全 文 ：　第 47卷　第 4期
2008年　7月
中山大学学报 (自然科学版)
ACTA　SCIENTIARUM　NATURALIUM　UNIVERSITATIS　SUNYATSENI
Vol.47　No.4
Jul.　2007 　
ComparativeStudiesonStructuralFeatureofVesselsofFourGeneraofCycadswithAngiosperm＊
HUANGYu-yuan1, 2 , LIAOWen-bo3 , ZHANGHong-da(ChangHung-ta)3 , WANGJia-zhuo2 , WUYing-hui4
(1.ColegeofLifeSciences, ZhongkaiUniversityofAgricultureandEngineering, Guangzhou510225, China;
2.AgriculturalColege, GuangxiUniversity, Nanning530005 , China;
3.SchoolofLifeSciences, SunYat-senUniversity, Guangzhou510275, China;
4.HaikouInstituteofAgriculturalScience, Haikou570311, China)
Abstract:ThetissuesofleafofCycastaiwaniana, BoweniaserrulataandDiooneduleandtissueofrootofMacrozamialongispinaof
cycads, andleavesofMicheliaalbaandAmygdaluspersicaofangiospermwereobservedbyscanningelectronmicroscope.Theresults
showedthattherearemanytypesofvesselsinfourgeneraoftwofamiliesofcycads, themannerandprocessofdevelopmentandconsti-
tutioninstructuralcharacteristicsofvesselofcycadsandangiospermareidentical, somecharactersofvesselsuchasinclinedextentof
perforationplateofendwaletc.showedthatsomeangiospermaremoreprimitivethenthatofcycads.Invesselsofspeciesofangio-
sperm, manyarebandshape, andwithoutendwall, onlyhavetwolateralwallsandanothertwonarrowmargins, thetopisacuteor
withanarcmargin, manyperforationslocatedinlateralwall.Cognizedtovesselofcycads, helpustounderstandthemechanismwhich
thesemostprimitiveseedplantsextanthowtoadaptedtoharshenvironmentsandtheirevolutionarylevel, andhassignificancetouse
efficiencymeasureprotecttheserarityplantsandhassignificancetoplantanatomy, plantsystematicsandplantevolution.
Keywords:Cycads;vessel;angiosperm;evolution;structuralcharacteristic;adaptability
CLCnumber:Q941;Q944.6　　Documentcode:A　　ArticleID:0529-6579 (2008) 04-0077-11
　　Cycadsareveryprimitiveseedplantsofpresent
existence, theystilpossessprimitivecharacteristicsin
externalmorphologyandinternalstructure, suchas
spermwithflagelum.Theyareclassifiedintothree
families:Cycadaceae, StangeriaceaeandZamiaceae.
Inthepast, itwasbelievedthatthewater-transporting
elementsincycadvasculartissuewouldbeonlyprimi-
tivetracheids[ 1 -6] .HuangandZhang[ 7] publisheda
briefreportthatfirstdiscoveredvesselinZamiafurfu-
raceaofcycads, Lin＆.Huang[ 8] publishedanother
briefreportonvesselfeatureinrootofCycaselonga,
HuangandWu[ 9] discoveredvesselinCycaspanzhi-
huaensis.
Furtherresearchintothestructuralcharacteristics
oftheirtissuesisimportantfortakingefectivemeasures
tocultivate, breedandcreatetherightcircumstancesto
enlargethepopulationandthenaturalcommunity.The
presentstudymakesacomparativeresearchoncycads
offourgenerawithangiosperminthestructurefeature
ofthexylemofthevasculartissueisanatempttoad-
dressthisdeficit.
1　Materialsandmethods
ThepinnasofleafofCycastaiwanianaCarruth.of
Cycadaceae, DiooneduleLindl.ofDioongenus, root
ofMacrozamialongispinaP.I.Forst.＆D.L.Jonesof
ZamiaceaewerecolectedfromlivingcycadsintheCy-
cadGardenofShenzhenFairyLakeBotanicalGarden,
Shenzhen, China.ThepinnaofleafBoweniaserrulata
(W.Bul)Chamb.ofZamiaceaeiscolectedfrom
SouthChinaBotanicalGarden, Guangzhou, China,
leavesofMicheliaalbaDC.Syst.andAmygdalusper-
sicaLinn.werecolectedfromthecampusofGuangxi
University, Nanning, China.Thevoucherspecimens:
Cycastaiwanianapinna:Y.Y.Huang＆ Y.H.Wu
376, Boweniaserulatapinna:Y.Y.Huang＆ L.J.
