Table Of ContentSoil Biology
9
Series Editor: Ajit Varma
Volumespublishedintheseries
Volume1
A.Singh,O.P.Ward(Eds.)
AppliedBioremediationandPhytoremediation
2004
Volume2
A.Singh,O.P.Ward(Eds.)
BiodegradationandBioremediation
2004
Volume3
F.Buscot,A.Varma(Eds.)
MicroorganismsinSoils:RolesinGenesisandFunctions
2005
Volume4
S.Declerck,D.-G.Strullu,J.A.Fortin(Eds.)
InVitroCultureofMycorrhizas
2005
Volume5
R.Margesin,F.Schinner(Eds.)
ManualforSoilAnalysis–
MonitoringandAssessingSoilBioremediation
2005
Volume6
H.König,A.Varma(Eds.)
IntestinalMicroorganismsofTermites
andOtherInvertebrates
2006
Volume7
K.G.Mukerji,C.Manoharachary,J.Singh(Eds.)
MicrobialActivityintheRhizosphere
2006
Volume8
P.Nannipieri,K.Smalla(Eds.)
NucleicAcidsandProteinsinSoil
2006
Barbara J.E. Schulz
Christine J.C. Boyle
Thomas N. Sieber (Eds.)
Microbial Root
Endophytes
With29Figures,4inColor
123
PDDr.BarbaraJ.E.Schulz Dr.ChristineJ.C.Boyle
TechnicalUniversityofBraunschweig Augustastraße32
InstituteofMicrobiology 02826Görlitz
Spielmannstraße7 Germany
38106Braunschweig e-mail:[email protected]
Germany
e-mail:[email protected]
Dr.ThomasN.Sieber
SwissFederalInstituteofTechnology
DepartmentofEnvironmentalSciences
InstituteofIntegrativeBiology
ForestPathologyandDendrology
8092Zürich
Switzerland
e-mail:[email protected]
LibraryofCongressControlNumber:2005938057
ISSN1613-3382
ISBN-103-540-33525-0SpringerBerlinHeidelbergNewYork
ISBN-13978-3-540-33525-2SpringerBerlinHeidelbergNewYork
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Preface
Healthy plant roots are not only colonized by mycorrhizal fungi and rhi-
zobial bacteria, but also by a myriad of other microorganisms, including
endophyticbacteriaandfungi.Comparativelylittleisknownaboutthese
endophytic microorganisms, which do not cause apparent disease, but
colonizeroottissuesinter-and/orintracellulary.Althoughtherehadbeen
previous research studying both bacterial and fungal endophytes, it was
inthemid-1980sthatnumerousinvestigatorsbeganstudyingthesegroups
of microorganisms more intensively. Initially, most work on endophytes
centered on the diversity of isolates and correlations with ecological fac-
tors. Recently it has become clear that some of these interactions with
endophyticbacteriaandfungicanbelatentlypathogenicand/ormutualis-
tic.Inmutualisticinteractions,theendophytemayimprovegrowthofthe
host,conveystresstolerance,inducesystemicresistance,orsupplythehost
withnutrients.Ontheotherhand,mostendophytesarealsoabletogrow
saprotrophically,e.g.,fromsurface-sterilizedtissuesonmediacontaining
deadorganicsubstrates.Thus,ithasbecomeobviousthatendophyteshave
multiple life history strategies and that these can be extremely plastic, as
willbecomecleartothereadersofthesubsequent19chapters.
Thisbookisthefirsttodealwithbacterialandfungalrootendophytes,
theirdiversity,lifehistorystrategies,interactions,applicationsinagricul-
tureandforestry,andalsowithmethodsforisolation,cultivation,andboth
conventionalandmolecularmethodsforidentificationanddetection.The
first chapter deals with the question: What are endophytes? However, it
alsointroducesthereadertothesubjectstreatedinthesubsequentchap-
ters. We hope that readers will not only find this book informative, but
will also be provoked to further study these fascinating interactions, and
inparticulartobetterunderstandthemechanismsregulatingthem.Itwill
becomeapparentthatwearestillfarfromunderstandingthefactorsthat
determine whether a plant-microbial interaction remains asymptomatic,
leadstodisease,orismutualistic.
