Impact of biotic and a-biotic parameters on structure and function of microbial communities living on sclerotia of the soil-borne pathogenic fungus .

The plant pathogen is very difficult to control due to its persistent, long-living sclerotial structures in soil. Sclerotia are the main source of infection for diseases, 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 incubated sclerotia 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 different anastomosis sub-groups (AG 1-IB and AG 1-IC). sclerotia are an interesting bio-resource: high proportions of fungal cell-wall degrading isolates as well as those with antagonistic activity towards were 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 genera , , , and , which can be used as biological control agents incorporated in soil or applied to host plants.