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Wat word daardie groot plante / swamme op bome genoem?

Wat word daardie groot plante / swamme op bome genoem?


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Ek het hulle in Augustus 2015 in Skotland gesien:

Die plante / swamme was redelik hoog (meer as 2m) op die boom. Hulle is amper sirkelvormig as jy hulle van bo af sien, skat ek (behalwe vir die deel waar hulle aan die boom gekoppel is). Ek dink die deursnee van hulle kan meer as 14 cm wees.

Wat word hulle genoem?


Wel, ek sal saamstem met fileunderwater, dit is 'n Fomes woedend. Vir meer inligting kyk hierdie: Fomes fomentarius is 'n taai meerjarige poliepoor wat gewoonlik met ouderdom hoefvormig word; dit word gevind op staande en vallende hardehout. Sy houtagtige boonste oppervlak ontwikkel gryserige sones, en sy bruin porie-oppervlak het klein ronde porieë. Wanneer dit oopgesny word (geen maklike taak, gegewe die taaiheid daarvan), bestaan ​​dit gewoonlik meer uit vaag gelaagde buise as vleis.

Saam met Piptoporus betulinus, Fomes fomentarius is een van twee sampioene wat die Tiroolse Ysman sowat 5000 jaar gelede gedra het. Hy het glo gebruik Fomes fomentarius as tinder.

Beskrywing:

Ekologie: Parasities en saprobies op die hout van hardehout (veral berke en beuke); wat 'n witvrot veroorsaak; alleen of saam groei; meerjarige; taamlik wydverspreid in noordelike en noord-gematigde Noord-Amerika

Dop: Tot ongeveer 20 cm deursnee; dopvormig tot hoefvormig; met 'n dowwe, houtagtige boonste oppervlak wat met grys en bruingrys gesoneer is.

Porie Oppervlak: Bruinerig; 2-5 ronde porieë per mm; buislae onduidelik, bruin, word gevul met witterige materiaal.

Stam: Afwesig.

Vlees: Bruinerig, dun, hard.


Selstruktuur en funksie

Swamme is eukariote en het as sodanig 'n komplekse sellulêre organisasie. As eukariote bevat swamselle 'n membraangebonde kern. 'n Paar soorte swamme het strukture wat vergelykbaar is met die plasmiede (lusse van DNS) wat in bakterieë gesien word. Swamselle bevat ook mitochondria en 'n komplekse stelsel van interne membrane, insluitend die endoplasmiese retikulum en Golgi-apparaat.

Swamselle het nie chloroplaste nie. Alhoewel die fotosintetiese pigment chlorofil afwesig is, vertoon baie swamme helder kleure, wat wissel van rooi tot groen tot swart. Die giftige Amanita muscaria (vlieëzwam) is herkenbaar aan sy helderrooi doppie met wit kolle ([Figuur 2]). Pigmente in swamme word met die selwand geassosieer en speel 'n beskermende rol teen ultravioletstraling. Sommige pigmente is giftig.

Figuur 2: Die giftige Amanita muscaria is inheems aan die gematigde en boreale streke van Noord-Amerika. (krediet: Christine Majul)

Soos plantselle, word swamselle deur 'n dik selwand omring, maar die rigiede lae bevat die komplekse polisakkariede chitien en glukaan en nie sellulose wat deur plante gebruik word nie. Chitien, wat ook in die eksoskelet van insekte voorkom, gee strukturele sterkte aan die selwande van swamme. Die selwand beskerm die sel teen uitdroging en roofdiere. Swamme het plasmamembrane soortgelyk aan ander eukariote, behalwe dat die struktuur gestabiliseer word deur ergosterol, 'n steroïedmolekule wat funksioneer soos die cholesterol wat in dierselmembrane voorkom. Die meeste lede van die koninkryk Fungi is nie-beweeglik. Flagella word slegs deur die gamete in die primitiewe afdeling Chytridiomycota geproduseer.


Plantaanpassings by Lewe op Land

Soos organismes aanpas by lewe op land, het hulle te doen met verskeie uitdagings in die terrestriële omgewing. Water is beskryf as &ldquotdie dinge van die lewe.&rdquo Die sel&rsquos binnekant&mdash die medium waarin die meeste klein molekules oplos en diffundeer, en waarin die meerderheid van die chemiese reaksies van metabolisme plaasvind&mdashis 'n waterige sop. Uitdroging, of uitdroging, is 'n konstante gevaar vir 'n organisme wat aan lug blootgestel word. Selfs wanneer dele van 'n plant naby 'n bron van water is, sal hul lugstrukture waarskynlik uitdroog. Water verskaf dryfkrag aan organismes wat in akwatiese habitatte woon. Op land moet plante strukturele ondersteuning ontwikkel in lug&mdasha-medium wat nie dieselfde lig gee nie. Daarbenewens moet die manlike gamete die vroulike gamete bereik deur nuwe strategieë te gebruik omdat swem nie meer moontlik is nie. Laastens moet beide gamete en sigote beskerm word teen uitdroging. Die suksesvolle landplante het strategieë ontwikkel om al hierdie uitdagings te hanteer, hoewel nie alle aanpassings gelyktydig verskyn het nie. Sommige spesies het nie ver van 'n akwatiese omgewing af beweeg nie, terwyl ander die water verlaat het en voortgegaan het om die droogste omgewings op aarde te verower.

Om hierdie oorlewingsuitdagings te balanseer, bied lewe op land verskeie voordele. Eerstens is sonlig volop. Op land word die spektrale kwaliteit van lig wat deur die fotosintetiese pigment, chlorofil, geabsorbeer word, nie deur water of mededingende fotosintetiese spesies in die waterkolom hierbo uitgefiltreer nie. Tweedens is koolstofdioksied meer geredelik beskikbaar omdat die konsentrasie daarvan hoër is in lug as in water. Boonop het landplante voor landdiere ontwikkel, dus totdat droë land deur diere gekoloniseer is, het geen roofdiere die welstand van plante bedreig nie. Hierdie situasie het verander namate diere uit die water opgekom het en oorvloedige bronne van voedingstowwe in die gevestigde flora gevind het. Op hul beurt het plante strategieë ontwikkel om predasie af te weer: van stekels en dorings tot giftige chemikalieë.

Die vroeë landplante het, soos die vroeë landdiere, nie ver van 'n oorvloedige bron van water geleef nie en het oorlewingstrategieë ontwikkel om droogte te bekamp. Een van hierdie strategieë is droogtetoleransie. Mosse kan byvoorbeeld uitdroog tot ’n bruin en bros mat, maar sodra reën water beskikbaar stel, sal mosse dit opsuig en hul gesonde, groen voorkoms herwin. Nog 'n strategie is om omgewings met hoë humiditeit te koloniseer waar droogtes ongewoon is. Varings, 'n vroeë afstamming van plante, floreer in klam en koel plekke, soos die onderlaag van gematigde woude. Later het plante wegbeweeg van akwatiese omgewings deur weerstand teen uitdroging, eerder as verdraagsaamheid, te gebruik. Hierdie plante, soos die kaktus, verminder waterverlies tot so 'n mate dat hulle in die droogste omgewings op aarde kan oorleef.

Benewens aanpassings spesifiek vir lewe op land, vertoon landplante aanpassings wat verantwoordelik was vir hul diversiteit en oorheersing in terrestriële ekosisteme. Vier groot aanpassings word in baie landplante aangetref: die afwisseling van generasies, 'n sporangium waarin spore gevorm word, 'n gametangium wat haploïede selle produseer, en in vaatplante, apikale meristeemweefsel in wortels en lote.

Afwisseling van generasies

Afwisseling van generasies beskryf 'n lewensiklus waarin 'n organisme beide haploïede en diploïede meersellige stadiums het (Figuur 14.1.1).