Wei361;Dioonedulepinna:Y.Y.Huang＆ A.H.
Huang384, Macrozamialongispinaroot:Y.Y.Huang
＆ Y.H.Wu388, Micheliaalbaleaf:J.Z.Wang＆
Y.Y.Huang020, Amygdaluspersicaleaf:J.Z.Wang
＆Y.Y.Huang019 , aredepositedattheHerbariumof
theAgriculturalColegeofGuangxiUniversity(GX-
AC).Aftercolection, thesematerialswerecutinto1
＊ 收稿日期:2007-09-25
基金项目:国家自然科学基金资助项目 (30260007, 30410203270)
作者简介:黄玉源 (1959年生), 男 , 教授 , 博士;E-mail:lqxhyy@yahoo.com.cn
中山大学学报 (自然科学版) 第 47卷　
cm×1 cminsize, andfixedimmediatelyinFAA(for-
malin40%∶aceticacidinglacial∶ethanol70%, 5∶5∶
90 invol.)maceratedanddissociatedbyJefrey s
technique[ 10.11), andrinsedwithwater.Thedissocia-
tedmaterialsweredehydratedinagradedseriesofeth-
anol/ isoamylacetateandcriticalpoint-driedinCO2 ,
thensputer-coatedwithgoldforobservationandpho-
tographyusingXL-30 ESEMandJEM-1200Ex/s
scanningelectronmicroscope(SEM).
2　Results
Examinationofdissociatedmaterialsoftheleaf
androottissuesoffourcycadgeneraandtwogeneraof
angiospermshowedthattherearemanyvesselelements
intheconductingtissueofthexylem.Thestructural
characteristicsofvesselsinthefourcycadplantsand
twoplantsofangiospermsaredescribedbelow.
CycastaiwanianaThereareannular, spiral,
scalariformvessel(Figure1A, B), pitedvesseland
reticularvessels(Figure1C, D)inthepinnaofleaf.
Theshapesofthesevesselsarenearlysquare, polygo-
nal, nearlycircularetc.Therearebothsimpleand
multipleperforationplatesintheendwal.Theend
walsofannularvesselaregeneralsimpleperforation
plateandpossessnearlyhorizontalorhorizontalperfora-
tionplate, alargeperforationlocateinperforationplate
ofendwal(Figure1A).Therearemoreofthemulti-
pleperforationplates, withthreetotenperforationsin
eachplate(Figure1B＆D), andtheirendwalperfo-
rationplatearemainlyinclination.Someendwalper-
forationplatehavealitletail, andwithatwisting
shape.
Fig.1　SEMphotographsofvesselelementsofleafofCycastaiwaniana
A:Aspiralvesselelementwhichpossessalargeperforationinhorizontalperforationplate.(EP:Endwalperforationplate, PC:
Parenchymacel).B:Asalariformvesselelementwithascaraliformperforationplateinendwallandsomelateralwalperforations.
(LP:Lateralwalperfration).C:Pittedvesselelement, whichpossessanearhorizontalendwalperforationplatewithseveralpefo-
rations.D:Areticularvesselelement, ithasainclinedmutipleperforationplateinendwall, andwithalittletail
Theportionoflateralwalsneartheendwalscon-
sistofonlyprimarywalswithoutsecondarythickening
formedalsoperforations.Insomelargerperforations,
theornamentationandperforationscanbeseenlocated
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intheinteriorwalofthevessels(Figure1B).Ana-
lyzedtotheseperforationsshowed:theirdiameteror
lengthareverylarge, suchasinsimpleperforation
plateofendwalofannularvessel, thediameterofa
circularperforationhaveapproached8μm, thelengdth
ofperforationslocatedinmultipleperforationplates
havereached10 ～ 12 μm, theirwidthcanreach4 ～ 5
μm;comparewithmanyangiospermswhichtheirdi-
ameterofperforationofvesselhaveonly2μm[ 12] ;or
lengthisonly6 ～ 8μm, widthonlyis3 ～ 5 μm[ 13] ,
iluminatedthatcycadsvesselpossesslargerperfora-
tions.
