii , re-
spectively (Fig.3).
2.4　Translocation of Zn from roots to shoots
Zinc transport(TR)rates from roots to shoots were
calculated according to the following equation[ 10] :TR =[(SU2-SU 1)/(t 2-t1)] ×[(LnSW2-LnSW1)/(SW2-SW1)] .
Where SU =Zn concentration in shoots (mmol·
plant
-1), SW=shoot dry weight(g·plant-1), t=time(days)of sampling at the start (subscript 1)and end(subscript 2)of Zn treatment , TR =Zn transport (TR)
rates , and was converted to nmol·g-1 SW·s-1.
Transport of Zn from roots to shoots differed greatly
among the four species (Fig.4).As for S .bulbiferum
and S.emarginatum , TR of Zn increased with Zn sup-
ply , and there were no significant differences between the
two species.While for S .sarmentosum , the TR of Zn
increased slightly from CK to 80 mg·L-1Zn , but at high-
er Zn supply (≥160 mg·L-1), the TR of Zn increased
sharply.The change of TR of Zn in S.alfredii showed
the same pattern as Zn concentration and accumulation in
shoots , and the TR of Zn reached maximum at 40 mg·
L
-1
Zn.When solution Zn concentration ≤40 mg·L-1 ,
the TR of Zn decreased in the order of S .alfredii >
S .sarmentosum >S .bulbiferum and S .emarginatum.
LONG Xin_Xian et al:Differences of Uptake and Accumulation of Zinc in Four Species of Sedum linn 155　
Fig.4.　Zinc transport(TR)from roots to shoots of four species of Sedum.
But at ≥160 mg·L-1 Zn , the TR of Zn in S.sarmento-
sum was higher than that in S .alfredii.This may be due
to the low dry matter yield of Sedum sarmentosum .
3　Discussion
Among the four species , the results showed that S .
alfredii had the greatest capability of Zn uptake , transport
and tolerance to high Zn.At 80 mg·L-1 Zn , apparent
symptoms of Zn toxicity appeared in S .sarmentosum , S .
bulbiferum and S .emarginatum , while not in S.al-
fredii , though shoot growth of S .alfredii also slowed
down at Zn higher than 80 mg·L-1 Zn.The critical con-
centration for Zn toxicity is around 100 -300 mg ·
kg
-1[ 11] .The maximum shoot Zn concentration was as
high as 19.09 mg·g-1 DW for S.alfredii (Table 1),
whereas , less than 2.5 mg·g-1 DW for the other three
species.Furthermore , shoot growth of S.alfredii in-
creased with Zn supply up to 40 mg·L-1 , whereas the
other three species did not.The results indicated that Zn
requirement for normal growth of S .alfredii was much
greater than most plant species , and potential of tolerance
to high Zn was also remarkably stronger.These character-
istics of S .alfredii were similar to that of Thlaspi
caerulescens , a well known Zn hyperaccumulator [ 12 , 13].
Plants that adapt to high Zn stress are classified into
two types according to their survival mechanism[ 14] :(a)
Excluder—uptake and transport of Zn into shoot and con-
centration of Zn in shoot maintain at certain low level thus
avoiding Zn toxicity when Zn in the medium is relatively
low.However , plants are then suffering from Zn toxicity
when Zn reached the critical level.(b)Accumulator —
this type of plants is able to take up Zn and accumulate
Zn in their shoots from the environment where Zn in the
medium ranges in a very large scale.The response of
plant to high Zn is different from others.These plants
have been suggested to be “hyperaccumulator” instead of
“accumulator”[ 15] .Both S.alfredii and S .sarmento-
sum grow in Pb_Zn mining area , and are two superior
plants as well.However , Zn uptake and partitioning be-
tween shoots and roots differed one from another.Ratio of
Zn concentration of shoots to roots(S/R)was always less
than 1 for S.sarmentosum.In contrast , S/R >1 ,
ranged from 19.4-1.4 for S.alfredii.The critical lev-
els for Zn hyperaccumulator have been reported to be
3 000 mg·kg-1[ 16] .The results suggested that S.al-
fredii is a Zn hyperaccumulator.More interesting is that
there existed different mechanisms between S.alfredii
and S.sarmentosum in their response to high Zn (Fig.
4).But further work is needed.To our knowledge , S.
alfredii is a newly found hyperaccumulator for Zn in Chi-
na.
Moreover , according to survey in the field , shoot dry
matter of S .alfredii was as high as 1 800 kg/hm2.
Thus , in comparison to T.caerulescens , S .alfredi has
its characteristics of fast growth , large biomass , asexual
reproduction and being perennial.Hence , there is a great
potential for S.alfredi to be used for remediation of Zn
contaminated soils.
References:
[ 1] 　Baker A J M , Brooks R R.Terrestrial higher plants which
hyperaccumulate metallic elements.Biorecovery , 1989 , 1:
81-97.
[ 2] 　Reeves R D , Baker A J M.Metal_accumulating plants.
Raskin H , Ensley B D.Phytoremediation of Toxic Metals:
Using Plants to Clear up the Environment.New York:John
Wiley &Sons.Inc., 2000.231-246.[ 3] 　Nedelkoska T V , Doran P M.Characteristics of heavy metal
uptake by plant species with potential for phytoremediation
and phytomining.Minerals Engineering , 2000 , 13:549 -
561.[ 4] 　Raskin I , Smith R D , Salt D E.Phytoremediation of met-
als:using plants to remove pollutants from the environment.