Figuur 14.1.1: Afwisseling van generasies tussen die haploïede (1n) gametofiet en diploïede (2n) sporofiet word getoon. (krediet: wysiging van werk deur Peter Coxhead)

Haplonties verwys na 'n lewensiklus waarin daar 'n dominante haploïede stadium is. Diplonties verwys na 'n lewensiklus waarin die diploïede stadium die dominante stadium is, en die haploïede chromosoomgetal slegs vir 'n kort tydjie in die lewensiklus tydens seksuele voortplanting gesien word. Mense is byvoorbeeld diplonties. Die meeste plante vertoon afwisseling van generasies, wat as haplodiplonties beskryf word: die haploïede meersellige vorm bekend as 'n gametofiet word in die ontwikkelingsvolgorde gevolg deur 'n meersellige diploïede organisme, die sporofiet. Die gametofiet gee aanleiding tot die gamete, of voortplantingselle, deur mitose. Dit kan die mees voor die hand liggende fase van die lewensiklus van die plant wees, soos in die mosse, of dit kan in 'n mikroskopiese struktuur voorkom, soos 'n stuifmeelkorrel in die hoër plante (die kollektiewe term vir die vaatplante). Die sporofietstadium is skaars waarneembaar by laer plante (die versamelnaam vir die plantgroepe mosse, lewermosse en horingblare). Toringbome is die diplontiese fase in die lewensiklusse van plante soos sequoias en denne.

Sporangia in die pitlose plante

Die sporofiet van pitlose plante is diploïed en spruit uit singamie of die samesmelting van twee gamete (Figuur 14.4.1). Die sporofiet dra die sporangia (enkelvoud, sporangium), organe wat die eerste keer in die landplante verskyn het. Die term &ldquosporangia&rdquo beteken letterlik &ldquospore in 'n vaartuig,&rdquo, aangesien dit 'n voortplantingssak is wat spore bevat. Binne die meersellige sporangia produseer die diploïede sporosiete, of moederselle, haploïede spore deur meiose, wat die 2 verminder.n chromosoomgetal tot 1n. Die spore word later deur die sporangia vrygestel en versprei in die omgewing. Twee verskillende tipes spore word in landplante geproduseer, wat lei tot die skeiding van geslagte op verskillende punte in die lewensiklus. Saadlose nievaskulêre plante (meer gepas na verwys as &ldquoseedlose nievaskulêre plante met 'n dominante gametofietfase&rdquo) produseer slegs een soort spoor, en word homospories genoem. Nadat dit uit 'n spoor ontkiem het, produseer die gametofiet beide manlike en vroulike gametangia, gewoonlik op dieselfde individu. Daarteenoor produseer heterosporiese plante twee morfologies verskillende tipes spore. Die manlike spore word mikrospore genoem as gevolg van hul kleiner grootte sal die relatief groter megaspore in die vroulike gametofiet ontwikkel. Heterosporie word waargeneem in 'n paar pitlose vaatplante en in alle saadplante.

Wanneer die haploïede spoor ontkiem, genereer dit 'n meersellige gametofiet deur mitose. Die gametofiet ondersteun die sigoot wat gevorm word uit die samesmelting van gamete en die gevolglike jong sporofiet of vegetatiewe vorm, en die siklus begin nuut (Figuur 14.4.2 en Figuur 14.4.3).

Figuur 14.4.2: Hierdie lewensiklus van 'n varing toon afwisseling van generasies met 'n dominante sporofietstadium. (krediet "fern": wysiging van werk deur Cory Zanker krediet "gametophyte": wysiging van werk deur "Vlmastra"/Wikimedia Commons) Figuur 14.4.3: Hierdie lewensiklus van 'n mos toon afwisseling van generasies met 'n dominante gametofietstadium. (krediet: wysiging van werk deur Mariana Ruiz Villareal)

Die spore van saadlose plante en die stuifmeel van saadplante word omring deur dik selwande wat 'n taai polimeer bekend as sporopollenien bevat. Hierdie stof word gekenmerk deur lang kettings van organiese molekules wat verband hou met vetsure en karotenoïede, en gee die meeste stuifmeel sy geel kleur. Sporopollenien is buitengewoon bestand teen chemiese en biologiese afbraak. Die taaiheid daarvan verklaar die bestaan ​​van goed bewaarde fossiele van stuifmeel. Sporopollenien is eens gedink om 'n innovasie van landplante te wees, maar die groen alge Coleochaetes is nou bekend om spore te vorm wat sporopollenien bevat.

Beskerming van die embrio is 'n groot vereiste vir landplante. Die kwesbare embrio moet teen uitdroging en ander omgewingsgevare beskerm word. In beide saadlose en saadplante verskaf die vroulike gametofiet voeding, en by saadplante word die embrio ook beskerm soos dit in die nuwe generasie sporofiet ontwikkel.

Gametangia in die pitlose plante

Gametangia (enkelvoud, gametangium) is strukture op die gametofiete van pitlose plante waarin gamete deur mitose geproduseer word. Die manlike gametangium, die antheridium, stel sperm vry. Baie pitlose plante produseer sperm wat met flagella toegerus is wat hulle in staat stel om in 'n klam omgewing na die archegonia, die vroulike gametangium, te swem. Die embrio ontwikkel binne die argegonium as die sporofiet.

Apikale Meristeme

Die lote en wortels van plante neem in lengte toe deur vinnige seldeling binne 'n weefsel wat die apikale meristeem genoem word (Figuur 14.1.4). Die apikale meristeem is 'n dop van selle by die lootpunt of wortelpunt gemaak van ongedifferensieerde selle wat deur die hele lewe van die plant voortplant. Meristematiese selle gee aanleiding tot al die gespesialiseerde weefsels van die plant. Verlenging van die lote en wortels laat 'n plant toegang tot bykomende spasie en hulpbronne: lig in die geval van die loot, en water en minerale in die geval van wortels. ’n Aparte meristeem, wat die laterale meristeem genoem word, produseer selle wat die deursnee van stamme en boomstamme vergroot. Apikale meristeme is 'n aanpassing om vaatplante toe te laat om te groei in rigtings wat noodsaaklik is vir hul oorlewing: opwaarts tot groter beskikbaarheid van sonlig, en afwaarts in die grond om water en noodsaaklike minerale te verkry.

Figuur 14.1.4: Hierdie appelsaailing is 'n voorbeeld van 'n plant waarin die apikale meristeem aanleiding gee tot nuwe lote en wortelgroei.


Hoe swamme bome help om droogte te verdra

Die mutualistiese verhouding tussen boomwortels en ektomikorrisale (ECM) swamme vorm bos-ekosisteme sedert hul ontstaan. ECM-swamme is sleutelspelers wat die groei, gesondheid en stresverdraagsaamheid van woudbome wêreldwyd ondersteun, soos eikebome, denne, sparre, berk en beuk, en help om die produktiwiteit van bio-energie-grondstofbome, insluitend populier en wilgerboom, te bevorder. Die mees algemene ECM-swam is Cenococcum geophilum, gevind in subtropiese deur arktiese sones en veral in uiterste omgewings. Dit is ook die enigste mikorisale swam in die Dothideomycetes, 'n groot klas wat bestaan ​​uit sowat 19 000 swamspesies, baie van hulle plantpatogene.

Om meer te wete te kom oor watter ektomikorrisale kenmerke dominant is in Cenococcum geophilum, 'n span gelei deur navorsers by die Franse Nasionale Instituut vir Landbounavorsing (INRA) en die Switserse Federale Instituut vir Bos-, Sneeu- en Landskapnavorsing WSL, en insluitend navorsers by die Amerikaanse departement van Energy Joint Genome Institute (DOE JGI), 'n DOE Office of Science User Facility, het sy genoom vergelyk met die genome van nabye familielede Lepidopterella palustris en Glonium stellatum, nie een van hulle is ECM-swamme nie. Die studie is op 7 September aanlyn gepubliseer Natuur kommunikasie. Hulle het spesifieke aanpassings gevind in die C. geophilum transkriptoom &nie- die stel van sy boodskapper-RNA-molekules wat werklike biochemiese aktiwiteit deur die swam weerspieël &nie-wat kan help om hul gashere meer weerstand te bied teen droogtestres, 'n bevinding wat nuttig kan wees om meer plantvoedingstowwe vir bio-energie te ontwikkel te midde van die veranderende klimaat.