Thediameterofannularandspiralvesselsis
10.03 ～ 12.69 μm, Thediameterofscalariformvessel
is19.22 ～ 25.32 μm, Thediameterofpitedvesselis
19.81 ～ 32.06 μm.Thecelwalofparenchymacels
onlyconsistofprimarywalarenotdissolvedbyen-
zymes[ 14] , thereforetheypreservetheirintegrityofthin
membranewal, theyarewithoutperforationsintheir
celwal(Figure1A), perforationscanbeseenonly
intrachea.
BoweniaserrulataInthepinnamaterial, scalar-
iformvessel, pitedvesselandreticularvesselwere
seen(Figure2A– D), manyperforationsinendwal
andlateralwal.Somelateralwalperforationswereso
large, thatornamentationandperforationsintheinteri-
orwalswereseenveryclear(Figure2B, D).These
vesselspossesslongerandwideperforation, thetrans-
verseseptasorbarsconsistofsecondarywalaremore
longer, reach14 ～ 17μm.Insomevessels, manyper-
forationslocateinoneortwosidesoflateralwal, but
othersectionofwalshavenotperforation(Figure
2C), somevesselshavealreadyformedperforationin
severalsidesoflateralwal(Figure2D).Thephe-
nomenonwasseenthatscalariform perforationina
side, pitedperforationinanothersideoflateralwal
(Figure2B).
Thediameterofscalariform vesselis18.30 ～
23.28 μm, thediameterofpitedvesselis17.64 ～
28.16 μm.thediameterofreticularvesselis25.41 ～
Fig.2　SEMphotographsofvesselelementsofpinnaofBoweniaserrulata
A:Areticularvesselelementwhichhaveahorizontalendwalwithalittletail, theremoreperforationslocateinlateralwal.B:
Showingscalariformvesselelement, somelongperforationslocateinendwal.(P:Perforation).C:Apitedvesselelementwhich
possesssomepittedperforationsinlateralwall.(LP:Lateralwalperfration).D:Ascalariformvesselelement, thereissomescalari-
formperforationsinlateralwal(OPIW:Ornamentationsandperforationsintheinteriorwals)
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中山大学学报 (自然科学版) 第 47卷　
39.22 μm.Someendwalareinclinedperforation
plates(Figure3A＆ F), thedegreeofinclinationis
smalinmanyvessels(Figure3F).Someendwalof
vesselsarenearhorizontalorhorizontal(Figure2A;
Figure3C).Manyofvesselsarerectangleorpolygo-
nal.Inendwalandlateralwal, someprimarywal
Fig.3　SEMphotographsofvesselelementsofpinnaofBoweniaserrulata
A:Ascalariformandareticularvesselelement, showingtheinclinedperforationplate.(RV:reticularvesselelement).B:Two
pitedvesselelements, toshowtheinclinationperforationplateofendwal, thereareseveralperforationsintheplate, andsome
threadlikeremnantsofprimarywalintheperipheryofperforations.C:Severalscalariform-pittedvesselelements, toshowtheirhorizontalendwall.(EP:Endwalperforationplate).D:Apittedvesselelement, ithassomepitedperforationsinlateralwal,
thereissomethreadlikeormesh-likeremnantsofprimarywalintheperipheryofperforations.(PM:Primarywallmembrane;
LP:Lateralwallperforation).E:Apitedvesselelement, somesiteshaveformedperforationsandsomepitspreservestilentire
primarywallasalayermembraneinperipheryofornamentationwhichconsistofsecondarywal.F:Severalpittedvesselelements,
toshowtheirinclinedendwallperforationplates, therearesixtosevenperforationsintheplate
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　第 4期 黄玉源等:苏铁类植物 4个属的导管与被子植物导管结构特征的比较研究
whichwrapinoutsideofvesselhavenotbeendissolved
completelybyenzymes, thereforepreservetheirsome
threadlikeormesh-likeremnantsofprimarywalinthe
peripheryofperforations(Figure3B, D, F)[ 13, 15] .
Buttherehaveformedsomesmalperforationswhich
onlyoverahalfinentiresize, thentheseremnants
completedisappearing, theywilformlargeandentire
perforations.Thelengthinmanyperforationswhichlo-
catedendwalorlateralwalofscalariformvesseland
reticularvesselhavealreadyreach15 μmsomeap-
proach20μm, somereticularveselareover20 μm
(Fig.3A), andwidthare5 ～ 7 μm.
