Plant-specific selection of drought-resistant biological control agents against soil-borne pathogens

Martina Köberl, Elshahat M. Ramadan, Kornelia Smalla, Gabriele Berg

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Desert agriculture is a strongly growing field of land use. However, emerging problems with soil-borne pathogens limit the yield. Biological control agents (BCAs), which are able to suppress soil-borne pathogens, are promising candidates for plant protection but for desert application specific, drought-resistant strains are required. Here we report a stepwise selection procedure of BCAs from one of the most prominent organic desert farms SEKEM in Egypt. In a first step, we characterized the bacterial and fungal communities of the target habitat - the rhizospheres and endorhiza of medical plants (Matricaria chamomilla L., Calendula officinalis L. and Solanum distichum Schumach. & Thonn.). The bacterial communities were highly different - for the plant species as well as for both investigated microenvironments. The fungal community was less discriminative but characterized by phytopathogens. In a cultivation-dependent approach, isolates from all parts were obtained and characterized by their anti-phytopathogenic potential against fungi (Fusarium culmorum, Rhizoctonia solani, Verticillium dahliae), bacteria (Ralstonia solanacearum) and nematodes. In parallel, genotypic diversity was analysed by ARDRA and BOX-PCR. Both procedures resulted in the selection of 46 unique, broad-spectrum antagonists. However, their diversity was low: 89% of the selected strains belonged to the Bacillus/Paenibacillus cluster. Bacillus subtilis (subsp. subtilis and spizizenii) was the main species identified in cultures and also a dominant band in soil, rhizosphere and endorhiza in microbial fingerprints. Furthermore, using a metagenomic approach, it was shown that Firmicutes and especially Bacillus was enriched in SEKEM soil in comparison with the surrounding desert. In contrast, from the original desert soil, diverse antagonistic Streptomyces strains were selected.
Original languageEnglish
Title of host publicationPlant growth-promoting rhizobacteria (PGPR) for sustainable agriculture
Place of PublicationBeijing, China
PublisherChina Agricultural Science and Technology Press
Pages199-206
ISBN (Print)978-751-160-611-2
Publication statusPublished - 2011
EventAsian PGPR Conference - Beijing, China
Duration: 21 Aug 201124 Aug 2011

Conference

ConferenceAsian PGPR Conference
CountryChina
CityBeijing
Period21/08/1124/08/11

Fields of Expertise

  • Sonstiges

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