Soil biota in natural and managed plant communities ... - CBCS 2013

Soil biota in natural and managed plant communities ... - CBCS 2013

Soil biota in natural and managed plantcommunities: progress, challenges andopportunitiesPedro M. Antunes

We don’t understand…! …why some plant species are highly abundant while othersoccur at low densities

SystemsNatural Agriculture Invaded

Proposed frameworks to explain why someplants are abundant and others are rare! Resource partitioningH. L. Reynolds et al., 2003 Ecology

de Deyn and van der Putten 2005, TREE! Resource partitioningwhile neglecting plantmicrobe interactions failsto explain plantcommunity dynamics(Miller et al., 2005; Beveret al., 2012)! The role of below-groundsoil organisms interactingwith plant roots has beengaining increasingattention in recent years! However, themechanisms regulatingthese processes are verypoorly understood

de Deyn and van der Putten 2005, TREEUnknown (rhizosphere)biodiversityThe Fungi: 1, 2, 3 ,… 5.1 million species? (Blackwell, 2011)

The concept of feedbackBever et al. 2013, Ann. Rev. Microbiol.

Feedbacks and plant communities - evidenceKlironomos 2002, Nature 417:67

Mycorrhizal fungiwith AMFwithout AMF

Source: Jim Deacon and Thomas Fester

Schüßler and Walker 2010

Rillig et al 2010. Soil Biol BiochemSoil responsesGlucoseROCSoil! AM fungi alone can be sufficient to form and/or maintainwater-stable soil macroaggregates

Questions – biotic interactions! Can plant and soil responses be predicted based onbiota identity?! How important is pathogen protection by AMF?! Are local adaptations to environmental conditionsimportant for symbiotic functioning and, thus, to plantgrowth responses?

Biomass responsesPlant growth4 AMF species?Can plant growth responses to AMF be predicted based on AMF identity?

Three plant species...Achillea millefolium(Asteraceae)Bromus inermis(Poaceae)Medicago sativa(Fabaceae)

... each inoculated with 56 AM isolates of 16 species(or left uninoculated) most of which were obtained fromINVAM (International Culture Collection of Vesicular Arbuscular Mycorrhizal Fungi)Glomerales (Gr. A + B)Diversi -sporalesArchaeosporalesParaglomeralesused AM genera (# sp.):Glomus (3+2)Acaulospora (2)Entrophospora (2)Glomus Gr. C,DiversisporaPacisporaGigaspora (2)Scutellospora (2)Archaeospora (2)GeosiphonParaglomus (1)Gl. mosseaeSc. heterogamasources: phylogenetic tree: http://invam.caf.wvu.eduAr. leptoticha

... individual plants of each AM isolate * host combination (n= 10)were grown in 500 ml containers; (total of 1740 replicate units)

Mycorrhizal plants grew 17% larger than controls...Growth promotion relative to controls40%30%Medicago20%Achillea10%Bromus0%12 16 20Harvest time [weeks]... and the plant species differin their overall “responsiveness”Koch, Antunes, Maherali and Klironomos (submitted)

Koch, Antunes, Maherali and Klironomos (submitted)

Antunes et al 2006, Soil Biol BiochemMutualism-mutualism interactionsNodules 10.8 aArbuscules: 32 aHyphae: 58 aNodules 6.6 bArbuscules: 22 bHyphae: 37 b

OOOOOHHHHHHHHB. japonicumCellmembrane123253RRLegend:Myc factorNod factorChitinaseRReceptorOOOOHHHHHHHHHHOOOOOHHHHHHHHHHOOOOOHHHHHHHHHHHHGenisteinDaidzeinCoumestrolGlyciteinOOOOHHHHHHHHHHHHFormononetin5?? OOOOOHHHHHHHHHHOOOOHHHHHHHHHHOOOOOHHHHHHHHOOOOOHHHHHHHHHHHHOOOOHHHHHHHHHHHHFurther expression ofprotein and enzymesinvolved in thesynthesis of flavonoidsFlavonoidsLCOs: Lipochitooligosaccharides4LCOsAMF hypha

Other responses – AMF- pathogen interactionsNewsham et al., 1995, J. Ecol. 83:991

Wehner et al., 2010 Pedobiol.Plant pathogen protection byarbuscular mycorrhizas: A role forfungal diversity?! Improved nutrient status of the host plant! Competitive interactions with pathogenic fungi! Architectural changes in the root system! Microbial community changes in the rhizosphere! Activation of plant defense mechanisms

Indigenous arbuscular mycorrhizalfungal assemblages protectgrassland host plants from pathogens

The study site (ODERHÄNGE MALLNOW)

Experimental design14 plants x 4 Soil microbial treatments x 10 replicates = 980 conetainers

ResultsWehner et al., 2011, PLosOne

ResultsWehner et al., 2011, PLosOne

Isolate Identity Determines PlantTolerance to Pathogen Attack inAssembled Mycorrhizal communities

ResultsCONTROLPATHOGENLewandowski et al., PLoSONE 2013

Local adaptations

What we don’t knowLittle is known about the microbial andfunctional diversity responsible for plant-soilfeedbacksopening the black box


Balance between pathogens andmutualisms and how do theyinteract?! Integrating pyrosequencing, with functional responseexperiments to create database of abundant andkeystone species! Take into consideration co-adaptation in the study ofbest consortia

New methods to determine functionaloutcomes - pyrosequencing

Answers! Does mutualism prevail across the Glomeromycota?! Yes! Can plant responses to AMF be predicted based on AMF species identity?! No! How important is pathogen protection?! Some preliminary evidence that it might be important! Are AMF adaptations to environmental conditions important for symbioticfunctioning and, thus, to plant growth responses?! Evidence for biogeographical structure

Acknowledgements! Prof. John Klironomos UBC Okanagan! Prof. Cristina Cruz FCUL! Prof. Filomena Caeiro FCUL! Prof. Matthias Rillig Free University Berlin! Prof. Joe Morton University of West Virginia (INVAM)! Dr. Alexander Koch UBC Okanagan! Jeannine Wehner, Anika Lehman (Berlin), Teresa Dias, LauraSanderson, Thaddeus Lewandowski (Algoma University), MartaDelgado (FCUL)

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