As deel van 'n vergelykende genomiese analise gedoen deur die Mycorrhizal Genomics Initiative (MGI) onder leiding van studie senior skrywer Francis Martin van INRA, die DOE JGI C. geophilum en sy nabye familielid Lepidopterella palustris, en beide hierdie genome en 'n ander nabye familielid geannoteer, Glonium stellatum. “Ons het gewys dat die genoom van C. geophilum, die enigste bekende mikorisa-simbiont binne die grootste swamklas Dothideomycetes, het oor generasies dieselfde genomiese aanpassings aan die mikorisale lewenstyl verkry as die voorheen opeenvolgende ektomykorrisale basidiomisete," het Martin gesê. "Dit sluit in 'n opvallend verminderde aantal plantselwand-afbrekende ensieme (PCWDE) ) en 'n groot stel simbiose-geïnduseerde afkoms-spesifieke gene, insluitend dosyn van mikoriza-geïnduseerde klein afgeskeide effektor-agtige proteïene (MiSSPs)."Anders as vrylewende saprotrofe, swamme wat hul voedingstowwe kry deur organiese materiaal in woudgronde te ontbind en vereis dus PCWDE's, Cenococum het sterk op sy gashere staatgemaak vir sy koolstofvoeding.

Sleutelgene vir droogteaanpassing gevind

Let op dat die wortelpunte van C. geophilum hoogs bestand teen uitdroging is, is een van die span se sleutelbevindinge dat twee van die drie mees geïnduseerde C. geophilum gene in simbiose kodeer vir waterkanale. "Die regulering van hierdie waterkanaalgene is fyn ingestel onder droogtetoestande en hulle kan dus 'n sleutelrol speel in die droogte-aanpassing van gasheerplante," het eerste skrywer Martina Peter van die Switserse Federale Navorsingsinstituut WSL gesê.

"C. geophilum bevolkingsgenomika moet lig werp op die meganismes van gasheer- en omgewingsaanpassing," het die span in hul referaat geskryf. "Dit moet die identifisering van droogte-aangepaste fasiliteer C. geophilum stamme, wat gebruik kan word om hul gasheerbome doeltreffend te ondersteun wat deur die voorspelde toename in droogteperiodes in baie dele van die wêreld bedreig word."

Beide Peter en Martin het opgemerk dat krediet vir die sukses van die werk en van die Mycorrhizal Genomics Initiative toekom aan die "nuwe samewerking" tussen hul spanne, die DOE JGI, Joey Spatafora by Oregon State University en Pedro Crous CBS Fungal Biodiversity Centre (Utrecht, Nederland) sowel as met Bernard Henrissat van CNRS en Universiteit van Aix-Marseille.

“Die kruising van genomika en evolusionêre biologie, soos uitgevoer in die MGI en die 1000 Fungal Genomes (KFG)-projek, kan ons begrip van die biologiese beginsels intrinsiek aan mikorisale simbiose inlig,” het Martin gesê. "Deur genoomvolgordes te kombineer met streng fisiologiese en ekologiese studies, gaan ons 'n tyd binne waar die koppeling van die teenwoordigheid, samestelling en oorvloed van grondmikorisale gemeenskappe met belangrike grondprosesse en woudproduktiwiteit op 'n ekosisteemskaal moontlik is."


Hoe swamme voeding kry

Soos diere, is swamme heterotrofe: Hulle gebruik komplekse organiese verbindings as 'n bron van koolstof eerder as om koolstofdioksied uit die atmosfeer te bind, soos sommige bakterieë en die meeste plante doen. Daarbenewens bind swamme nie stikstof uit die atmosfeer nie. Soos diere moet hulle dit uit hul dieet verkry. Maar anders as die meeste diere wat kos inneem en dit dan intern in gespesialiseerde organe verteer, voer swamme hierdie stappe in die omgekeerde volgorde uit. Vertering gaan inname vooraf. Eerstens word eksoënsieme, ensieme wat reaksies op verbindings buite die sel kataliseer, uit die hifes vervoer waar hulle voedingstowwe in die omgewing afbreek. Dan word die kleiner molekules wat deur die uitwendige vertering geproduseer word deur die groot oppervlaktes van die miselium geabsorbeer. Soos met dierselle, is die swambergingspolisakkaried glikogeen eerder as stysel, soos dit in plante voorkom.

Swamme is meestal saprobes, organismes wat voedingstowwe uit verrottende organiese materiaal verkry. Hulle verkry hul voedingstowwe uit dooie of ontbindende organiese materiaal, hoofsaaklik plantmateriaal. Swam-eksoënsieme is in staat om onoplosbare polisakkariede, soos die sellulose en lignien van dooie hout, af te breek tot maklik opneembare glukosemolekules. Ontbinders is belangrike komponente van ekosisteme, omdat hulle voedingstowwe wat in dooie liggame opgesluit is, terugstuur na 'n vorm wat vir ander organismes bruikbaar is. Hierdie rol word later in meer besonderhede bespreek. As gevolg van hul uiteenlopende metaboliese weë, vervul swamme 'n belangrike ekologiese rol en word dit ondersoek as potensiële hulpmiddels in bioremediëring. Sommige soorte swamme kan byvoorbeeld gebruik word om dieselolie en polisikliese aromatiese koolwaterstowwe af te breek. Ander spesies neem swaar metale soos kadmium en lood op.


Bome Praat Met mekaar. 'Moederboom'-ekoloog hoor ook lesse vir mense

Suzanne Simard is 'n professor in woudekologie aan die Universiteit van Brits-Columbië. Haar eie mediese reis het haar navorsing geïnspireer oor onder meer die manier waarop taxusbome chemies met naburige bome kommunikeer vir hul wedersydse verdediging. Brendan George Ko/Penguin Random House steek onderskrif weg

Suzanne Simard is 'n professor in woudekologie aan die Universiteit van Brits-Columbië. Haar eie mediese reis het haar navorsing geïnspireer oor onder meer die manier waarop taxusbome chemies met naburige bome kommunikeer vir hul wedersydse verdediging.

Brendan George Ko/Penguin Random House

Bome is "sosiale wesens" wat op samewerkende maniere met mekaar kommunikeer wat ook lesse vir mense inhou, sê ekoloog Suzanne Simard.

Simard het in Kanadese woude grootgeword as 'n afstammeling van houtkappers voordat hy 'n bosbou-ekoloog geword het. Sy is nou 'n professor in bos-ekologie aan die Universiteit van Brits-Columbië.

Bome word aan naburige bome gekoppel deur ’n ondergrondse netwerk van swamme wat soos die neurale netwerke in die brein lyk, verduidelik sy. In een studie het Simard gekyk hoe 'n Douglas-spar wat deur insekte beseer is, chemiese waarskuwingseine stuur na 'n ponderosa-denne wat daar naby groei. Die denneboom het toe verdedigingsensieme geproduseer om teen die insek te beskerm.

"Dit was 'n deurbraak," sê Simard. Die bome het "inligting gedeel wat eintlik belangrik is vir die gesondheid van die hele woud."

Benewens die waarskuwing van mekaar van gevaar, sê Simard dat bome bekend is dat hulle op kritieke tye voedingstowwe deel om mekaar gesond te hou. Sy sê die bome in 'n woud word dikwels aan mekaar gekoppel via 'n ouer boom wat sy 'n "moeder" of "hub"-boom noem.

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"In die verbinding met al die bome van verskillende ouderdomme, kan [die moederbome] eintlik die groei van hierdie ondergrondse saailinge fasiliteer," sê sy. "Die saailinge sal by die netwerk van die ou bome aansluit en baat vind by daardie groot opname-hulpbronkapasiteit. En die ou bome sal ook 'n bietjie koolstof en voedingstowwe en water na die klein saailinge deurlaat, op deurslaggewende tye in hul lewens, wat help hulle eintlik om te oorleef."

Die studie van bome het vir Simard nuwe aanklank gekry toe sy met borskanker gediagnoseer is. In die loop van haar behandeling het sy uitgevind dat een van die chemoterapiemedisyne waarop sy staatgemaak het, eintlik afkomstig is van 'n stof wat sommige bome maak vir hul eie wedersydse verdediging. Sy verduidelik haar navorsing oor samewerking en simbiose in die bos, en deel haar persoonlike storie in die nuwe memoires Vind die Moederboom: Ontdek die wysheid van die bos.

