title: Native root-associated bacteria rescue a plant from a sudden-wilt disease that emerged during continuous cropping.
abstract: Plants maintain microbial associations whose functions remain largely unknown. For the past 15 y, we have planted the annual postfire tobacco Nicotiana attenuata into an experimental field plot in the plant's native habitat, and for the last 8 y the number of plants dying from a sudden wilt disease has increased, leading to crop failure. Inadvertently we had recapitulated the common agricultural dilemma of pathogen buildup associated with continuous cropping for this native plant. Plants suffered sudden tissue collapse and black roots, symptoms similar to a Fusarium-Alternaria disease complex, recently characterized in a nearby native population and developed into an in vitro pathosystem for N. attenuata. With this in vitro disease system, different protection strategies (fungicide and inoculations with native root-associated bacterial and fungal isolates), together with a biochar soil amendment, were tested further in the field. A field trial with more than 900 plants in two field plots revealed that inoculation with a mixture of native bacterial isolates significantly reduced disease incidence and mortality in the infected field plot without influencing growth, herbivore resistance, or 32 defense and signaling metabolites known to mediate resistance against native herbivores. Tests in a subsequent year revealed that a core consortium of five bacteria was essential for disease reduction. This consortium, but not individual members of the root-associated bacteria community which this plant normally recruits during germination from native seed banks, provides enduring resistance against fungal diseases, demonstrating that native plants develop opportunistic mutualisms with prokaryotes that solve context-dependent ecological problems.
authors: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany.
authors: Rakesh
authors: R
authors: Santhanam
authors: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany.
authors: Van Thi
authors: VT
authors: Luu
authors: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany.
authors: Arne
authors: A
authors: Weinhold
authors: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany.
authors: Jay
authors: J
authors: Goldberg
authors: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany.
authors: Youngjoo
authors: Y
authors: Oh
authors: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany Baldwin@ice.mpg.de.
authors: Ian T
authors: IT
authors: Baldwin
mesh_terms: D000528:Alternaria / Q000145:classification / Q000235:genetics / Q000502:physiology; D000898:Antibiosis / Q000502:physiology*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D005658:Fungi / Q000145:classification / Q000235:genetics / Q000502:physiology*; D005670:Fusarium / Q000145:classification / Q000235:genetics / Q000502:physiology; D054884:Host-Pathogen Interactions; D059013:Microbial Consortia / Q000502:physiology; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology*; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis; D014026:Nicotiana / Q000254:growth & development / Q000382:microbiology*
chemical_list: D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S
keywords: Alternaria; Fusarium; Nicotiana attenuata; microbiome function; plant disease resistance