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Initial Steps towards Biocontrol in Hops: Successful Colonization and Plant Growth Promotion by Four Bacterial Biocontrol Agents
Bavarian State Research Centre for Agriculture, Institute for Crop Science and Plant Breeding, Hop Breeding Research and Genome Analysis, Am Gereuth 2, D-85354 Freising, Germany
Austrian Centre of Industrial Biotechnology (ACIB GmbH), Petersgasse 14, A-8010 Graz, Austria
Graz University of Technology, Environmental Biotechnology, Petersgasse 12, A-8010 Graz, Austria
* Author to whom correspondence should be addressed.
Received: 31 August 2013; in revised form: 11 September 2013 / Accepted: 12 September 2013 / Published: 26 September 2013
Abstract: Verticillium wilt, caused by Verticillium nonalfalfae and V. dahliae, is a devastating disease in hops that can cause considerable economic crop losses. The perennial use of hops combined with the long persistence of the pathogen in soil make it difficult to suppress the disease with conventional measures. Biological control agents (BCA) are the basis of an environmentally friendly plant protection strategy that uses plant promotion and antagonistic effects of microorganisms. We evaluated the effect of four selected beneficial bacterial strains, Burkholderia terricola ZR2-12, Pseudomonas poae RE*1-1-14, Serratia plymuthica 3Re4-18, and Stenotrophomonas rhizophila DSM14405T for their use in hops. All strains were shown to be both rhizosphere and endorhiza competent, and their abundances ranged from log10 3.0 to log10 6.2 CFU g−1 root fresh weight in the endorhiza and from log10 2.9 to log10 4.7 CFU g−1 root fresh weight in the rhizosphere with B. terricola ZR2-12 showing the highest overall cell densities. Microscopic visualization of DsRed-labeled transformants with confocal laser scanning microscopy showed different colonization patterns and confirmed the rhizosphere competence. Growth promoting effects on seedlings treated with bacteria were found for S. plymuthica 3Re4-18 and S. rhizophila DSM14405T. Competent colonization and plant growth promoting effects are the most important prerequisites towards efficient biocontrol.
Keywords: Humulus lupulus; beneficial bacteria; root colonization; growth promotion; biological control; Verticillium wilt
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Maurer, K.A.; Zachow, C.; Seefelder, S.; Berg, G. Initial Steps towards Biocontrol in Hops: Successful Colonization and Plant Growth Promotion by Four Bacterial Biocontrol Agents. Agronomy 2013, 3, 583-594.
Maurer KA, Zachow C, Seefelder S, Berg G. Initial Steps towards Biocontrol in Hops: Successful Colonization and Plant Growth Promotion by Four Bacterial Biocontrol Agents. Agronomy. 2013; 3(4):583-594.
Maurer, Katja A.; Zachow, Christin; Seefelder, Stefan; Berg, Gabriele. 2013. "Initial Steps towards Biocontrol in Hops: Successful Colonization and Plant Growth Promotion by Four Bacterial Biocontrol Agents." Agronomy 3, no. 4: 583-594.