Insomevesselelements, aportionofveselwal
haveformedperforation, orremainfewmembranerem-
nantsintheoutsideofperforation, andothersitespre-
servestilentireprimarywalasalayermembranein
peripheryofornamentationwhichconsistofsecondary
wal(Figure3E).
DiooneduleInpinna, annular, spiralandpited
vesselswereseen.Insomespiralvessels, moreperfo-
rationshaveformedinlateralwal, somesitesstilpre-
servethemembraneremnantsintheperipheryofperfo-
rations, butsomespiralorannularvesselspreservestil
amoreentireprimarywalintheperipheryofvesselel-
ements(Figure4A).Theirendwalsaremainlyincli-
nationshape(Figure4B＆D).Inpitedvessel, they
posessamoreinclinedendwalandsomeperforations
inseveralsidesofwal.Somesurfacesofperforation
preservesomethreadlikeremnants(Figure4B).
Thediameterofannularandspiralvesselsis6.70
～ .62 μm, thediameterofpitedvesselsis10.16 ～
21.29 μm.
Someendwalofspiralvesselsposessainclina-
tionperforationplate, andthereareseverallargeperfo-
rationsintheplate(Figure4D).Thecelwalofpa-
renchymacelsuchaspalisadetissueofasimilating
tissuewhichonlyconsistofprimarywalarenotdis-
solvedbyenzymes, withoutanyperforationsinthecel
wal, thereforepreservetheirintegrityofmembrane-
likewal(Figure4C).
Fig.4　SEMphotographsofvesselelementsofpinnaofDoonedule
A:Severalspiralvesselelements, theirlateralwallhaveformsomeperforationswithsomethreadlikemembraneremnantsofprimary
wal.LP:Lateralwallperforation, PW:primarywall).B:Apittedvessel, therearesomeperforationwithsomethreadlikeormesh-
likemembraneremnantsconsistofprimarywallintheendwal.C:Theparenchymacellofpalisadetissueofassimilatingtissue, they
preservetheintegrityofmembranewalconsistofprimarywal.(PT:palisadetissue).D:Ascalariformvesselelementwhichpossesssomeperforationsinendwall
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中山大学学报 (自然科学版) 第 47卷　
Macrozamialongispina　Intheroot, scalariform,
pited, reticulateandreticulate-pitedvesselswereob-
served, andtheyaremorenearcircularandfewnear
polygonal.Someareneartheshapeofflat.Inpited
vessel, thereareseveralperforationsintheendwal
perforationplate(Figure5A), andtheperforation
plateisinclinationshape.Apartofpitedvesselare
nearflatshape, theperforationsinthetwosides, even
iftheendwalisalsothesituation, whileitshowa
twistingshape(Figure5 B).Thephenomenonis
widelyextantthatmoreperforationshaveformedinthe
lateralwalofavesselelement, andthereisstilvery
fewperforationsinanotherelementofpitedvessel, the
pitmembraneisstilpreserveentiremembraneinthe
outsideofvessel(Figure5B＆C).
Someendwalspossesssomereticularperfora-
tions, andtheinclinedperforationplatehaveatail
(Figure5C).Severaladjacentelementsofpitedand
scalariformveselshowedthephenomenonthatavessel
elementpreservestilthreadlikemembraneremnantof
primarywalintheperipheryofperforation, anothera
vesselelementhaveformedentireperforations(Figure
5D).Theresultindicatesthatthevesselelementdif-
ferentiationisnotasynchronousevenifinsametissue.
Thediameterofscalariform vesselis14.72 ～
19.41 μm, diameterofpitedvesselis12.87 ～ 24.22
μm, thewidthofpitedvesselofflatshapeis23.67 ～
25.96 μm, thediameterofreticularvesselis15.64 ～
22.79 μm.