VI Preface
Wewouldliketothankourcolleaguesfortheircontributionsandtheir
worktomakethisbookasuccessfulunity,toJuttaLindenbornofSpringer
forherfriendlyhelpandadvice,andtoAjitVarmafortheinvitationtoedit
abookinthisseries.
Braunschweig, BarbaraSchulz
GörlitzandZürich, ChristineBoyle
June2006 andThomasSieber
Contents
1 WhatareEndophytes? 1
BarbaraSchulz,ChristineBoyle
1.1 IntroductionandDefinitions............................................ 1
1.2 Colonisation.................................................................. 2
1.3 AssemblagesandAdaptation............................................ 4
1.4 LifeHistoryStrategies ..................................................... 6
1.5 BalancedAntagonism...................................................... 7
1.6 Conclusions................................................................... 9
References............................................................................. 10
Part I Endophytic Bacteria
2 SpectrumandPopulationDynamics
ofBacterialRootEndophytes 15
JohannesHallmann,GabrieleBerg
2.1 Introduction.................................................................. 15
2.2 PopulationDensity ......................................................... 15
2.3 BacterialSpectrum ......................................................... 16
2.4 BacterialDiversity.......................................................... 21
2.5 FactorsInfluencingColonisation....................................... 21
2.5.1 Methodology....................................................... 21
2.5.2 Geography .......................................................... 22
2.5.3 PlantSpecies ....................................................... 22
2.5.4 PlantGenotype.................................................... 23
2.6 Interactions................................................................... 24
2.6.1 PlantPathogens................................................... 24
2.6.2 PlantSymbionts................................................... 25
2.6.3 PlantDefenceMechanisms.................................... 25
2.6.4 AgriculturalPractices........................................... 25
2.7 PotentialHumanPathogensAmongRootEndophytes.......... 26
2.8 Conclusions................................................................... 27
References............................................................................. 28
VIII Contents
3 BacterialEndophytesasElicitorsofInducedSystemicResistance 33
JosephW.Kloepper,Choong-MinRyu
3.1 IntroductionandTerminology ......................................... 33
3.2 ScopeofEndophytesthatElicitInducedResistance
andPathosystemsAffected............................................... 34
3.3 InternalColonizationofEndophytes
thatElicitInducedResistance........................................... 39
3.4 PlantResponsestoEndophyticElicitors............................. 41
3.5 ImplementationinProductionAgriculture:
TwoCaseStudies............................................................ 44
3.6 Conclusions................................................................... 49
References............................................................................. 50
4 ControlofPlantPathogenicFungiwithBacterialEndophytes 53
GabrieleBerg,JohannesHallmann
4.1 Introduction.................................................................. 53
4.2 SpectrumofIndigenousEndophyticBacteria
withAntagonisticPotentialTowardsFungalPlantPathogens 54
4.3 ModeofActionofAntagonisticBacteria............................ 58
4.3.1 Antibiosis ........................................................... 58
4.3.2 Competition........................................................ 59
4.3.3 Lysis................................................................... 59
4.3.4 InductionofPlantDefenceMechanisms.................. 60
4.3.5 PlantGrowth....................................................... 60
4.4 ControlPotentialofEndophyticBacteria............................ 60
4.5 EnhancingBiocontrolEfficiency....................................... 61
4.6 Conclusions................................................................... 65
References............................................................................. 66
5 RoleofProteinsSecretedbyRhizobiainSymbiotic
InteractionswithLeguminousRoots 71
MagedM.Saad,WilliamJ.Broughton,WilliamJ.Deakin
5.1 Introduction.................................................................. 71
5.2 BacterialProteinSecretionSystems................................... 73
5.2.1 TypeISecretionSystems....................................... 73
5.2.2 TypeIISecretionSystems...................................... 77
5.2.3 TypeIIISecretionSystems..................................... 77
5.2.4 TypeIVSecretionSystems..................................... 82
5.3 Conclusions................................................................... 83
References............................................................................. 83
Contents IX
6 ResearchonEndophyticBacteria:RecentAdvances
withForestTrees 89
