Sugar Beet-Associated Bacterial and Fungal Communities Show a High Indigenous Antagonistic Potential Against Plant Pathogens

• Published in: Microbial ecology Vol. 55; no. 1; pp. 119 - 129
• Main Authors: Zachow, Christin, Tilcher, Ralf, Berg, Gabriele
• Format: Journal Article
• Language: English
• Published: New York New York : Springer-Verlag 01.01.2008; Springer Science + Business Media, Inc; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Antagonism; Antagonists; Antibiosis; Aphanomyces; Aphanomyces - growth & development; Aphanomyces - pathogenicity; Aphanomyces cochlioides; Ascomycota; Ascomycota - growth & development; Ascomycota - pathogenicity; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - growth & development; Bacteria - isolation & purification; bacterial communities; Beet sugar; Beta vulgaris; Beta vulgaris - microbiology; Biological and medical sciences; Biomedical and Life Sciences; classification; Conformation; Developmental stages; Ecology; Ecosystem; Fundamental and applied biological sciences. Psychology; fungal communities; Fungi; Fungi - classification; Fungi - genetics; Fungi - growth & development; Fungi - isolation & purification; genetics; Geoecology/Natural Processes; growth & development; Host range; Indigenous plants; isolation & purification; Life Sciences; Microbacterium; Microbacterium testaceum; Microbial activity; Microbial Ecology; Microbiology; Microbiomes; Microenvironments; Microorganisms; Molecular Sequence Data; Nature Conservation; pathogenicity; Pathogens; Phoma; Phoma betae; Phyllosphere; Phyllosphere microorganisms; plant development; Plant Diseases; Plant Diseases - microbiology; Plant Leaves; Plant Leaves - microbiology; Plant pathogens; Plant Roots; Plant Roots - microbiology; Plants; Polymorphism; Polymorphism, Single-Stranded Conformational; Pseudomonas; Pythium; Pythium - growth & development; Pythium - pathogenicity; Pythium ultimum; Rhizoctonia; Rhizoctonia - growth & development; Rhizoctonia - pathogenicity; Rhizoctonia solani; Rhizosphere; Rhizosphere microorganisms; ribosomal RNA; RNA, Ribosomal, 16S; RNA, Ribosomal, 16S - genetics; rRNA 16S; rRNA 18S; Saccharides; screening; Sequence Analysis, DNA; single-stranded conformational polymorphism; Subtercola; Sugar; sugar beet; Sugar beets; sugars; Thanatephorus cucumeris; Water Quality/Water Pollution; Europe; Anastomosis Group; Single Strand Conformation Polymorphism; Sugar Beet; Fungal Community; Rhizoctonia Solani; Plant pathogen; Phoma betae; Aphanomyces cochlioides; Beta vulgaris var. saccharata; 18S-RNA; Single strand conformation polymorphism; Fungi; Antagonism; Dicotyledones; Pathogenic; Angiospermae; Phyllosphere; 16S-RNA; Bacteria; Fungi Imperfecti; Antagonist; Localization; Microbial community; Stramenopila; Composition; Oomycota; Sugar plant; Chenopodiaceae; Rhizosphere; Isolate; Spermatophyta; Microorganism
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-007-9257-7

The aim of this study was to analyze microbial communities in/on sugar beet with special focus on antagonists toward plant pathogens. For this purpose, the composition of microorganisms isolated from the rhizosphere, phyllosphere, endorhiza, and endosphere of field-grown sugar beet plants was analyzed by a multiphasic approach at three different plant development stages at six locations in Europe. The analysis of microbial communities by Single Strand Conformation Polymorphism (SSCP) of 16S/18S rRNA clearly revealed the existence of discrete microenvironment- and site-specific patterns. A total of 1952 bacterial and 1344 fungal isolates screened by dual testing for antagonism toward the pathogens Aphanomyces cochlioides, Phoma betae, Pythium ultimum, and Rhizoctonia solani resulted in 885 bacterial (=45%) and 437 fungal (=33%) antagonists. In general, the indigenous antagonistic potential was very high and influenced by (a) the location, (b) the plant developmental stage, and (3) the microenvironment. Furthermore, we showed for the first time that the antagonistic potential was highly specific for each target pathogen. The majority of antagonistic microorganisms suppressed only one pathogen (bacteria: 664 = 75%; fungi: 256 = 59%), whereas the minority showed a broad host range (bacteria: 4 = 0.5%; fungi: 7 = 1.6%). The bacterial communities harbored the highest antagonistic potential against P. ultimum, whereas the fungal communities contained more antagonists against A. cochlioides and R. solani. In contrast to their high proportion, only a low diversity of antagonists at genotypic and species level was found. Novel antagonistic species, e.g., Subtercola pratensis or Microbacterium testaceum were found in the internal part of the sugar beet body.