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Sy het in haar 20's vir 'n houtkapmaatskappy in British Columbia gewerk

Dit was die laat 1970's toe ek begin het hulle was skoonkap en het net begin om bome te plant. En so was dit natuurlik heeltemal anders as wat ek my oupa en my pa en ooms sien doen het. Hulle het net hier en daar die vreemde boom uitgehaal. Maar dit was groothandel om al die bome uit te haal, die grotes en die kleintjies. En dit was my eerste werk in die bosbedryf, wat vir my nogal skokkend was. Maar dit was ook uiters opwindend omdat dit so gevaarlik was. En ek was ook een van die eerste meisies wat in die bedryf was.

Om 'n jong bosbouer te wees en te besef dat swam die sleutel tot die gesondheid van 'n bos was

In die bosvloer. daar is allerhande soorte goggas, maar daar is ook baie swamme. En die swamme is so kleurvol. Daar is geel en pers en wit en . hulle groei reg deur die woudvloer tot op die punt waar dit soort van gaas lyk, amper. En so het ek hierdie geel swam gekry. En tog, toe ek die saailinge optrek wat nie so goed vaar nie - hulle was geel en vrek - het ek besef dat hul wortels soort van swart en reguit was. . En so het ek gewonder, wat het hulle gemis? Het hulle hierdie swam gemis? Was hierdie swam . 'n patogeen of was dit 'n helperswam?

En uiteindelik het ek geleer dat dit 'n spesiale soort helperswam is wat 'n mikorisa-swam genoem word - wat net beteken dat die swam die tipe is wat deur die grond groei en voedingstowwe en water optel en dit terugbring na die saailing. . So uiteindelik kon ek saamstel dat hierdie klein plantjies wat nie so goed vaar nie, hul mikorisale swamme mis.

Omgewing En Energie Samewerkend

Klimaatsverandering en ontbossing beteken dat die aarde se bome jonger en korter is

Oor die kritieke verhouding tussen bome en swamme

Hou in gedagte dat alle bome en alle plante - behalwe vir 'n baie klein handjievol plantfamilies - verpligte verhoudings met hierdie swamme het. Dit beteken dat hulle hulle nodig het om te oorleef en te groei en keëls te produseer en fiksheid te hê - met ander woorde, om hul gene na die volgende generasies te dra. En die swamme is afhanklik van die plant of die bome. omdat hulle self nie blare het nie [vir fotosintese]. En so betree hulle hierdie simbiose deurdat hulle saam in die wortel woon, en hulle verruil hierdie noodsaaklike hulpbronne: koolhidrate van die plant vir voedingstowwe van die swam, in hierdie tweerigting-uitruiling wat baie styf is, amper soos 'n markruil. As jy my vyf dollar gee, gee ek jou vyf dollar terug. Dit is baie, baie streng gereguleer tussen daardie twee vennote in die simbiose. Maar, ja, alle bome en alle plante in al ons woude regoor die wêreld is afhanklik van hierdie verhouding.

Oor hoe bome mekaar kan help deur voedingstowwe te deel

[Destyds] is berke as onkruid beskou. Daar was 'n groot program om hierdie bome te bespuit en te onkruiddoder om van hulle ontslae te raak, want die bosbouers het die berke as mededingend met Douglas-spar beskou, wat veral om lig meeding. Ek het egter in hierdie plantasies waargeneem dat wanneer hulle die berke uitroei, wanneer hulle dit gespuit of gesny het, dat daar 'n siekte in die woude was wat net soos 'n vuur sou begin versprei. Dit is Armillaria-wortelsiekte genoem. Ek het regtig gedink, ons doen iets verkeerd hier. En daarom wou ek weet of die berke op een of ander manier die sparre teen hierdie siekte beskerm en dat wanneer ons hulle uitsny, dit dit eintlik veel erger gemaak het.

Die Coronavirus Krisis

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Ek het geleer van hierdie mikorisa-swamme en hoe hulle bome eintlik teen siektes kan beskerm. En ek het ook gehoor van David Reed se werk in die VK, waar hy in die laboratorium gewys het dat bome deur mikorisa-swamme aan mekaar verbind kan word en koolstof tussen hulle deurlaat. So ek het dit tussen berk en denne in my siek plantasies getoets.

Ek het berk en denne en sederhout saam in klein drieling geplant. . En ek het opgespoor hoe daardie koolstofmolekules heen en weer tussen die berk en spar gegaan het en hulle het nie eintlik in die seders beland nie. Omdat die seders, hulle vorm 'n ander soort mikorisa-swam wat nie met berk of spar assosieer nie. So [die seder] was nie eintlik in die netwerk met berk en spar nie, en dit het amper niks van hierdie isotoop opgetel nie.

Ek het geweet dat berk en spar koolstof onder die grond deel - veels teen die heersende wysheid dat hulle net om lig meeding en ook dat hoe meer die berk die Douglasspar bedek, hoe meer koolstof na Douglasspar gestuur is. Daar was dus 'n netto oordrag van berk na spar wat die skadu-effek daarvan versag het.

Op hierdie manier het die ekosisteem sy balans behou - die berk en spar kon saambestaan ​​as gevolg van hierdie samewerkende gedrag wat soort van die kompetisie wat aan die gang was, verreken.

Oor die maniere waarop haar eie borskankerdiagnose haar navorsing gevorm het

Dit het beslis 'n groot invloed op my gehad, en my lewe het as gevolg daarvan verander, maar dit het ook my navorsing verander. Dit was toe dat ek met familie-herkenning begin werk het, om te sien of hierdie ou bome, veral toe hulle besig was om te sterf, hul familie kon herken en help. En ek het gegradueerdes laat kom om eintlik daardie vrae te vra. Jy weet, as 'n boom besig is om te sterf, stuur hulle meer [voedingstowwe en ander seine] na hul familielede? En ons het gevind dat hulle dit doen.

Toe het ek ook met navorsing begin - een van die belangrikste chemoterapie-medisyne wat aan my toegedien is, was paclitaxel [ook genoem Taxol]. Paclitaxel is 'n verdedigingsmiddel - eintlik 'n verdedigingschemikalie - wat geproduseer word deur die Stille Oseaan taxusboom, of eintlik alle taxus regoor die wêreld. Dit was noodsaaklik vir my herstel - hierdie verbinding wat bome produseer om hulself teen siektes te verdedig.

En daarom het ek gedink, weet jy wat, ek wil meer hieroor uitvind. Ek het 'n studie met 'n nuwe gegradueerde student, Eva, begin en sy kyk na die omgewing van taxus – of hulle met ou seders en esdoorns geassosieer word, en hoe hul bure hul vermoë kan beïnvloed om hoëgehalte Taxol te produseer om hul verdediging.

Ons het pas uitgevind dat hierdie bome almal met mekaar verbind is deur hierdie gespierde mikorisale netwerk, wat die weë bied vir hulle om hierdie inligting te kommunikeer. So, ja, ons begin met daardie werk. Ek is hoopvol dat dit ons sal help om, vir een ding, hierdie bome te bewaar vir hul medisinale eienskappe - want hulle is vernuftig in wat hulle gedoen het. Hulle het hierdie, wat ons medisyne noem, ontwikkel, maar hulle is ook vir hulself om hulself teen siekte te verdedig. Die kankerbehandeling is wat my gedryf het om hierdie studie te doen. En ek is so opgewonde om uit te vind wat ons leer.

Oor hoekom dit belangrik is om 'n ou boom op sy eie deur die lang doodsproses te laat gaan

[Bome] word oud. Hulle neem uiteindelik af. En doodgaan is 'n proses, en dit neem 'n lang, lang tyd. Dit kan dekades neem vir 'n boom om dood te gaan. In die proses om te sterf, is daar baie dinge wat aangaan. En een van die dinge wat ek bestudeer het, was waarheen gaan hul energie - waar gaan die koolstof wat in hul weefsels gestoor word - waarheen gaan dit? En so benoem ons sommige bome met koolstofdioksied - met C13, wat 'n stabiele isotoop is - en ons het gekyk hoe ons hierdie bome eintlik laat doodgaan. Ons stres hulle uit deur hul naalde af te trek en hulle aan te val met knopwurms ensovoorts. En toe kyk ons ​​wat met hul koolstof gebeur het.

