Mycorrhizal diversity in Apostasia Orchidaceae indicates the origin and evolution of orchid mycorr.docx
- 文档编号:27841037
- 上传时间:2023-07-05
- 格式:DOCX
- 页数:57
- 大小:565.64KB
Mycorrhizal diversity in Apostasia Orchidaceae indicates the origin and evolution of orchid mycorr.docx
《Mycorrhizal diversity in Apostasia Orchidaceae indicates the origin and evolution of orchid mycorr.docx》由会员分享,可在线阅读,更多相关《Mycorrhizal diversity in Apostasia Orchidaceae indicates the origin and evolution of orchid mycorr.docx(57页珍藏版)》请在冰豆网上搜索。
MycorrhizaldiversityinApostasiaOrchidaceaeindicatestheoriginandevolutionoforchidmycorr
AJBAdvanceAccess
PublishedonlineaheadofprintOctober23,2009;
doi:
10.3732/ajb.0900101
AmericanJournalofBotany
©2009BotanicalSocietyofAmerica,Inc.
MycorrhizaldiversityinApostasia(Orchidaceae)indicatestheoriginandevolutionoforchidmycorrhiza1
TomohisaYukawa2,5,6,YukiOgura-Tsujita2,5,RichardP.Shefferson3andJunYokoyama4
2TsukubaBotanicalGarden,NationalMuseumofNatureandScience,Tsukuba305-0005Japan3OdumSchoolofEcology,UniversityofGeorgia,Athens,Georgia30602USA4FacultyofScience,YamagataUniversity,Yamagata990-8560Japan
ABSTRACT
Wedemonstratedthat"orchidmycorrhiza,"aspecializedmycorrhizaltype,appearedinthecommonancestorofthelargestplantfamilyOrchidaceaeandthatthefungalpartnershiftedfromGlomeromycotatoaparticularcladeofBasidiomycotainassociationwiththischaracterevolution.Severaluniquemycorrhizalcharacteristicsmayhavecontributedtothediversificationofthefamily.However,theoriginoforchidmycorrhizaandthediversityofmycobiontsacrossorchidlineagesstillremainobscure.Inthisstudy,weinvestigatedthemycorrhizaeoffiveApostasiataxa,membersoftheearliest-divergingcladeofOrchidaceae.TheresultsofmolecularidentificationusingnrDNAITSandLSUregionsshowedthatApostasiamycorrhizalfungibelongtofamiliesBotryobasidiaceaeandCeratobasidiaceae,whichfallwithintheorderCantharellalesofBasidiomycota.MostmajorcladesinOrchidaceaealsoformmycorrhizaewithmembersofCantharellales,whilethesistergroupandothercloselyrelatedgroupstoOrchidaceae(i.e.,Asparagalesexceptfororchidsandthe"commelinid"families)ubiquitouslyformsymbioseswithGlomeromycotatoformarbuscularmycorrhizae.ThispatternofsymbiosisindicatesthatamajorshiftinfungalpartneroccurredinthecommonancestoroftheOrchidaceae.
KeyWords:
Apostasia•Asparagales•Basidiomycota•Botryobasidiaceae•Cantharellales•Ceratobasidiaceae•evolution•Orchidaceae•mycorrhiza
Orchidmycorrhiza
FromWikipedia,thefreeencyclopedia
Jumpto:
navigation,search
OrchidmycorrhizaareasymbioticrelationshipbetweentherootsofplantsofthefamilyOrchidaceaeandavarietyoffungi.Allorchidsaremycoheterotrophicatsomepointintheirlifecycle.Orchidmycorrhizaarecriticallyimportantduringorchidgermination,asorchidseedhasvirtuallynoenergyreserveandobtainsitscarbonfromthefungalsymbiont.Manyadultorchidsretaintheirfungalsymbionts,althoughthebenefitstotheadultphotosyntheticorchidandthefungusremainlargelyunexplored.
