EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
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SESSION 2: SECONDARY METABOLITES – BIOCHEMISTRY,<br />
BIOSYNTHESIS, FEED AND FOOD SAFETY<br />
Ecological role <strong>of</strong> mycotoxins produced by Fusarium<br />
graminearum<br />
M. Abid 1 , L. Fayolle 1 , C. Héraud 1 , P. Mangin 2 , L. Falchetto 2 , N. Gautheron 1 , J.<br />
Laurent 1 , E. Gautheron 1 , V. Edel-Hermann 1 , C. Steinberg 1<br />
1 INRA, UMR1347 Agroécologie 17 rue Sully, BP 86510, F-21000 Dijon, France; 2 INRA, UE Domaine<br />
d’Epoisses, F-21110 Bretenières, France<br />
E-mail: christian.steinberg@dijon.inra.fr<br />
Fusarium graminearum is a plant pathogenic fungus, producing mycotoxins some<br />
<strong>of</strong> which remain in the crop residues let in the field after harvest. Whether the<br />
presence <strong>of</strong> mycotoxins in the crop residues gives an advantage to F.<br />
graminearum to survive and develop a primary inoculum in the presence <strong>of</strong> the<br />
whole soil biota including fungi, bacteria, protozoa, nematodes and earthworms<br />
was tested. The impact <strong>of</strong> deoxynivalenol (DON) on the soil communities was<br />
evaluated in the field and in microcosms, in wheat and in maize residues under<br />
tillage and no-tillage conditions. The disease development and the yield were<br />
noted in the field experiment. Some DON resistant active fungal decomposers<br />
and nitrogen fixing bacteria were picked and the dynamics <strong>of</strong> F. graminearum was<br />
observed in their presence, in the presence or absence <strong>of</strong> DON.<br />
DON in crop residues had an impact on the biotic components <strong>of</strong> the soil but the<br />
impact depended on the communities and on the location <strong>of</strong> the residues. The<br />
molecular biomass showed that fungal and bacterial densities were significantly<br />
affected by DON. The latter played significant role on the structure <strong>of</strong> bacterial<br />
and protozoan community while the nematodes and fungal communities remained<br />
unaffected. However, the minimal inhibitory concentration tests revealed that the<br />
susceptibility <strong>of</strong> some competitive fungal strains to DON was dose-dependent.<br />
Earthworms (Lumbricus terrestris) were not affected by the presence <strong>of</strong><br />
mycotoxin. The degradation <strong>of</strong> DON in the residues was dependent on the time,<br />
the location <strong>of</strong> residues and the soil biota.<br />
Obviously DON gave no advantage for the survival and development <strong>of</strong> primary<br />
inoculum during the decomposition <strong>of</strong> crop residues in the soil. Moreover fungal<br />
decomposers can be selected on their enzymatic potential towards organic matter<br />
more than on the DON resistance to increase the degradation <strong>of</strong> the straw left at<br />
the surface and limit the subsequent development <strong>of</strong> F. graminearum.<br />
Keywords: Biological control, habitat, soil ecology, saprophytic phase<br />
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