title: Impact of biotic and a-biotic parameters on structure and function of microbial communities living on sclerotia of the soil-borne pathogenic fungusRhizoctonia solani.
abstract: The plant pathogenRhizoctonia solaniis very difficult to control due to its persistent, long-living sclerotial structures in soil. Sclerotia are the main source of infection forRhizoctoniadiseases, which cause high yield losses on a broad host range world-wide. Little is known about micro-organisms associated with sclerotia in soil. Therefore, microbial communities of greenhouse and field incubatedRhizoctoniasclerotia were analysed by a multiphasic approach. Using microbial fingerprints performed by PCR-SSCP, sclerotia-associated bacterial communities showed a high diversity, whereas only a few fungi could be detected. Statistical analysis of fingerprints revealed the influence of soil types, incubation conditions (greenhouse, field), and incubation time (5 and 12 weeks) on the bacterial as well as fungal community. No significant differences were found for the microbial community associated with differentRhizoctoniaanastomosis sub-groups (AG 1-IB and AG 1-IC).Rhizoctoniasclerotia are an interesting bio-resource: high proportions of fungal cell-wall degrading isolates as well as those with antagonistic activity towardsR. solaniwere found. While a fraction of 28.4% of sclerotia-associated bacteria (=40 isolates) with antagonistic properties was determined, only 4.4% (=6 isolates) of the fungal isolates were antagonistic. We identified strong antagonists of the generaBacillus,Enterobacter,Pseudomonas, andStenotrophomonas, which can be used as biological control agents incorporated in soil or applied toRhizoctoniahost plants.
authors.affiliation: Graz University of Technology, Institute for Environmental Biotechnology, Petersgasse 12, A-8010 Graz, Austria ; ACIB GmbH, Petersgasse 14, A-8010 Graz, Austria.
authors.forename: Christin
authors.initials: C
authors.lastname: Zachow
authors.affiliation: Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, D-14979 Großbeeren, Germany.
authors.forename: Rita
authors.initials: R
authors.lastname: Grosch
authors.affiliation: Graz University of Technology, Institute for Environmental Biotechnology, Petersgasse 12, A-8010 Graz, Austria.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Berg
keywords: Antagonists; Biocontrol; Microbial fingerprints; Sclerotia