RichaAnand,LesliePaul,ChrisChanway
6.1 Introduction.................................................................. 89
6.2 BacterialEndophytesofForestTrees.................................. 91
6.3 EndophyticBacteriaofConifers........................................ 92
6.4 ModesandSitesofEntry.................................................. 95
6.5 MechanismsofPlantGrowthPromotion............................ 97
6.6 FutureWork................................................................... 102
References............................................................................. 103
Part II Endophytic Fungi
7 BiodiversityofFungalRoot-EndophyteCommunities
andPopulations,inParticularoftheDarkSeptateEndophyte
Phialocephalafortiniis.l. 107
ThomasN.Sieber,ChristophR.Grünig
7.1 Introduction.................................................................. 107
7.2 SpeciesDiversityofRootEndophyteCommunities.............. 108
7.2.1 GeographyandClimate......................................... 109
7.2.2 Soil .................................................................... 114
7.2.3 MultitrophicInteractions ...................................... 115
7.2.4 NaturalandAnthropogenicDisturbances................ 117
7.3 DarkSeptateEndophytes................................................. 119
7.3.1 History............................................................... 119
7.3.2 Biodiversity......................................................... 119
7.3.3 DiversityofPhialocephalafortinii........................... 121
7.4 Conclusions................................................................... 125
References............................................................................. 126
8 EndophyticRootColonizationbyFusariumSpecies:
Histology,PlantInteractions,andToxicity 133
CharlesW.Bacon,IdaE.Yates
8.1 Introduction.................................................................. 133
8.2 PlantandFungusInteractions.......................................... 134
8.2.1 HemibiotrophicCharacteristics.............................. 138
8.2.2 Histology............................................................ 139
8.2.3 Mycotoxins.......................................................... 143
8.2.4 MycotoxinsandHostRelationships......................... 144
8.2.5 PhysiologicalInteractionsandDefenseMetabolites... 145
8.3 Summary....................................................................... 146
References............................................................................. 147
X Contents
9 MicrobialEndophytesofOrchidRoots 153
PaulBayman,J.TupacOtero
9.1 Introduction.................................................................. 153
9.2 HabitsandTypesofOrchidRoots ..................................... 153
9.3 BacteriaasEpiphytesandEndophytesofOrchidRoots ........ 154
9.4 OrchidEndophytesorOrchidMycorrhizalFungi?............... 155
9.5 ProblemswiththeTaxonomyofOrchidEndophyticFungi.... 157
9.6 HostSpecificityofOrchidEndophytes............................... 158
9.7 EndophyticFungiinRootsofTerrestrial,
PhotosyntheticOrchids................................................... 158
9.8 EndophyticFungiinRootsofMyco-HeterotrophicOrchids.. 167
9.9 EndophyticFungiinRootsofEpiphytic
andLithophyticOrchids.................................................. 169
9.10 EndophyticFungiinEpiphyticOrchidRoots:
ImportancetoPlantHosts................................................ 171
9.11 Conclusions................................................................... 172
References............................................................................. 173
10 FungalEndophytesinSubmergedRoots 179
FelixBärlocher
10.1 Introduction.................................................................. 179
10.2 AquaticHyphomycetes.................................................... 180
10.3 FungiinSubmergedRoots............................................... 181
10.4 ConclusionsandOutlook................................................. 186
References............................................................................. 188
11 NematophagousFungiasRootEndophytes 191
LuisV.Lopez-Llorca,Hans-BörjeJansson,JoséGasparMaciáVicente,
JesúsSalinas
11.1 Introduction.................................................................. 191
11.2 NematophagousFungi..................................................... 191
11.2.1 NematodeParasites.............................................. 192
11.2.2 Mycoparasites...................................................... 195
11.2.3 RootEndophytes.................................................. 195
11.3 ConcludingRemarks....................................................... 202
References............................................................................. 203
12 MolecularDiversityandEcologicalRolesofMycorrhiza-Associated
SterileFungalEndophytesinMediterraneanEcosystems 207
MariangelaGirlanda,SilviaPerotto,AnnaMariaLuppi
12.1 Introduction.................................................................. 207