En ons het gevind dat ongeveer 40% van die koolstof deur netwerke na hul naburige bome oorgedra is. Die res van die koolstof sou net deur natuurlike ontbindingsprosesse versprei het. maar sommige daarvan word reg in die bure gerig. En op hierdie manier het hierdie ou bome eintlik 'n baie direkte uitwerking op die herlewingsvermoë van die nuwe woud vorentoe.

Dit is 'n heeltemal ander manier om te verstaan ​​hoe ou bome bydra tot die volgende generasies - dat hulle agentskap in die volgende generasies het. En ons praktyke van berging om ontslae te raak van sterwende bome, of bome wat pas dood is of in veldbrande verbrand is - as ons ingaan en dit dadelik sny, kortsluit ons eintlik daardie natuurlike proses.

Ons studies dui daarop dat dit 'n impak op die wedergeboorte sal hê. Hulle gaan nie so goed voorbereid wees vir hul lewens wat vorentoe kom nie. So ek het probeer om vir mense te sê: Kom ons hou terug met hierdie berging totdat bome die kans gehad het om hierdie energie en inligting oor te dra aan die nuwe saailinge wat opkom.

Sam Briger en Thea Chaloner het hierdie onderhoud vir uitsending vervaardig en geredigeer. Bridget Bentz, Molly Seavy-Nesper en Deborah Franklin het dit vir die web aangepas.


Hoe kan die swamnetwerk woude gesond hou?

Bome maak staat op hul swamnetwerk om te kommunikeer en kennis op te doen net soveel as wat ons mense op die internet staatmaak! 'n Gesonde woud is een wat goed verbind is deur die "internet van bome" en het baie moederbome. Dit laat 'n woud toe om te herstel van ewekansige veranderinge, soos dié wat veroorsaak word deur mense wat bome oes.

Wetenskaplikes kan gebruik wat hulle oor die "houtwye web" geleer het om houtkappers te help om beter besluite te neem wanneer hulle bome oes. Byvoorbeeld, om redes waarvan jy gelees het, moet houtkappers moederbome in die woud aan die lewe hou. En hulle moet sterwende bome toelaat om hul voedingstowwe vry te stel voordat hulle dit verwyder.

Next time you stroll through the woods, think of all the communication happening just beneath your feet!


24.1 Characteristics of Fungi

Aan die einde van hierdie afdeling sal jy die volgende kan doen:

  • List the characteristics of fungi
  • Describe the composition of the mycelium
  • Describe the mode of nutrition of fungi
  • Explain sexual and asexual reproduction in fungi

Swamme, wat eens as plantagtige organismes beskou is, is nouer verwant aan diere as plante. Swamme is nie in staat tot fotosintese nie: hulle is heterotrofies omdat hulle komplekse organiese verbindings as energiebronne en koolstof gebruik. Fungi share a few other traits with animals. Their cell walls are composed of chitin, which is found in the exoskeletons of arthropods. Fungi produce a number of pigments, including melanin, also found in the hair and skin of animals. Like animals, fungi also store carbohydrates as glycogen. However, like bacteria, fungi absorb nutrients across the cell surface and act as decomposers, helping to recycle nutrients by breaking down organic materials to simple molecules.

Sommige swamorganismes vermeerder slegs aseksueel, terwyl ander beide ongeslagtelike voortplanting en seksuele voortplanting ondergaan met afwisseling van geslagte. Most fungi produce a large number of spores , which are haploid cells that can undergo mitosis to form multicellular, haploid individuals.

Swamme werk dikwels met ander organismes en vorm voordelige of mutualistiese assosiasies. For example, most terrestrial plants form symbiotic relationships with fungi. The roots of the plant connect with the underground parts of the fungus, which form mycorrhizae . Through mycorrhizae, the fungus and plant exchange nutrients and water, greatly aiding the survival of both species. Alternatively, lichens are an association between a fungus and its photosynthetic partner (usually an alga).

Swamme veroorsaak ook ernstige infeksies by plante en diere. Byvoorbeeld, Hollandse iepsiekte, wat deur die swam veroorsaak word Ophiostoma ulmi, is 'n besonder verwoestende tipe swambesmetting wat baie inheemse spesies iep vernietig (Ulmus sp.) deur die boom se bloedvatstelsel te besmet. Die elmbaskewer dien as 'n vektor, wat die siekte van boom tot boom oordra. Die swam, wat per ongeluk in die 1900's bekendgestel is, het elmbome regoor die vasteland vernietig. Baie Europese en Asiatiese elms is minder vatbaar vir Nederlandse elmsiekte as Amerikaanse elms.

By mense word swaminfeksies oor die algemeen as uitdagend beskou om te behandel. Anders as bakterieë, reageer swamme nie op tradisionele antibiotika-terapie nie, aangesien hulle eukariote is. Swaminfeksies kan dodelik wees vir individue met gekompromitteerde immuunstelsels.

Swamme het baie kommersiële toepassings. Die voedselbedryf gebruik giste in bak, brou en kaas- en wynmaak. Baie industriële verbindings is neweprodukte van swamfermentasie. Swamme is die bron van baie kommersiële ensieme en antibiotika.

Although humans have used yeasts and mushrooms since prehistoric times, until recently, the biology of fungi was poorly understood. In fact, up until the mid-20th century, many scientists classified fungi as plants! Fungi, like plants, are mostly sessile and seemingly rooted in place. They possess a stem-like structure similar to plants, as well as having a root-like fungal mycelium in the soil. In addition, their mode of nutrition was poorly understood. Progress in the field of fungal biology was the result of mycology : the scientific study of fungi. Based on fossil evidence, fungi have been found in the Denovian era, about 410 million years ago. However, new findings might place the appearance of the first fungi during the Neoproterozoic era, about 900 million years ago. Molecular biology analysis of the fungal genome demonstrates that fungi are more closely related to animals than plants. Under some current systematic phylogenies, they continue to be a monophyletic group of organisms.

Loopbaanverbinding

Mycologist

Mycologists are biologists who study fungi. Historically, mycology was a branch of microbiology, and many mycologists start their careers with a degree in microbiology. To become a mycologist, a bachelor's degree in a biological science (preferably majoring in microbiology) and a master's degree in mycology are minimally necessary. Mycologists can specialize in taxonomy and fungal genomics, molecular and cellular biology, plant pathology, biotechnology, or biochemistry. Some medical microbiologists concentrate on the study of infectious diseases caused by fungi, called mycoses. Mycologists collaborate with zoologists and plant pathologists to identify and control difficult fungal infections, such as the devastating chestnut blight, the mysterious decline in frog populations in many areas of the world, or the deadly epidemic called white nose syndrome, which is decimating bats in the Eastern United States.

Government agencies hire mycologists as research scientists and technicians to monitor the health of crops, national parks, and national forests. Mycologists are also employed in the private sector by companies that develop chemical and biological control products or new agricultural products, and by companies that provide disease control services. Because of the key role played by fungi in the fermentation of alcohol and the preparation of many important foods, scientists with a good understanding of fungal physiology routinely work in the food technology industry. Oenology, the science of wine making, relies not only on the knowledge of grape varietals and soil composition, but also on a solid understanding of the characteristics of the wild yeasts that thrive in different wine-making regions. It is possible to purchase yeast strains isolated from specific grape-growing regions. The great French chemist and microbiologist, Louis Pasteur, made many of his essential discoveries working on the humble brewer’s yeast, thus discovering the process of fermentasie.

Cell Structure and Function

Fungi are eukaryotes, and as such, have a complex cellular organization. As eukaryotes, fungal cells contain a membrane-bound nucleus. The DNA in the nucleus is represented by multiple linear molecules wrapped around histone proteins, as is observed in other eukaryotic cells. A few types of fungi have accessory genomic structures comparable to bacterial plasmids (loops of DNA) however, the horizontal transfer of genetic information that occurs between one bacterium and another rarely occurs in fungi. Fungal cells also contain mitochondria and a complex system of internal membranes, including the endoplasmic reticulum and Golgi apparatus.

