Regardless of the exact effects that Che1 signaling has on cell surface changes which are currently investigated in our laboratory, the data obtained here show that attachment of A. brasilense is increased by nitrogen limitation and further suggests that it depends on sugar-exposed residues that have lectin-binding properties, in agreement with the proposition made previously by Mora et al. (2008). Increasing attachment of A. brasilense to root surfaces may thus ultimately depends on fine-tuning metabolic activities, including limiting nitrogen availability
that is shown here as a key modulator of attachment to surfaces. The authors thank members of MG 132 the Alexandre’s and Doktycz’s laboratory for careful comments on the manuscript. This work was supported by a NSF CAREER award (MCB-0622277) and MCB-0919819 to G.A. and by the Genomic Science Program of the Office of Biological and Environmental Research, US DOE. Oak Ridge National Ku-0059436 mw Laboratory is managed by UT-Battelle, LLC, for the US Department of Energy under Contract no. DE-AC05-00OR22725. “
“The effect of sublethal concentrations
(below the recommended field doses) of propiconazole and tebuconazole on the amount of tri transcripts and accumulation of trichothecenes by three Fusarium graminearum isolates of 3ADON, 15ADON, and NIV chemotypes was examined on yeast extract sucrose agar (YES) medium. RT-qPCR analyses showed higher tri4, tri5, and tri11 transcript levels in cultures of all three F. graminearum isolates supplemented with sublethal concentrations of azoles as compared to those in nontreated control, although the fold changes in the amount of tri transcripts differed according to the type of azole used. Mycotoxin analysis revealed higher increase in trichothecene accumulation in most of the tebuconazole-treated samples of all chemotypes tested. A huge increase in all trichothecene compounds was revealed in samples of all F. graminearum isolates treated with
5 mg L−1 of tebuconazole. An inducing effect of azoles on trichothecene accumulation in the grain was confirmed in an in planta experiment; however, the results obtained were inconsistent. A higher amount of trichothecenes and fungal DNA was quantitated in two grain samples Dipeptidyl peptidase treated with sublethal propiconazole concentrations. In contrast, no significant increase in trichothecene levels was revealed in grain samples treated with sublethal concentrations of tebuconazole. The Fusarium graminearum (teleomorph Gibberella zeae) species complex is one of the most important causal agents of Fusarium head blight (FHB) of wheat and other cereals worldwide (Ward et al., 2008). Fusarium graminearum contaminates the grain with high levels of type B trichothecenes: deoxynivalenol (DON) and nivalenol (NIV) and their acetyl derivatives. Contamination of plant products with these toxins poses a significant risk to food safety and animal health (Foroud & Eudes, 2009). Three major F.