Selection of Streptomyces against soil borne fungal pathogens by a standardized dual culture assay and evaluation of their effects on seed germination and plant growth

BMC Microbiology

Research Article

Maria Bonaldi¹  Paolo Cortesi¹  Andrea Kunova¹  Marco Saracchi¹  Cristina Pizzatti¹  Xiaoyulong Chen¹ 

[1] Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, via Giovanni Celoria, 2, 20133, Milan, Italy;

关键词: Dual culture assay;    Antagonism;    Antibiosis;    Biological control;    Seed colonization;    Plant growth promotion;   

DOI  :  10.1186/s12866-016-0886-1

 received in 2016-04-16, accepted in 2016-11-03,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundIn the search for new natural resources for crop protection, streptomycetes are gaining interest in agriculture as plant growth promoting bacteria and/or biological control agents. Because of their peculiar life cycle, in which the production of secondary metabolites is synchronized with the development of aerial hyphae and sporulation, the commonly used methods to screen for bacterial antagonists need to be adapted.ResultsThe dual culture assay was standardized in terms of inoculation timing of Streptomyces antagonist and pathogen, and growth rate of different fungal pathogens. In case of fast-growing fungi, inoculation of the antagonist 2 or 3 days prior to the pathogen resulted in significantly stronger inhibition of mycelium growth. One hundred and thirty Streptomyces strains were evaluated against six destructive soil borne pathogens. The activity of strains varied from broad-spectrum to highly specific inhibition of individual pathogens. All strains inhibited at least one tested pathogen. Three strains, which combined the largest broad-spectrum with the highest inhibition activity, were selected for further characterization with four vegetable species. All of them were able to colonize seed surface of all tested vegetable crops. They mostly improved radicle and hypocotyl growth in vitro, although no statistically significant enhancement of biomass weight was observed in vivo. Occasionally, transient negative effects on germination and plant growth were observed.ConclusionsThe adapted dual culture assay allowed us to compare the inhibition of individual Streptomyces strains against six fungal soil borne pathogens. The best selected strains were able to colonize the four vegetable crops and have a potential to be developed into biocontrol products. Although they occasionally negatively influenced plant growth, these effects did not persist during the further development. Additional in vivo studies are needed to confirm their potential as biological control or plant growth promoting agents.

【 授权许可】

CC BY   
© The Author(s). 2016