Unlike plant cells, fungal cells do not have chloroplasts or chlorophyll. Many fungi display bright colors arising from other cellular pigments, ranging from red to green to black. The poisonous Amanita muscaria (fly agaric) is recognizable by its bright red cap with white patches (Figure 24.2). Pigments in fungi are associated with the cell wall and play a protective role against ultraviolet radiation. Some fungal pigments are toxic to humans.

Like plant cells, fungal cells have a thick cell wall. The rigid layers of fungal cell walls contain complex polysaccharides called chitien en glucans. Chitin (N-acetyl-D-glucosamine), also found in the exoskeleton of arthropods such as insects, gives structural strength to the cell walls of fungi. The wall provides structural support and protects the cell from desiccation and some predators. Fungi have plasma membranes similar to those of other eukaryotes, except that the structure is stabilized by ergosterol: a steroid molecule that replaces the cholesterol found in animal cell membranes. Most members of the kingdom Fungi are nonmotile. However, flagella are produced by the spores and gametes in the primitive Phylum Chytridiomycota.

Groei

The vegetative body of a fungus is a unicellular or multicellular thallus. Unicellular fungi are called yeasts. Multicellular fungi produce threadlike hifes (singular hypha). Dimorphic fungi can change from the unicellular to multicellular state depending on environmental conditions. Saccharomyces cerevisiae (baker’s yeast) and Candida species (the agents of thrush, a common fungal infection) are examples of unicellular fungi (Figure 24.3).

Most fungi are multicellular organisms. They display two distinct morphological stages: the vegetative and reproductive. The vegetative stage consists of a tangle of hyphae, whereas the reproductive stage can be more conspicuous. The mass of hyphae is a mycelium (Figure 24.4). It can grow on a surface, in soil or decaying material, in a liquid, or even on living tissue. Although individual hyphae must be observed under a microscope, the mycelium of a fungus can be very large, with some species truly being “the fungus humongous.” The giant Armillaria solidipes (honey mushroom) is considered the largest organism on Earth, spreading across more than 2,000 acres of underground soil in eastern Oregon it is estimated to be at least 2,400 years old.

Most fungal hyphae are divided into separate cells by endwalls called septa (singular, septum ) (Figure 24.5a, c). In most phyla of fungi, tiny holes in the septa allow for the rapid flow of nutrients and small molecules from cell to cell along the hypha. They are described as perforated septa. The hyphae in bread molds (which belong to the Phylum Zygomycota) are not separated by septa. Instead, they are formed by large cells containing many nuclei (multinucleate), an arrangement described as coenocytic hyphae (Figure 24.5b).

Fungi thrive in environments that are moist and slightly acidic, and can grow in dark places or places exposed to light. They vary in their oxygen requirement. Most fungi are obligate aerobes , requiring oxygen to survive. Other species, such as members of the Chytridiomycota that reside in the rumen of cattle, are obligate anaerobes , in that they only use anaerobic respiration because oxygen will disrupt their metabolism or kill them. Yeasts are intermediate, being facultative anaerobes . This means that they grow best in the presence of oxygen using aerobic respiration, but can survive using anaerobic respiration when oxygen is not available. The alcohol produced from yeast fermentation is used in wine and beer production.

Voeding

Like animals, fungi are heterotrophs they use complex organic compounds as a source of carbon, rather than fix carbon dioxide from the atmosphere as do some bacteria and most plants. In addition, fungi do not fix nitrogen from the atmosphere. Like animals, they must obtain it from their diet. However, unlike most animals, which ingest food and then digest it internally in specialized organs, fungi perform these steps in the reverse order digestion precedes ingestion. Eerstens, exoenzymes are transported out of the hyphae, where they process nutrients in the environment. Then, the smaller molecules produced by this external digestion are absorbed through the large surface area of the mycelium. As with animal cells, the polysaccharide of storage is glikogeen, a branched polysaccaride, rather than amylopectin, a less densely branched polysaccharide, and amylose, a linear polysaccharide, as found in plants.

Fungi are mostly saprobes (saprophyte is an equivalent term): organisms that derive nutrients from decaying organic matter. They obtain their nutrients from dead or decomposing organic material derived mainly from plants. Fungal exoenzymes are able to break down insoluble compounds, such as the cellulose and lignin of dead wood, into readily absorbable glucose molecules. The carbon, nitrogen, and other elements are thus released into the environment. Because of their varied metabolic pathways, fungi fulfill an important ecological role and are being investigated as potential tools in bioremediasie of chemically damaged ecosystems. For example, some species of fungi can be used to break down diesel oil and polycyclic aromatic hydrocarbons (PAHs). Other species take up heavy metals, such as cadmium and lead.

Some fungi are parasitic, infecting either plants or animals. Smut and Dutch elm disease affect plants, whereas athlete’s foot and candidiasis (thrush) are medically important fungal infections in humans. In environments poor in nitrogen, some fungi resort to predation of nematodes (small non-segmented roundworms). In fact, species of Arthrobotrys fungi have a number of mechanisms to trap nematodes: One mechanism involves constricting rings within the network of hyphae. The rings swell when they touch the nematode, gripping it in a tight hold. The fungus then penetrates the tissue of the worm by extending specialized hyphae called haustoria . Many parasitic fungi possess haustoria, as these structures penetrate the tissues of the host, release digestive enzymes within the host's body, and absorb the digested nutrients.

Reproduksie

Fungi reproduce sexually and/or asexually. Some fungi reproduce both sexually and asexually, while other fungi reproduce only asexually (by mitosis).

In both sexual and asexual reproduction, fungi produce spores that disperse from the parent organism by either floating on the wind or hitching a ride on an animal. Fungal spores are smaller and lighter than plant seeds. For example, the giant puffball mushroom bursts open and releases trillions of spores in a massive cloud of what looks like finely particulate dust. The huge number of spores released increases the likelihood of landing in an environment that will support growth (Figure 24.6).

Aseksuele voortplanting

Fungi reproduce asexually by fragmentation, budding, of producing spores. Fragmente van hifes kan nuwe kolonies laat groei. Somatic cells in yeast form buds. During budding (an expanded type of cytokinesis), a bulge forms on the side of the cell, the nucleus divides mitotically, and the bud ultimately detaches itself from the mother cell (Figure 24.7).

The most common mode of asexual reproduction is through the formation of asexual spores, which are produced by a single individual thallus (through mitosis) and are genetically identical to the parent thallus (Figure 24.8). Spores allow fungi to expand their distribution and colonize new environments. They may be released from the parent thallus either outside or within a special reproductive sac called a sporangium .

There are many types of asexual spores. Conidiospores are unicellular or multicellular spores that are released directly from the tip or side of the hypha. Other asexual spores originate in the fragmentation of a hypha to form single cells that are released as spores some of these have a thick wall surrounding the fragment. Yet others bud off the vegetative parent cell. In contrast to conidiospores, sporangiospores are produced directly from a sporangium (Figure 24.9).

Seksuele voortplanting

Sexual reproduction introduces genetic variation into a population of fungi. In fungi, seksuele voortplanting often occurs in response to adverse environmental conditions. During sexual reproduction, two mating types are produced. When both mating types are present in the same mycelium, it is called homothallic , or self-fertile. Heterothallic mycelia require two different, but compatible, mycelia to reproduce sexually.

Although there are many variations in fungal sexual reproduction, all include the following three stages (Figure 24.8). First, during plasmogamy (literally, “marriage or union of cytoplasm”), two haploid cells fuse, leading to a dikaryotic stage where two haploid nuclei coexist in a single cell. During karyogamy (“nuclear marriage”), the haploid nuclei fuse to form a diploid zygote nucleus. Finally, meiosis takes place in the gametangia (singular, gametangium) organs, in which gametes of different mating types are generated. At this stage, spores are disseminated into the environment.

Skakel na Leer

Review the characteristics of fungi by visiting this interactive site from Wisconsin-online.


Christopher Fernandez is a postdoctoral associate in Plant and Microbial Biology at the University of Minnesota in Minneapolis, Minnesota.

IRA FLATOW: Dit is Wetenskap Vrydag. Ek’m Ira Flatow. One of the most extensive networks for sharing information and moving around essential goods is hidden from us. Yeah, it’s right below our feet. You might have heard of it. It’s the wood wide web. See what I did there? I’m talking about the fungal networks that connect trees and plants to one another. Scientists are starting to untangle what these fungal connections look like and how fungi respond and are affected by climate change, and what that means for the entire forest ecosystem.