Fig.5　SEMphotographsofvesselelementsofrootMacrozamialongispina
A:Apitedvesselelement, showingtheinclinedendwallperforationplatewithseveralperforationsintheplate.(EP:Endwal
perforationplate).B:Severalpittedvesselelements, showingaflatshapevesselelementwithsometwist.Anotheravesselelement
preservestilentiremembraneofprimarywallintheoutsideofvessel.(PM:Primarywalmembrane).C:Somepitedandretic-
ularvesselelements, toshowaperforationplateofendwal, withalitletail, theirlateralwallhavemoreperforationsandsomeves-
selelementspreservestilentiremembraneofprimarywallintheoutsideofvessel.D:Severalpitedandscalariformvesselele-
ments, therearesomeentireperforationsandsomethreadlikeorweblikemembranesstillremainintheperipheryofperforations
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　第 4期 黄玉源等:苏铁类植物 4个属的导管与被子植物导管结构特征的比较研究
Micheliaalba　Intheleafblade, thespiral, scalari-
formandpitedvesselwereseen, thespecieshavethe
distinctspecialtythatmanyvesselelementsareflat
shapeornearflat– bandshape.Insomescalariform
vesselelements, theendportionareflatlikeaslice
andacuteshape, thereiswithoutendwal, onlypos-
sessamargin, theirperforationsadjoineachotheronly
inlateralwalintwosidesorseveralsides, theseend
walhavenotinclinedplateintop(Figure6A＆B).
Thischaracterismoreprimitive.
Fig.6　SEMphotographsofvesselelementsofleafbladeofMicheliaalba
A:Severalscalariformvesselelements, showingtheirflatandbandvesselelementswithabendshape, theseendofelementshavenotendwall, onlyhaveperforationsinlateralwal;(LW:Lateralwall, PW:primarywall).B:Ascalariformvesselelement, to
showthenearendportionthereisatwistshapewithsomeperforationsinlateralwal, endisacuate, withoutendwal, onlyhaveamarge.C:Ascalariformvesselelement, showingtheflatandtwistshapeandwithouttopperforationplateinend, onlyhaving
someperforationsinthetwosidesoflateralwal.D:Aannalarandascalariformvesselelements, theirlateralwalhavesomeper-forations.(LP:Lateralwalperforation).E:Apitedvesselelementandsomeparenchymacelsonlyconsistofprimarywal
whichpreservetheirintegrityofwallofthinmembraneshape.Thevesselelementpossessaacuateendportion, theperforationslo-cateinseveralsidesoflateralwall.(PC:parenchymacel).F:Apitedvesselelement, toshowtheflatandbandshape, there
aremoreperfrationsinthetwosidesoflateralwal
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中山大学学报 (自然科学版) 第 47卷　
Thesescalarifrom perforationsdistributeinend
portionoflateralwalandothersites.Somevesselele-
mentsformedperforationonlyinasideortwosides,
butothersidehavenotperforationinlateralwal, stil
remainprimarywalonthesurfaceoflateralwal(Fig-
ure6A).Somescalariformvesselelementslikeaflat
bandshape, theirendportionisacute, withatwisting
shape, theirendportionhavenotalsoinclinedplatein
top, onlyhaveseverallateralwalsidestherearemany
perforations(Figure6C, F).Inthesitethereislonger
distencetoendportion, areformedmanyperforations
inthelateralwal.Someornamentationandlargeper-
forationscanbeseenontheinteriorwalofthevesels
(Figure6D＆ E).Thecelwalofparenchymacels
onlyconsistofprimarywalarenotdissolvedbyen-
zymes, whereforepreservetheirintegrityofwalofthin
membraneshape(Figure6E).
Thediameterofannularandspiralveselsis7.62
～ 8.79μm, thewidthofscalariformandpitedvessels
offlat– bandshapeis24.81 ～ 26.73 μm, thethick-
nessis8.74 ～ 12.62 μm;thediameterofscalariform
andpitedvesselsofnearpolygonalis12.21 ～
16.46μm.
AmygdaluspersicaIntheleafblade, manyan-
nular, spiralandreticularvesselswereobserved.The
spiralvesselhaveformedsomeperforationsinlateral
wal(Figure7A), andsomeendwalofreticularves-
selelementismoreinclinedshape.Thedegreeofin-
clinationisgreater, withsimpleperforationplateinits
endwalandwithalitletail, insomeveselelements
ofreticularvesselhaveformedsomereticularperfora-
tionsinlateralwal(Figure7B).
Thediameterofannularorspiralveselis8.72 ～
12.67 μm, thediameterofscalariformvesselis14.37
～ 20.64 μm, thediameterofreticularvesselis21.73
～ 28.62 μm.
