Phytopathology (2014) 104, 1201-1207

Luca Sella, Katia Gazzetti, Carla Castiglioni, Wilhelm Schäfer and Francesco Favaron (2014)
Fusarium graminearum possesses virulence factors common to Fusarium head blight of wheat and seedling rot of soybean but differing in their impact on disease severity
Phytopathology 104 (11), 1201-1207
Abstract: Fusarium graminearum is a toxigenic fungal pathogen that causes Fusarium head blight (FHB) and crown rot on cereal crops worldwide. This fungus also causes damping-off and crown and root rots at the early stage of crop development in soybean cultivated in North and South America. Several F. graminearum genes were investigated for their contribution to FHB in cereals but no inherent study is reported for the dicotyledonous soybean host. In this study we determined the disease severity on soybean seedlings of five single gene disrupted mutants of F. graminearum, previously characterized in wheat spike infection. Three of these mutants are impaired on a specific function as the production of deoxynivalenol (DON, Deltatri5), lipase (DeltaFgl1), and xylanase (Deltaxyl03624), while the remaining two are MAP kinase mutants (DeltaFgOS-2, Deltagpmk1), which are altered in signaling pathways. The mutants that were reduced in virulence (Deltatri5, DeltaFgl1, and DeltaFgOS-2) or are avirulent (Deltagpmk1) on wheat were correspondently less virulent or avirulent in soybean seedlings, as shown by the extension of lesions and seedling lengths. The Deltaxyl03624 mutant was as virulent as the wild type mirroring the behavior observed in wheat. However, a different ranking of symptom severity occurred in the two hosts: the DeltaFgOS-2 mutant, that infects wheat spikelets similarly to Deltatri5 and DeltaFgl1 mutants, provided much reduced symptoms in soybean. Differently from the other mutants, we observed that the DeltaFgOS-2 mutant was several fold more sensitive to the glyceollin phytoalexin suggesting that its reduced virulence may be due to its hypersensitivity to this phytoalexin. In conclusion, lipase and DON seem important for full disease symptom development in soybean seedlings, OS-2 and Gpmk1 MAP kinases are essential for virulence, and OS-2 is involved in conferring resistance to the soybean phytoalexin.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Francesco Favaron

Research topic(s) for pests/diseases/weeds:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Fusarium graminearum	Soybean (Glycine max)
	Fusarium graminearum	Wheat (Triticum)