Cadmium-induced alterations in m

ActaPhysiolPlant(2013)35:2105–2112DOI10.1007/s11738-013-1247-4

ORIGINALPAPER

Cadmium-inducedalterationsinmorpho-physiologyoftwopeanutcultivarsdifferingincadmiumaccumulation

ZhengZhang CaifengLiu XumingWangGangrongShi

Received:28October2012/Revised:31January2013/Accepted:21February2013/Publishedonline:5March2013

´rskiInstituteofPlantPhysiology,PolishAcademyofSciences,Krako´w2013ÓFranciszekGo

AbstractThisstudyexaminesdifferencesinthemorpho-physiologicalresponsesoflow-andhigh-cadmium(Cd)

accumulatingpeanut(ArachishypogaeaL.)cultivarstoCdstress.Thebiomass,Cdaccumulation,leafgasexchange,rootmorphology,rootrespiration,andhydraulicconduc-tivityofQishan208(low-Cdaccumulator)andHaihua1(high-Cdaccumulator)weredeterminedviaahydroponicexperiment.Exposureofpeanutplantsto2and20lMCdconsiderablydecreasedtheirshootbiomass,netphotosyn-theticrate,transpirationrate,stomatalconductance,totalrootlength,numberofroottips,rootrespiration,andhydraulicconductivity.Therootbiomass,rootsurfacearea,andaveragediameterwereunaffectedbyCdexposure.ThetwocultivarsdifferedinCdaccumulationandmorpho-physiologicalresponsestoCdstress.Qishan208accumu-latedlessCdinplanttissuesbutwasmoresensitivetoCdstressthanHaihua1.Thetotalrootlength,surfacearea,averagediameter,numberofroottips,androotrespirationrateofHaihua1weresigni cantlyhigherthanthoseofQishan208.Thewell-developedrootsystemandhigherrootrespirationofHaihua1mayberesponsibleforitshighCdaccumulationcapacity.

KeywordsPeanutÁCultivarvariationÁCadmiumaccumulationÁRootmorphologyÁRootrespiration

Introduction

Cadmium(Cd)isanon-essentialmetalthatishighlytoxictomostorganisms.Cdiseasilytakenupbyplantrootsandcanbeloadedintothexylemfortransportintotheaerialpartsofaplantbecauseofitshighsoil–plantmobility.ThetransferofCdtothefoodchainposesseriousthreatstohumanhealthandhasbecomeamajorpublicconcern(Limaetal.2006).Thus,understandingthemechanismsinvolvedinCdaccumulationisnecessarytoreduceCdconcentrationsintheediblepartsofcrops.

Cdistakenupbytherootthroughtheepidermisandtraversestherootcortexviasymplasticandapoplasticpathwaysbeforeenteringthexylemandtranslocatingtotheshoot.GiventhattheapoplasticpathwayisblockedbytheCasparianband,thexylemloadingofCdinrootsoccursthroughanenergy-dependentsymplasticpathway,inwhichanumberofmembranetransportersofessentialnutrients,suchasiron(Fe),zinc(Zn),andcalcium(Ca),areinvolved(Clemens2001).Therefore,rootrespirationmaybeinvolvedintheuptakeofCdinplants.

Therootisthe rsttargetofCdphytotoxicity,andtheinteractionsbetweenCdandrootcellscanleadtophysi-ologicalalterationsinvolvedintheuptakeandtransportofmineralnutrients,suchasmembranedamageandchangesinenzymeactivities(Astol etal.2003,2012,2005;Nocitoetal.2006;Rizzardoetal.2012).WhileCdiswidelyknowntoinhibitrootelongationandbiomassaccumulation(Groppaetal.2008;Limaetal.2006;Lux

´guez-Serranoetal.2006),littleinfor-etal.2011;Rodr

mationisavailableaboutthemorpho-physiologicalresponsesofplantrootstoCdtoxicity.

Rootmorphologyin uencestheaccumulationofmin-eralelements.Dongetal.(1995)reportedthattheZn-ef cientgenotypeofwheathaslongerandthinnerroots

CommunicatedbyS.Renault.

Z.ZhangÁC.LiuÁX.WangÁG.Shi(&)

CollegeofLifeSciences,HuaibeiNormalUniversity,Huaibei235000,People’sRepublicofChinae-mail:swsgr@http://doc.xuehai.net

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