Root cortical aerenchyma improves the drought tolerance of m(7)
发布时间：2021-06-06
746J.Zhuetal.
consistentwiththeresponsetolowphosphorusavailability(Fanetal.2003;Zhu&Lynch2004).HigherRCAlineshavemorecorticalairspaceinroottissues(Figs1&7),whichmayreducerootcarboncostforrootmaintenanceinhigherRCAlines.Thus,higherRCAlinesmayhavemorecarbonandenergyavailableforrootconstruction,permittingexplorationofdeepersoilsunderwaterstress(Figs3,4,6,9&10).Covariateanalysisshowedthattherewasnosigni -cantrelationshipbetweentotalrootdryweightandper-centageofRCA(F=0.65,P=0.57).Inotherwords,RCAwasnotdrivenbythesizeofrootsystemorthesizeoftheplant(Fig.5).WefoundhighRCAlineswithdeeperrootingunderwaterstresshadhigherleafrelativewatercontent(Fig.11).Takentogether,these ndingsdemonstrateRCAplaysanimportantroleforplantadaptationtodrought.Wefoundthatseminalrootrespirationperunitlength(y1)wassigni cantlyassociatedwithpercentageofRCA
50Root length 40–50 cm deep
4030
2010080Root number 40–50 cm deep
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WSWW
a
ab
abc
cd
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de
WSWW
c–1
)Total root length (cm frame
60
bc
15
40
20
33
248
331
34
77
10
5
284364
Low RCAHigh RCA
Root counts (No. frame-1)
Recombinant inbred lines
Figure8.Rootlengthdensity(upperpanel)androotnumberdensity(lowerpanel)at56dafterplanting(DAP)from40to50cmdeepsoilcoresegmentsforsevengenotypesinbothwell-watered(WW)andwater-stressed(WS)conditionsinthe eld.Datashownaremeans SEofthemean(n=4).Meanswiththesamelettersarenotsigni cantlydifferent(P 0.05).
25201510
acquisition,sincedeepersoildomainsgenerallyhavegreaterwatercontentcomparedwithshallowsoildomains,asevidencedinthisstudybytimedomainre ectometry(TDR)measurementsinthe eld(Fig.6)andsoilwaterpotentialmeasurementsat35DAPinmesocosms.
Thereisincreasingevidencethatrootmetaboliccostsareanimportantcomponentofplantgrowthandadaptationunderlowphosphorusavailability(Zhu&Lynch2004;Lynch&Ho2005;Zhu,Kaeppler&Lynch2005c).Rootcostcanbeestimatedastotalbelow-groundexpenditureofcarbon,whichisusedforrootconstruction,rootmainte-nance,andionuptake(Lambers,Atkin&Scheurwater1996;Lambersetal.2002;Lynch&Ho2005).Inthisstudy,speci crootrespirationperunitoflengthandweightweresigni cantlyreducedbywaterstress(Fig.3),whichis
5
33
248
331
34
77
284
364
Low RCAHigh RCA
Recombinant inbred lines
Figure9.Rootlengthperframe(upperpanel)androotcounts
perframe(lowerpanel)byminirhizotrontechniqueat42dafterplanting(DAP)at50cmdeepsoilforsevengenotypesinbothwell-watered(WW)andwater-stressed(WS)conditionsinthe eld.Datashownaremeans SEofthemean(n=4).Meanswiththesamelettersarenotsigni cantlydifferent(P 0.05).
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