Fusarium verticillioides Induces Maize-Derived Ethylene to Promote Virulence by Engaging Fungal G-Protein Signaling.
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Seed maceration and contamination with mycotoxin fumonisin inflicted by Fusarium verticillioides is major disease of concern for maize producers world-wide. Meta-analyses of QTL for Fusarium ear rot resistance uncovered several ethylene (ET) biosynthesis and signaling genes within them, implicating ET in maize interactions with F. verticillioides. We tested this hypothesis using maize knock-out mutants of the 1-aminocyclopropane-1-carboxylate (ACC) synthases, ZmACS2 and ZmACS6. Infected wild-type seed emitted five-fold higher ET levels compared to controls, whereas ET was abolished in the acs2 and acs6 single and double mutants. The mutants supported reduced fungal biomass, conidia and fumonisin content. Normal susceptibility was restored in the acs6 mutant with exogenous treatment of ET precursor, ACC. Subsequently, we showed that fungal G-protein signaling is required for virulence via induction of maize-produced ET. F. verticillioides Gβ subunit and two regulators of G-protein signaling mutants displayed reduced seed colonization and decreased ET levels. These defects were rescued by exogenous application of ACC. We concluded that pathogen-induced ET facilitates F. verticillioides colonization of seed, and in turn host ET production is manipulated via G-protein signaling of F. verticillioides to facilitate pathogenesis.
Mol Plant Microbe Interact
author list (cited authors)
Park, Y., Borrego, E. J., Gao, X., Christensen, S. A., Schmelz, E., Lanubile, A., ... Kolomiets, M. V.
complete list of authors
Park, Yong-Soon||Borrego, Eli J||Gao, Xiquan||Christensen, Shawn A||Schmelz, Eric||Lanubile, Alessandra||Drab, Dillon A||Cody, Will||Yan, Huijuan||Shim, Won-Bo||Kolomiets, Michael V