This is something I really want to talk about with my next guest. He’s here to walk us through this mycological maze. Christopher Fernandez is a post-doctoral associate in plant and microbial biology University of Minnesota in Minneapolis. They call it the U over there, right, Chris?

CHRISTOPHER FERNANDEZ: That’s right.

IRA FLATOW: Welcome to Science Friday.

CHRISTOPHER FERNANDEZ: Thanks for having me, Ira.

IRA FLATOW: Even though we can’t see it, fungi play an important role, right? When it comes to trees and plant ecosystems. Can you take us through a bit of fungi 101? What do fungi fungi provide for plants.

CHRISTOPHER FERNANDEZ: Absolutely, yeah. So the organisms that I study are called mycorrhizal fungi. So these are fungi that are really important for the plant nutrition. Basically, these fungi colonize the finest roots of plants and provide access to nutrients that would otherwise be unavailable for direct plant uptake. So plant root activity is directly dependent on these kinds of associations.

And so about 90%– we’re saying these days– of plant species actually has one of these types of mycorrhizal associations. So there are two basic types of mycorrhizal associations are arbuscular mycorrhizal fungi, which are really common in grassland-type ecosystems and prairies and tropical forests. And then, there are ectomycorrhizal fungi, which are really important in temperate and boreal forests. And those are the organisms that I work with.

IRA FLATOW: Which ones do we see on our lawns and in the backyards on trees?

CHRISTOPHER FERNANDEZ: Yeah, so it would depend. If it’s a mushroom forming fungus, then it is a ectomycorrhizal fungus. Or it could be a saccharo cerevic fungus that just is decaying soil organic matter.

IRA FLATOW: There are also free living fungi?

CHRISTOPHER FERNANDEZ: Yeah, and they depend on carbon and nitrogen and phosphorus that exists in soil organic matter. And they break down that soil organic matter to obtain those resources. Whereas, mycorrhizal fungi, they acquire nitrogen and phosphorus and trade that– those nutrients to the plant in exchange for carbon.

IRA FLATOW: Is it true that the largest organism in the world is a fungus?

CHRISTOPHER FERNANDEZ: That is true, yeah. That would be an Armillaria species out West– in Oregon, I believe. Ja. And that is supposedly very, very large– acres.

IRA FLATOW: Which fungi are populating my sourdough bread?

CHRISTOPHER FERNANDEZ: Those would be yeast, primarily. So those are free living single-celled fungi.

IRA FLATOW: How many different fungal species does the average tree have, let’s say, associated with it?

CHRISTOPHER FERNANDEZ: In the systems that I work in, which are temperate and boreal forest, trees can have dozens of different fungal species colonizing their root system. It’s quite common to see 50, 60 different fungal species colonizing a single tree host.

IRA FLATOW: Wow. Fungi like the microbiome of the forest, it sounds like.

CHRISTOPHER FERNANDEZ: Yeah, absolutely. Just like you and I have our own microbiomes associated with our bodies, these trees have their own associated microbes including mycorrhizal fungi as well as some other bacteria and other things.

IRA FLATOW: So you’re saying that different types of forests have different types of fungal networks there.

CHRISTOPHER FERNANDEZ: Depending on which systems you’re looking at, they have completely different sets of fungal associates. Ja.

IRA FLATOW: So if you planted a tropical tree in a conifer forest would it be able to tap in and use these different fungi in the soil?

CHRISTOPHER FERNANDEZ: Probably not. So most tropical trees– not all, but most tropical trees are arbuscular mycorrhizal associates. So they tend to form these mycorrhizal associations with a different set of symbiote. So these are quite different in terms of their functionality as well as their phylogeny. So they’re very different.

IRA FLATOW: Ek het dit nie geweet nie. So if I dig up the soil in my backyard, am I disturbing a ecosystem that’s taken decades, centuries to form?

CHRISTOPHER FERNANDEZ: Probably not. So where we dwell, usually, those soils are pretty disturbed anyway. Unless you’re living in a forest system, you’re probably not causing any more disturbance to those soils or anything that would be traumatic.

IRA FLATOW: Like with most things, climate change is affecting these fungal communities, correct? What changes are you and other scientists observing here?

CHRISTOPHER FERNANDEZ: So here in Minnesota, we have a system– an experiment set up by Dr. Peter Reich in 2008 It was also at the University of Minnesota. It’s called Be Forewarmed. And basically, the experiment is warming and excluding precipitation in these forest plots that have different boreal and temperate hosts planted together. And there’s been a lot of research on aboveground responses to climate change– these climate change treatments.

And we are interested in understanding how those changes cascade below ground and influence communities. And what we’re finding is that the networks that are formed between these different plant hosts are starting to degrade. So the communities are shifting from those that have– just species that have extensive, long-lived mycelium in the soil, to those that are weedy. They don’t produce a lot of mycelium. They shift a lot of resources to reproduction rather than exploration in these structures.

Basically, we’re hypothesizing that this is going to result in the breakdown of these really important networks.

IRA FLATOW: This doesn’t sound good.

CHRISTOPHER FERNANDEZ: No. No, it does not. These networks are quite important for plant nutrition, right? So we think that this will ultimately affect seedling recruitment. So seedlings are really dependent on the established common mycorrhizal networks, we call them, for being connected and tapped into an established network and having access to nutrients provided by those networks.

And so we think that this might alter how seedlings are recruited in the future.

IRA FLATOW: So the trees– the population of trees may go down because the fungus is doing something different than it used to.

CHRISTOPHER FERNANDEZ: Right, exactly. Instead of providing these really important benefits in terms of nutrition, maybe those won’t be there in the future.

IRA FLATOW: There is research out there that some fungi play a role in drought tolerance in trees. How does that happen?

CHRISTOPHER FERNANDEZ: Yeah, so there’s a lot of interesting work coming out of Cathering Gehring’s lab down at Northern Arizona University showing that some of these ectomycorrhizal symbiotes that have evolved in these really droughty environments have abilities to basically help the plant tolerate increased drought stress. Those are very different fungi than some of the fungi that you see here in Minnesota or higher latitude systems that have not evolved to tolerate those challenges with water stress. But they are out there.

IRA FLATOW: If you know that fungi– they’re beneficial or do better in the face of climate change, you know there are certain fungi that do better. Can you give a tree a fungal probiotic– an inoculation, so to speak, to help it out?

CHRISTOPHER FERNANDEZ: That’s certainly a strategy that could be explored. Today, I don’t think there’s a whole lot of research that would suggest that can be done immediately. But that is something that can be explored for sure. Cenococcum, the species of fungi that I’m interested in, actually is known for its ability to tolerate drought stress. But it doesn’t really– it’s not really abundant in a lot of these communities.

And we don’t really see it go up in abundance with– when we increase warming and drought stress in our system here in Minnesota. So it gets complicated.

IRA FLATOW: I know that fungi are also important in carbon sequestration. How will climate change affect this?

CHRISTOPHER FERNANDEZ: 20% to 30% of net primary productivity, that is the amount of carbon that plants pull down from the atmosphere and fix into biomass, is allocated below ground to mycorrhizal fungi. So that’s a significant flux into the soil. So the turnover of that mycorrhizal biomass that is produced from carbon allocation from this plant is important in terms of potential for carbon sequestration.

So what we’re seeing is that with warming and a drought, at least here in our system, the photosynthetic capacity of these hosts are declining significantly. And we think that their ability to allocate carbon below ground to mycorrhizal fungi is also being inhibited. It’s kind of like a sinking ship, right? So the fungi are attached to these hosts and are dependent on that carbon. And those fungi are really– thought to be really important in terms of the ability to sequester carbon in soil. So it’s quite troubling.

IRA FLATOW: Will fungal species that are better adapted to higher temperatures, are we going to see them start to dominate the forests under climate change and determine which trees grow in an area?