Fungiformingorchidmycorrhiza
Thefungithatformorchidmycorrhizaaretypicallybasidiomycetes.ThesefungicomefromarangeoftaxaincludingCeratobasidium(Rhizoctonia),Sebacina,TulasnellaandRussulaspecies.Someorchidsassociatewithsaprotrophic,orpathogenicfungi,whileotherorchidsassociatewithectomycorrhizalfungalspecies.Theselatterassociationsareoftencalledtripartateassociationsastheyinvolvetheorchid,theectomycorrhizalfungusandtheectomycorrhizalhostplant.
SymbioticCultureofTerrestrialOrchids
TerrestrialOrchidMycorrhizae
Theoverallmajorityoforchidseedsneedfungitogerminate.Allterrestrialorchidsarecharacterisedforhavingarelationshipwithfungithatliveinthesoil.Thehyphaecontacttherootswithoutdestroyingthemandthere'sanexchangeoforganicbuildingblocks-mainlycarbonandnitrogen.1)Thisisinitiatedinseedgerminationandcontinuesintoadulthood.
Thezygotethatresultedfrompollinationhastoundergoanumberofdivisionstocreatetheembryo.Thisfirstdivisionnormallytraversesthelengthoftheseed,creatingtwopoles:
oneatthetopwheregrowthhappensandoneatthebottomwithlookslikeastalk.Thisstalkiscalledthesuspensoranditsmainjobisabsorptionandthemanufactureofnutrientsfromtheendosperm-thenutritiousfoodreservethatenvelopestheembryoin“non-orchid”seeds.Thevastmajorityoforchidsdon'thaveanendosperm(exceptBletillastriata&Disauniflora),buttheydogrowsuspensorcells.
Whenthefungusbreaksintothetestaitpenetratestheembryoviathe(large)suspensorcell,growingitshyphaeinsidetheinnerembryoniccellsaslittlecoilscalledpeletons.Theorchidsimplydigeststhesepeletonsandthusreceivesnutrition.Withthisnewlyacquiredsourcetheorchidembryoincreasesinmasstoformtheprotocorm.Meanwhilethenumberofhyphaeenteringtheseedincreasesandwhenatippingpointisreachedtheprotocormdevelopsashootwithrootsandleaves.Atthispointthefungusinvadestheouter(cortical)cellsandstartsproducingpeletonsthere.Whentherootsbecomelargertheygrowroothairstoincreasethecontactsurfacebetweenrootandsoil(andfungus).
SwollenseedofOrchismasculainthesoilwithroothairsandhyphae,
aprerequisiteforgermination.
Alltuberousorchidsstartasasmallsphere.
ThefungalpartofthispartnershipistypicallyaspeciesofRhizoctonia(basidiomycota)thatplayalargeroleindecomposingcelluloseandorganicforestsoil2).It'sdifficulttodeterminewhatthefungusactuallybenefitsfromitsrelationshipwiththeorchid,forthisreasonitisoftensaidthattheorchidisaparasiteonthefungus.Theorchiddigeststhepeletonsasacarbonsourceuntilthechlorophyllintheleaveshavedeveloped,thiscantakefrommonthstoaneternityassomeorchidsneverbuildchlorophyll.Dependencyonthefunguscandecimateoncetheorchidreachesmaturity.Especiallyepiphyticorchidsareknownforlosingtheneedforpeletons,terrestrialorchidstypicallykeeptherelationshipgoinguntildeathdoesthempart.3)4)
Aswithjustaboutanythinginnature,thereisagradient.Gastrodiasesamoides(thePotatoOrchid),Dipodiumpunctatum(theSpottedHyacinthOrchid)andthetwospeciesofthegenusRhizanthella(RhizanthellagardneriandRhizanthellaslateri)alllackchlorophyll.Thismakesitimpossibleforthemtocapturetheenergyofsunlightdirectlyviaphotosynthesis,theycan'ttaptheenergysourceotherplantsrelyonforusingCO2asasourceofcarbon.Thesespeciesachievethisbyrelyingonafungusforthis,makingthem100%dependentontheirpartnerfortheirentirelife.TheOrchidaceaecontainabout200achlorophyllousspecies,whichobtaintheirCandmineralnutritioncompletelyfromsymbioticfungi,andarethereforecalledmycoparasitic,mycotrophicormyco-heterotrophic5).Initially,nearlyallorchidsaremyco-heterotrophic,butsomeneverdevelopleavesandlosethephotosyntheticfunction.
