Soil Biology Asunción Morte Ajit Varma Editors Root Engineering Basic and Applied Concepts Soil Biology Volume 40 Series Editor AjitVarma,AmityInstituteofMicrobialTechnology, Amity University Uttar Pradesh, Noida, UP, India For furthervolumes: http://www.springer.com/series/5138 . Asuncio´n Morte (cid:129) Ajit Varma Editors Root Engineering Basic and Applied Concepts Editors Asuncio´nMorte AjitVarma FacultaddeBiolog´ıa AmityInstituteofMicrobialTechnology UniversidaddeMurcia AmityUniversityUttarPradesh Murcia Noida Spain UttarPradesh India ISSN1613-3382 ISSN2196-4831(electronic) ISBN978-3-642-54275-6 ISBN978-3-642-54276-3(eBook) DOI10.1007/978-3-642-54276-3 SpringerHeidelbergNewYorkDordrechtLondon LibraryofCongressControlNumber:2014936856 ©Springer-VerlagBerlinHeidelberg2014 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped.Exemptedfromthislegalreservationarebriefexcerpts inconnectionwithreviewsorscholarlyanalysisormaterialsuppliedspecificallyforthepurposeofbeing enteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthework.Duplication ofthispublicationorpartsthereofispermittedonlyundertheprovisionsoftheCopyrightLawofthe Publisher’s location, in its current version, and permission for use must always be obtained from Springer.PermissionsforusemaybeobtainedthroughRightsLinkattheCopyrightClearanceCenter. 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Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Foreword Rootsarehighlycomplexsystems.Theyareknowntoperformmostdiversetasks targetedatrootstructureandfunction.Inadditiontothemostobviousaspectssuch asstructuralsupportoftheplant,uptakeofwaterandnutrients,storageoffoodand nutrients,orvegetativereproduction,theyareinvolvedinphytohormonesynthesis and regulation of plant growth. Furthermore, roots interact with fungi, to form mycorrhizas, and bacteria in root nodules to mention only the most intensively studied symbioses. Root–microbial interactions are often related to effective defensemechanismsdirectedagainstphytopathogenicagents(Chap.17). All these achievements were acquired during evolution within the last 400millionyears,startingwiththeappearanceofthefirstlandplants.Considering thisenormousperiodoftime,itcanbeassumedthatpresent-dayrootsareoptimally adaptedtotheirnaturalenvironments. Nevertheless, there is growing interest in root engineering. In biology, root engineeringisunderstood—inanalogytogeneticengineering—asanalterationof rootstructureorfunctionbymeansofgeneticmodification,butalsobreedingand manipulatingrootsymbionts.Inthisway,itishopedtoadjustplantstoman-made stress situations and rapidly changing environments or to adapt them to totally artificialconditionsseeninrootculturestobeusedforpharmaceuticalpurposesand many other purposes, particularly in horticulture (Chap. 15). First attempts have been made with hairy root cultures transformed by Agrobacterium rhizogenes. Recent advances are reported in this book by the commercialization of hairy roots-based processes (Chap. 18). The identification of genetic markers for the selectionofimprovedadventitiousrootingperformancewillspeedupthistask.But anextensiontodifferenttypesofrootcultureiscominguponlyslowly. Thereasonforslowprogressinrootengineeringislackingknowledgeincrucial root functions, particularly at the molecular level. It is clear that without this understandingrootengineeringcanbeafutileundertaking.Therefore,animportant goal of this book is to outline the latest achievements in structural aspects of root systems as well as physiological relations hoping that future efforts in root engi- neeringwillbebasedonamoresolidground.Itisalsorecognizedthatpivotalsteps v vi Foreword havetostartatthelevelofinteractingpartnersusuallyassociatedwithroots,suchas mycorrhizalfungiand/orbacteria. Engineering of root system architecture is expected to support a second green revolution if crop performance under suboptimal water and nutrient supply is at stake(Chap.3).Rootgrowthmodelsshouldhelpengineeringofrootarchitecturein ordertofixtreesinshallowsoils,foundinmosturbanlandscapes(Chaps.4and14). It is hoped that this book is welcomed as an initiative for further efforts and investments in root engineering. Established scientists and academicians should enjoythebookforinnovationinthefuture.Youngscientistsandstudentsmayfind the book as a tool to undertake novel and new experiments to understand the functioning of diverse roots and for the welfare of mankind and at the same time sustaintheenvironment. Mu¨nchen,Germany BertoldHock TechnischeUniversita¨tMu¨nchen Preface Terrestrial root system is the most dynamic system in plants which regulates directly or indirectly the morphology, physiology, biochemistry, flowering, and thesynthesisofsecondarymetabolites.Itmaintainsacontinuousconductivitylink tostemandleaves.Anyblockageinupward(xylemtissues)ordownward(phloem) movementofwaterandsolutesmaydamagetheplants.Averagescientistsandplant biologistsbelievethatitisanorganofanchorageintothesoilandtransportationof mineralsandwater.Thisisnottrue. Theprimeaimandtheobjectiveofthebookaretohighlightthevariousessential rolesofrootsandtheirinteractionwithdiversemicroorganismswhicharelocalized in the root system and/or in the vicinity, e.g., endophytes, rhizosphere (mycorrhi- zosphere), and non-rhizosphere. These are under the influence of root exudates (aminoacids,sugars,andgrowthhormones).Microbialinteractionhasdeepinflu- enceonplantgrowth,flowering,fruiting,productionofsecondarymetabolites,and in combating biotic and abiotic stresses. In modern biology teachers and students areforgettingtheroleofrootsystemwhichissubterranean,andthebiomassisas enormousasthatofaerialportion.Theypreventsoilerosionandplayvitalrolein maintainingsoilhealth. The volume with 22 chapters, cleverly prepared by internationally recognized academicians, will serve and motivate the readers to value the root system and exploreforbetteruseofmankindandpreservationofourecosystem. Murcia,Spain Asuncio´nMorte Noida,India AjitVarma vii . Contents PartI AnatomicalandMorphologicalStrategiesofRoots 1 AnatomyofRootfromEyesofaMicrobiologist. . . . . . . . . . . . . . . 3 SmritiShrivastava,RamPrasad,andAjitVarma 2 RoleofPhiCellsUnderAbioticStressinPlants. . . . . . . . . . . . . . . 23 NievesFerna´ndez-Garc´ıa,CarmenLo´pez-Berenguer, andEnriqueOlmos 3 RootSystemArchitecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 BeataOrman-Ligeza,Rene´ Civava,SophiedeDorlodot, andXavierDraye 4 RootGrowthModelBasedonSwarmIntelligence. . . . . . . . . . . . . 57 Tome´ Matos,CristinaCruz,andLu´ısCorreia 5 TheDevelopmentoftheMaizeRootSystem:RoleofAuxin andEthylene. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Mar´ıaVictoriaAlarco´n,PedroG.Lloret,andJulioSalguero PartII RhizosphereandMicroorganisms 6 Mycorrhizosphere:TheRoleofPGPR. . . . . . . . . . . . . . . . . . . . . . 107 RosarioAzco´n 7 HowRootStructureDefinestheArbuscularMycorrhizal SymbiosisandWhatWeCanLearnfromIt?. . . . . . . . . . . . . . . . . 145 BeatrizDreyer,MarioHonrubia,andAsuncio´nMorte 8 HowEctomycorrhizaeStructuresBoosttheRootSystem?. . . . . . . 171 JavierParlade´,BeatrizA´gueda,LuzMarinaFerna´ndez-Toira´n, FernandoMart´ınez-Pen˜a,andAnaMar´ıadeMiguel ix