CHRISTOPHER FERNANDEZ: Yeah, so perhaps. Yeah, we’re seeing not so much drought tolerant species but drought avoiders. So these are weedy fungi, again, that invest a lot in reproduction rather than biomass in the soil. So instead of producing biomass they can tolerate droughty or warmer soils, they’re just avoiding those times of the year, right? And they’re growing when there is moisture available and reproducing really quickly. And then, just kind of dying off.

IRA FLATOW: I know we’ve already certified you as a fungi geek. And there’s probably nothing you don’t know about fungi. But what are the big questions? What more do you want to know about fungi and the role they play in these forest ecosystems?

CHRISTOPHER FERNANDEZ: We’re just scratching the surface on what we know about these fungi. We just have the ability for about 10 years to actually observe these fungi in situ with high throughput sequencing. So for the longest time, we couldn’t actually study them very effectively.

So we’re just now beginning to piece together patterns from these data sets. So what I’m particularly interested in is understanding functional diversity. So what are the traits that these different fungi have? What is their effect on their performance in ecosystems? So are there traits that confer tolerance to certain stressors? What are the traits that are really important for accessing nutrients?

And how did those traits, then, affect these ecosystem level processes? So basically, we’re just now being able to actually observe these things in the environment.

IRA FLATOW: Well, we’ve run out of time. It’s been quite informative. I want to thank you, Christopher Fernandez, postdoctoral associate in plant and microbial biology University of Minnesota in Minneapolis. Thank you for telling us all about the fungus among us.


Simbiose

‘Symbiosis’ comes from Greek, and means ‘living together’. In its technical sense, ecologists use the word to talk about a range of interactions:

    is where one organism feeds on another, without necessarily killing the host.
  • Commensalism is when one organism harmlessly ‘hitches a ride’ on another.
  • Mutualism refers to those interactions in which both organisms benefit. In popular usage, when we talk about symbiosis we usually mean mutualistic relationships. Let’s explore these win-win partnerships and the vital role they play in the forest.
Lichens

Lichens rest near the foundations of many ecosystems. These amazing organisms are actually made up of a fungus and an alga. Sometimes a third player called a cyanobacteria is also involved. The fungus forms the structure of the lichen, while the alga provides the energy through photosynthesis. This is a very close alliance called endosymbiosis. It means one organism lives inside the cells or body of another.

There are many species of lichen within the Caledonian forest. Among the more common ones are map lichen – a crust-like species that grows on rocks. Amazingly, it secretes acids which can dissolve rock. This helps to start the process of soil formation. Lichens can form a substrate on which other plants can grow. They are often habitat for tiny mites, spiders and other invertebrates.

Mycorrhizas

Fungi are another crucial, but often under-appreciated part of forest ecosystems. Mycorrhizas are symbiotic relationships between certain fungi and the roots of plants. The fine fungal threads (called hyphae) wrap around or penetrate the host plant’s roots. The fungus helps the plant to extract nutrients and water from the soil. It also protects its host against harmful organisms. In return the fungus receives sugars via the plant’s photosynthesis.

As with most mutualistic relationships, each partner grows better with the other than it would alone. Birch has a number of these partnerships, the most familiar being with the red-with-white-spots fly agaric. The sought-after chanterelle is also partner of birch. Scots pine has mycorrhizal associations with over 200 species of fungi in Scotland. In fact, the majority of plants in the Caledonian forest benefit from mycorrhizal relationships. Mycorrhizas helped plants to colonise the land, millions of years ago.

Symbiosis and cells

Indeed, many scientists believe that most major evolutionary leaps were ‘jump-started’ by symbiosis. Plant and animal cells contain organelles. These are structures that perform special functions within the cell. They evolved from endosymbiotic relationships, with one bacterium living inside another cell. A key organelle within plant cells is the chloroplast, which is responsible for photosynthesis. Chloroplasts evolved from cyanobacteria – primitive bacteria that can themselves photosynthesise. Looking around at the tapestry of green, we can really see the scale on which symbiosis has influenced the forest.

Symbiotic bacteria

Symbiosis works on many different scales. For example there is a relationship between alder and a bacterium called Frankia alni. In this case, Frankia lives inside nodules on alder roots. The bacteria absorb nitrogen from the atmosphere and fix it in the soil. This benefits the alder, which via photosynthesis provides the bacteria with sugars. The soil becomes enriched as a result of this process. In fact people have used alder in various parts of the world, to restore depleted soils.

Ruminants are hoofed mammals that digest their food in two stages. Examples in the Caledonian forest include red deer and the now-extinct aurochs. Ruminants have a complex digestive system, and depend on symbiosis for their survival. After their food is regurgitated to be chewed as ‘cud’, it then enters one of four stomach chambers. Bacteria break down the otherwise indigestible cellulose in the plant material. The bacteria get glucose as part of the bargain. They produce volatile fatty acids, providing their host mammal with energy.

Bestuiwing

Pollination is a form of symbiosis that is easy to observe. Flowers act as powerful adverts to insects, offering energy-rich nectar. The insect, having fed upon the sugary liquid, then unknowingly carries pollen to fertilise other flowers. This benefits the overall population of that particular plant species.

Many insects are choosy about the plants they visit. Certain bee species have a longer ‘tongue’ than others, and this affects their choice of flower. The white-tailed bumblebee for example, chooses deeper flowers such as foxglove. The shorter-tongued bees can only drink nectar from flowers that are not as deep, such as goat willow.

Pollination probably evolved in response to early insects eating the pollen itself. Plants that offered nectar as an alternative to pollen would stand a better chance of reproducing. The pollen was not only spared, but carried from plant to plant. Insects could still feed, and flowering plants evolved and thrived.

Bessies

Berries evolved in a similar way, with the plant adapting to cope with animals feeding on its seeds. The bird or mammal gains a meal, while the plant’s seed is not only unharmed, but dispersed. The seeds of some plants (such as rowan) are often ‘activated’ by passing through the rigours of a digestive system.

The berries of many plants including rowan, holly and bird cherry, all take part in symbiotic relationships with birds. Some mammals such as the pine marten also feed on, and disperse, berries.

Wood ants

Wood ants have symbiotic relationships with a number of other organisms in the forest. Some species of flowering plant in the forest depend on ants for their dispersal. Cow-wheat seeds have a fatty attachment on them. The ants take the seeds to their nests, and feed the fatty bit to their larvae, thus helping to disperse the plant. In deforested areas, such plants cannot return easily without the aid of ants. This is important to know if we want to restore ground flora to areas of new woodland.

Wood ants have a fascinating partnership with certain aphids. The ants stroke the aphids, stimulating them to release a waste product known as honeydew. This liquid provides a meal for the ants, while the aphids benefit by gaining the ants’ protection from predators. The ants also protect the aphids’ food source from competing sapsuckers.

A worm called Dendrodrilus rubidus often lives in the nests of northern wood ants. Here the conditions are very suitable for worms, with an abundant food supply. The worms benefit the ants by helping prevent the mounds from becoming overgrown with moulds and fungi.

Wolves and ravens

There is a close relationship between ravens and wolves. Wolves not only make carcasses available, but also open up tough hides that the birds would not be able to penetrate by themselves. Wolves often howl before going on hunt and ravens have learned to respond to this cue. It may be that wolves have also learned to listen to raven calls indicating that there are deer about. Perhaps similar interactions took place in the Caledonian forest before humans wiped out wolves.

Mutually beneficial partnerships occur on many different levels and their influence is huge. Some of the most fundamental processes, from photosynthesis to the survival of herbivores, happen thanks to these alliances.


Twigs

The leaf scars on twigs are a characteristic shape for each species, the sealed vascular bundles, making a pattern of dots in them. Since each leaf usually has a bud in its axil, above each leaf scar there should be a lateral bud.

Earlier in the year, when the terminal bud was sprouting, the bud scales, unlike the foliage leaves, were not spaced out on the stem, and when they fell off they left narrow scars, close together, extending from a quarter to half-way round the stem. These are commonly called girdle scars and, since they mark the position of each year's terminal bud, the length of stem between each set of girdle scars represents one year's growth.

On many twigs there is a scattering of small dots. These are lenticels, gaps in the bark with areas of loosely packed cells, which provide pores through which the stem can exchange oxygen and carbon dioxide


Kyk die video: Gljive na Kopaoniku (September 2022).