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  • Root-hair endophyte stacking in finger millet creates a physicochemical barrier to trap the fungal pathogen Fusarium graminearum.

Root-hair endophyte stacking in finger millet creates a physicochemical barrier to trap the fungal pathogen Fusarium graminearum.

Nature microbiology (2016-09-27)
Walaa K Mousa, Charles Shearer, Victor Limay-Rios, Cassie L Ettinger, Jonathan A Eisen, Manish N Raizada
ABSTRACT

The ancient African crop, finger millet, has broad resistance to pathogens including the toxigenic fungus Fusarium graminearum. Here, we report the discovery of a novel plant defence mechanism resulting from an unusual symbiosis between finger millet and a root-inhabiting bacterial endophyte, M6 (Enterobacter sp.). Seed-coated M6 swarms towards root-invading Fusarium and is associated with the growth of root hairs, which then bend parallel to the root axis, subsequently forming biofilm-mediated microcolonies, resulting in a remarkable, multilayer root-hair endophyte stack (RHESt). The RHESt results in a physical barrier that prevents entry and/or traps F. graminearum, which is then killed. M6 thus creates its own specialized killing microhabitat. Tn5-mutagenesis shows that M6 killing requires c-di-GMP-dependent signalling, diverse fungicides and resistance to a Fusarium-derived antibiotic. Further molecular evidence suggests long-term host-endophyte-pathogen co-evolution. The end result of this remarkable symbiosis is reduced deoxynivalenol mycotoxin, potentially benefiting millions of subsistence farmers and livestock. Further results suggest that the anti-Fusarium activity of M6 may be transferable to maize and wheat. RHESt demonstrates the value of exploring ancient, orphan crop microbiomes.

MATERIALS
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Brand
Product Description

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Calcofluor White Stain, suitable for microbiology
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