Orchidgeneraandspecieswhichdependheavilyonthesymbiont
Aphyllorchis-SEAsia,Indomalaysia:
A.caudata,A.prainii,A.unguiculata
Corallorhiza-northtemperateregions;Europe(1sp.),E.NorthAmericatoGuatemala:
C.maculata,C.mertensiana,C.striata,C.striatavar.vreelandii,C.trifida,C.wisteriana
Cymbidium:
C.macrorhizonofJapan
Cyrtosia-Indomalaysia(relatedtoGaleola):
C.javanica
Cystorchis-ChinaandAsia.OnlyC.aphyllamycotrophic
Didymoplexis-OldWorldtropicsexceptW.AfricaandIndia:
D.pallensinJapan
Cephalanthera:
C.austinae
Epipogium-temperateEurasia:
E.aphyllum,E.roseum
Eulophia-tropical:
E.zolingeri
Galeola-Madagascar,IndomalaysiatoAustralia:
G.nudifolia,G.septentrionalis
Gastrodia-EAsia,IndomalaysiatoNewZealand,Australia:
G.confusa,G.elata,G.lacista,G.nipponica,G.procera,G.pubilabiata,G.sesamoides,G.siamensis
Hexalectris-USandMexico:
H.nitida,H.spicata,H.spicata,H.warnockii
Lecanorchis-IndomalaysiatoJapan:
L.nigricans,L.trachycaula,L.trachycaula,L.sp.1.(Japan)
Limodorum-MediterraneanandEuropetoIran:
L.abortivum
Neottia-temperateEurasia:
N.nidus-avis
Pterostylis-Australia,MalaysiatoNewCaledonia.Onlysomemycotrophic.
Rhizanthella-SWandEAustralia:
R.gardneri,R.slateri
Stereosandra-ofSEAsiaandWMalaysia:
S.javanica
Stigmatodactylus-EAsiatoMalaysia:
S.sikokianus
Wullschlaegelia-tropicalAmerica:
W.calcarata
Yoania-HimalayasandJapan:
Y.amagiensis,Y.japonica
AfewspeciesofDisafromSouthAfricaontheotherhandcanbegerminatedonpuresphagnummosswithoutafungus.Inotherwords,thereareterrorchidsthatcouldn'tbebotheredlessaboutfungi,therearethosethatcouldn'tlivewithout,butmostofthemfallsomewherein-between.Thisbizarrelationshipisconsideredtobeoneofthereasonswhyorchidsproduceahumongousamountoftinydust-likeseeds:
sincethefungusprovidestheseedlingwithnourishment,theplantsaren'trequiredtopacktheseedswithstarchesandsugarslikeinotherplantstogettheiroffspringthroughthefirstdaysofgermination.Otherplantsneedtoprovidethisreservesothattheseedlingcandevelopitsfirstleavesandroots,fromthatpointontheseedlingreliesonitsrootsandleavestogetorganicresourcesandenergy.Orchidseedsaretinyandlackthebuilt-innutritionofbiggerseeds;orchidsthenpassthroughanongreen(“achlorophyllous”)developmentalstagewhentheycannotusefats,breakdownstarch,obtainphosphatesorphotosynthesise,andthereforerelyonanexternalsource.Thisisprovidedeitherbymanintheformofsimplecarbon-containingfoodsinsterileseedgermination,orbyafunguswhichbreaksdowncomplexcompoundsintosimpleronesinsymbioticgermination.Thefungalhyphaepenetratethetestaoftheseedandenterseitherthroughepidermalhairsorthesuspensoroftheundifferentiatedembryoviathebaseendoftheseed.Throughinvaginationoftheplasmamenbranethehyphaeenterthecellsandcoilin
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- Mycorrhizal diversity in Apostasia Orchidaceae indicates the origin and evolution of orchid mycorr
![提示](https://static.bdocx.com/images/bang_tan.gif)
链接地址:https://www.bdocx.com/doc/27841037.html