ENDOPHYTES: STRUCTURAL AND FUNCTIONAL DIVERSITY AND BIOTECHNOLOGICAL APPLICATIONS IN CONTROL OF PLANT PATHOGENS



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Abstract

Endophytes are an interesting group of plant-associated bacteria that live inside plants and show neutral or beneficial interaction with their host plants. The structure of bacterial communities in endophytic microenvironments of important crops (different cultivars of potato, lettuce, and sugar beet) and native plants (different bryophyte species) was analyzed by a multiphasic approach at different field sites in Europe. Interestingly, results of the cultivation-independent approaches using Single-Strand Conformation Polymorphism (SSCP) and/or Terminal Restriction Fragments Length Polymorphism (T-RFLP) of 16S rRNA genes amplified by universal as well as group-specific and functional primers revealed a high diversity and specificity of endophytic bacterial communities. The antagonistic potential of endophytic bacteria, which was determined by screening for in vitro antagonism against different pathogens (bacteria, fungi, protists, and nematodes) ranged from 5 to 43 %. An impressive, phylogenetically diverse spectrum of antagonistic strains was found. The indigenous antagonistic potential of endophytic bacteria was influenced by the plant genotype and developmental stage, the internal microenvironment, and the soil type. A screening strategy for biocontrol strains resulted in the selection of promising candidates. These strains were evaluated in greenhouse and field trials regarding their efficiency to control pathogens under in situ conditions. One product (RhizoStar®) on the basis of serratia plymuthica HRO-C48 to control Verticillium wilt on different host plants was developed. For other promising candidates likePseudomonas trivialis 3Re2-7 (B3) and serratia plymuthica 3Re4-18 (B4) a biological control strategy against the soil-borne pathogen Rhizoctonia solani will be established. These studies were funded by the Deutsche Forschungs-gemeinschaft, the Ministry of Consumer Protection, Food and Agriculture (Germany) and by private industries (KWS SAAT AG, Strawberry farm Rovershagen, and Nor-ddeutsche Pflanzenzucht Hans-Georg Lembke KG, Ho-henlieth, Germany) by grants to G.B.

About the authors

Gabriele Berg

Graz University of Technology, Institute of Environmental Biotechnology, Graz, Austria

Henry M?ller

KWS SAAT AG, , Einbeck, Germany

Christin Zachow

Graz University of Technology, Institute of Environmental Biotechnology, Graz, Austria

Katja Opelt

Graz University of Technology, Institute of Environmental Biotechnology, Graz, Austria

Katja Scherwinski

Graz University of Technology, Institute of Environmental Biotechnology, Graz, Austria

Ralf Tilcher

KWS SAAT AG, , Einbeck, Germany

Andreas Ulrich

Leibniz-Zentrum f?r Agrarland cschaftsforschung (ZALF), Institut f?r Landschaftsstoffdynamik, M?ncheberg, Germany

Johannes Hallmann

Biologische Bundesanstalt f?r Land- und Forstwirtschaft, Institut f?r Nematologie und Wirbeltierkunde, M?nster, Germany

Rita Grosch

Institute of Vegetable and Ornamental Crops, Gro?beeren, Germany

Angela Sessitsch

Austrian Research Centers GmbH, Seibersdorf, Austria

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Copyright (c) 2008 Berg G., M?ller H., Zachow C., Opelt K., Scherwinski K., Tilcher R., Ulrich A., Hallmann J., Grosch R., Sessitsch A.

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