Curr Opin Biotech , 1997 , 8:221-226.[ 5] 　Ebbs S D, Lasat M M , Brady D J , Cornish J , Gordon R,
Kochian L V.Phytoextraction of cadmium and zinc from a
contaminated site.J Environ Qual , 1997 , 26:1424 -
1430.
[ 6 ] 　Salt D E , Smith R D , Raskin I.Phytoremediation.Annu
Rev Plant Physiol Plant Mol Biol , 1998 , 49:643-668.[ 7] 　Watanabe M E.Phytoremediation on the brink of commer-
cialization.Environ Sci Technol , 1997 , 31:182A-186A.[ 8] 　Ebbs S D , Kochian L V.Toxicity of zinc to Brassica
species:implication for phytoremediation.J Environ Qual ,
1997 , 26:776-781.[ 9 ] 　Ebbs S D , Kochian L V.Phytoextraction of zinc by oat
(Avena sativa), barley (Hordeum vulgare), and Indian
mustard(Brassica juncea).Environ Sci Technol , 1998 ,
32:802-806.
[ 10] 　Yang X , Baligar V C , Martens D C , Clark R B.Cadmium
effects on influx and transport of mineral nutrients in plant
species.J Plant Nutr , 1996 , 19:643-656.[ 11] 　Marschner H.Mineral nutrition of higher plants.2nd ed.
San Diego:Academic Press , 1995.
156　 植物学报　Acta Botanica Sinica　Vol.44　No.2　2002
[ 12] 　Brown S L , Chaney R L, Angle J S , Baker A J M.Zinc
and cadmium uptake by hyperaccumulator Thlaspi
caerulescens grown in nutrient solution.Soil Sci Soc Amer J ,
1995 , 59:125-133.[ 13] 　Shen Z G , Zhao F J , McGrath S P.Uptake and transport of
zinc in the hyperaccumulator Thlaspi caerulescens and the
non_hyperaccumulator Thlaspi ochroleucum .Plant Cell Env-
iron , 1997 , 20:898-906.[ 14] 　Baker A J M.Accumulators and excluders_strategies in the
response of plants to heavy metals.J Plant Nutr , 1981 , 3:
643-654.[ 15] 　Dahmani_Muller H , van Oort F , Gelie B , Balabane M.
Strategies of heavy metal uptake by three plant species grow-
ing near a metal smelter.Environ Poll , 2000 , 109:231-
238.[ 16] 　Salt D E , Kramer U.Mechanisms of metal hyperaccumula-
tion in plants.Raskin H , Ensley B D.Phytoremediation of
Toxic Metals:Using Plants to Clear up the Environment.
New York:John Wiley &Sons.Inc., 2000.231-246.
四种景天属植物对锌吸收和累积差异的研究
龙新宪　杨肖娥　叶正钱　倪吾钟　石伟勇
(浙江大学环境与资源科学学院农业化学研究所 , 杭州 310029)
摘要:　采用营养液培养试验 , 比较研究了 4 种景天属植物对 Zn 的吸收 、积累和运输特性。结果表明 , 东南景天
(Sedum alfredii Hance)耐 Zn 毒的能力远强于珠芽景天(S.sarmentosum Bunge)、凹叶景天(S.bulbiferum Makino)和垂
盆草(S .emarginatum Migo), 其地上部和根系的干物质产量随着 Zn浓度的增加而逐渐减少;当浓度≤40 mg·L-1时 ,
东南景天的地上部和根系的干物质产量均随 Zn浓度的增加而增加 ,其地上部 Zn含量 、积累量及其 Zn 运输速率均
显著高于珠芽景天 、凹叶景天和垂盆草;当 Zn 浓度低于 80 mg·L-1时 ,东南景天地上部 Zn 含量随着营养液中 Zn 浓
度的增加而增加 ,在 80 mg·L-1浓度 ,其地上部 Zn含量高达 19.09 mg·g-1。东南景天的地上部 Zn含量/根系 Zn 含
量的比值大于 1 ,而株芽景天 、凹叶景天和垂盆草的地上部 Zn 含量/根系 Zn含量比值小于 1。东南景天是在我国首
次发现的具有生物量大 、生长速率快的一种新的 Zn 超积累植物。
关键词:　锌;耐性;超积累
中图分类号:Q945.12　　　文献标识码:A　　　文章编号:0577-7496(2002)02-0152-06
收稿日期:2001-01-13　接收日期:2001-05-20
基金项目:国家杰出青年科学基金(39925024)。
(责任编辑:梁　燕)
Erratum
　　On page 368 , 43(4)of Acta Botanica Sinica , Li et al., Study on the Flexistyly PollinationMechanism in Alpinia
Plants(Zingiberaceae), in Table 2 , column “Phenotypes” , the “Cataflexistyle” should be “Hyperflexistyle” , and the“Hyperflexistyle” should be “Cataflexistyle” (and not vice versa , as published).
LONG Xin_Xian et al:Differences of Uptake and Accumulation of Zinc in Four Species of Sedum linn 157