Fig.7　SEMphotographsofvesselelementsofLeafbladeofAmygdaluspersica
A:Severalspiralvesselelements, theirlateralwallhavesomeperforations.B:Sveralreticularvesselelements, toshowthethein-
clinedendwallwithasimpleperforationplateandsomeperforationsintheirlateralwal
3　Discussion
Sameasangiosperm, thestructuraltypesofthe
vesselsofspeciesinfourgeneraoftwofamiliesofcy-
cadhaveaplentifulvariety, andconsistingofannular,
spiral, scalariform, reticulate, pitedvesselsandsca-
lariform-pitedandreticulate-pitedvesselsoftransi-
tionaltypes.
Theperforationplateofeveryendwalofcycads
isveryweldeveloped, havinglargeperforations.Some
multipleperforationplateshaveseveralquitelargeper-
forations, butonlyafewhavemorethantenperfora-
tions.Comparedwiththecharacteristicsofmanyspe-
ciesofthemoreprimitiveangiospermswhosevessel
endwalshavedozens, morethan100 andeven200
smalperforations[ 13, 15 -17 ] , thusstructuresofthecy-
cadsvesselspromotetherapidtransportoflargea-
mountswater, aswelasinorganicandessentialorgan-
icnutrients[ 18 ] .
Thetheoryofcomparativemorphologysuggests
thatmoreprimitivevesselsareinclinationandpossesa
clearlyandlongpointedtail.Conversely, thevessel
elementsaremoreevolvedandtheirendwalshave
gradualybecomehorizontalornearhorizontalandba-
sicalyhavenotatail[ 17, 19 ] .ComparewithMichelia
albaandAmygdaluspersica, cycadsvesselgeneralpos-
sessalesserinclinationdegreeofendwalperforation
plate, theirendwalaremorenearhorizontalthan
MicheliaalbaandAmygdaluspersica, indicatethat
thesevesselsofcycadsgeneraarethesituationofmore
advancedinthisindex.
Inthepast, sinceobservationislimitedinlight
microscope, onlyfocustolookwhetherhavelargesin-
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　第 4期 黄玉源等:苏铁类植物 4个属的导管与被子植物导管结构特征的比较研究
gleperforationwhichthenmanybarsbetweensome
smalperforationsdisappearandcombinetoalarge
perforationinperforationplateofendwal, therefore
everwidelythoughtthatfernismostprimitivevascular
plant, andtheyhavenotvessels.Butwithresearchin-
creaseandusedelectronmicroscope, vesselhasbeen
discoveredinfern, andgradualyincreasesfamilies
andgenera.Nowvesselshavebeendiscoveredinsome
fernswhichbethoughtmostprimitivetaxa, suchas
SelaginelageneraofSelaginelaceae, Equisetumgene-
raofEquisetaceaeandmoreevolutionarytaxonsuchas
PteridiumgeneraofPteridiaceae, Phylitisgeneraand
MarsileageneraofMarsilaeaceaeetc.[ 20-23 ] .There-
forethehighandwoodycycadsposessvesselisane-
cessitywhichplantadapttoenvironmentandnatural
evolutionalphenomenon.
ManyvesselsofMicheliaalbahavenottopplate
intheirendportion, onlyhaveacuteoralineshape
margininend, meansthattheywithoutendwal;end
portiononlyconsistofwidertwolateralwalofflatand
likebandshape, adjoinelementsofvesselconnect
eachotherrelyononlytheperforationswhichlocatein
theselateralwals, theirendismoreacuteorpoint.
Thesecharactersaremoreprimitivecharacterofves-
sel, thesefeaturesarehavenoseenreportinpast.
Pastviewpointbasicalythoughtthatvesselelements
certainlypreserveatopplateisveryinclination, more
inclination, nearhorizontalorhorizontal.Infact, the
phenomenonisexistencewhichvesselelementwithout
formedanyendwalorcaltopplateasevenifitis
veryinclination, adjoinningvesselelementsconnect
eachotherrelyontheperforationsofseverallateral
wals, andthusvesselisstilhavingalargeabilityin
conduction, evenexceedtheabilitywhichpossessonly
atopplateinendwalbecauseofseveralsidesurface
oflateralwalandtheirmoreorlargeperforations, fur-
thermorethusstructurecanserveaimportantaction
thatanvesselelementcanconnecttwotoseveralother
vesselelementsinlongitudinaldirection.Itistherea-
sonthatevenifthesefeaturesaremoreprimitivein
structure, theycanpreservestilinangiospermorcy-
cads.
Theresearchshowthesomevesselelementof
Micheliaalbaofangiospermandcycadpossesstwisting
shape, thisstructurecanmakeadjoinseveralvesselel-
ementsconnectinalitleshapeoftwisttogether, thus
structureprobablycanmakeitservewelconduction
andstrongercapabilityofmechanicalsupportinsame
time.
Inthisstudy, perforationscanbeseenonlyintra-
chea, thecelwalofparenchymacelsonlyconsistof
primarywalhavenotbeenseenanyperforation, indi-
catedthatenzymeactionarespecificitywhichonlyact
tointercelularlayer(middlelamela)ofthetissueof
trachearyelementsorparenchymacels, andnotmake
dissolvedactiontomembrane-likeprimarywal ,
whereforeparenchymacelspreserveintegrityofthin
membranewal.
Thetheoryofcomparativemorphologysuggests
thatsmalerdiametersofvessel, aremoreancestral
[ 24-27] .Presentresearchshowsthatthediameterof
vesselelementsofcycadsandtwogeneraofangiosperm
issameinsize, accountfortheextentofevolutionis
nearorsameintheindex.
Assameasmanyangiosperms[ 12, 13, 15 ] , thephe-
nomenonthatsomevesselelementsofcycadspreserve
stilthreadlikeormesh-likemembraneremnantofpri-
marywalintheperipheryofperforation, andcanseen
theprocessthatprimarywalgradualyformedsmalor
overahalfperforation, andthentheseremnantscom-
pletedisappearingformedlargeandentireperforation.
Becauseprimarywalofeverytrachearyelement
wrapinmostperipheryofthecel, afterwardthesec-
ondarywaloflignificationandcorkificationforminin-
sideprimarywal, andtheyformvariousornamenta-
tionssuchastheornamentationsofannular, scalari-
form, pited, reticulateandsometransitionaltypesof
scalariform-reticulateetc.locateininteriorlayerofpri-
marywal;ifthetrachearyelementispitedtracheidor
vesselelement, thepitcavityofsimpleorborderedpits
whichwereformedbysecondarywalarelocatedinin-
sideprimarywal, thesurfaceoftracheidorvesselele-
menthavenotpitorporeasentrance, becausethese
pitsperipherywrapalayermembraneofprimarywal
[ 2, 19, 28, 29 ] .intheplaceofbetweentwoadjoinedtrac-
hearyelementsisintercelularlayer(middlelamela)
consistofpectin, twotrachearyelementsdivorcefrom
thislayerthenexperimentaltreat[ 10 -11] .Thereforeif
thereisperforationintrachearyelement, itsstructure
whichwereseenin scanningelectronmicroscope
(SEM)isdarkanddeephole, ifthosesiteswithout
perforation, theprimarywalstilwrapinthecelsur-
face, thesewals structurewhichwereseeninSEM
arebrightandpreservedlevelandsmoothsurface.
Theresearchshowsthatlikemanyangiosperms,
inMicheliaalbaandAmygdaluspersicaandfourgenera
ofcycads, thelateralwalofthevesselelementspos-
sessperforations, andtheseperforationslinkupbe-
tweenvesselelementsinthesidesurface, sothatthese
elementsnotonlycommunicatelongitudinalyandhave
powerfullongitudinaltransportability, butalsohavea
strongcapabilityfortransportingwater, aswelasinor-
ganicandorganicnutrientsinatransverseplane[ 2, 19 ] .
Forexample, thelateralwalperforationsoftomato
85
中山大学学报 (自然科学版) 第 47卷　
(Lycopersiconesculentum)[ 30] .andsoon.
Themultipleperforationplatessuchasthescarali-
formperforationplateandthereticulateperforation
plateareprimitive, andfromthemevolvedthesimple
perforationplatethatpossessesonlyoneperforationin
theendwal[ 17, 19, 31] ..Thisresearchresultsshowed
thatsomespeciesofcycadshaveevolvedtoformsimple
perforationplatesinendwals, indicatingthattheves-
selsofcycadarequiteevolutionalyadvanced.
Veselsevolvedfrom tracheids, andtheyhave
formedmanyperforationsintheendwalandlateral
wal, sothevesselsareabletotransportaboutten
timesmorewaterandnutrientsthantracheidsinagiv-
enlengthoftime[ 31] Theplentifultypesofvesselsdis-
coveredinthesegeneraofcycads, andcomparewith
thevesseloftwofamiliesofangiosperm, therebycog-
nizedthelevelsofevolutionofcycadsvesselelement,
itisimportanttounderstandthemechanism which
thesemostprimitiveseedplantsextanthowtoadapted
toharshenvironmentsandrevealthesecrethowcycads
surviveandprocreateundergoafteraverylonggeolog-
icalperiod.
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86
　第 4期 黄玉源等:苏铁类植物 4个属的导管与被子植物导管结构特征的比较研究
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苏铁类植物 4个属的导管与被子植物导管结构特征的比较研究
黄玉源1, 2 , 廖文波 3 , 张宏达3 , 王佳卓 2 , 伍映辉 4
(1.仲恺农业工程学院生命科学学院 , 广东 广州 510225;2.广西大学农学院 , 广西 南宁 530005;
3.中山大学生命科学学院 , 广东 广州 510275;4.海口市农业科学研究所 , 海南 海口 570311 )
摘　要:对苏铁属的台湾苏铁 (Cycastaiwaniana)、 波温铁属的细齿波温铁 (Boweniaserrulata)、 双子铁属的双子铁
(Dioonedule)叶的羽片 , 大泽米铁属长刺大泽米铁 (Macrozamialongispina)的根 , 以及被子植物的白兰 (Micheliaalba)
和桃 (Amygdaluspersica)的叶组织进行了电子扫描显微镜的观察研究 , 结果表明 , 2个科 4个属苏铁植物的导管类型是丰
富的 , 导管的结构组成方式 、 发育过程与被子植物是一致的;例如导管端壁倾斜度等结构特征显示 , 一些被子植物导管的
结构比苏铁类植物的要原始。在被子植物的导管中有许多为端部呈扁平的带状 , 而且还带有扭曲状 , 没有端壁 , 只有两面
的侧壁及另两侧的很窄的边 , 在带状的侧壁上具有许多的穿孔。这在过去未见有报道。 对苏铁类植物导管的认识 , 对于我
们进一步了解现存最原始的种子植物对严酷环境的适应机制和进化状况 , 对于采取有效措施保护这些珍稀的植物类群 , 以
及对于结构植物学 、 植物进化和生态学等研究方面均具有重要的意义。
关键词:苏铁类植物;导管;被子植物;演化;结构特征;适应性
中图分类号:Q941;Q944.6
(上接第 76页)
ConstructionofChimericalFungalPhytaseanditsResistancetoProteolysis
CHENZhuang1, 2 , BEIJin-long2 , LIAOLing2 , LIUShi-gui1
(1.SchoolofLifeSciences, SichuanUniversity, Chengdu610064, China;
2.InstituteofAnimalScience, GuangdongAcademyofAgriculturalSciences, Guangzhou510640, China)
Abstract:ChimeraⅠ , Ⅱ andⅢ werecreatedbystepwisesubstitutionsofDNAfragmentsencodingregion1 -
47 , 178-237and338-381 fromAspergilusnigerNRRL3135phytase(Anp)genefortheircounterpartsinAs-
pergilusfumigatusphytase(Afp)gene, expressedinPichiapastoris, andthenpurified.Alchimeraandparent
phytasesresistedtopepsin.Afpandalchimeraslost13% ～ 23% phytaseactivitiesatm(trypsin) /m(phytase)
ratioof0.1 , whileAnpwasthoroughlyinactivated.However, SDS-PAGEoftrypsindigestionresultssuggested
seriousproteolysisofChimeraⅡ andⅢ.ButnondenaturingPAGEanalysisshowedtheystilkeptstructuralintact
innaturestateaftertrypsintreatment.ChimeraphtasesalsoposessednovelpHprofilesandthermostabilitydifer-
entfromAnpandAfp.Theseresultsdemonstratedthefeasibilityofimprovingfungalphytaseviagenefragmentre-
palcement.
Keywords:phytase;Aspergilusfumigatus;Aspergilusniger;proteolysis;proteinengineering
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