Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2015 Feb 6:6:25.
doi: 10.3389/fmicb.2015.00025. eCollection 2015.

Colonization of lettuce rhizosphere and roots by tagged Streptomyces

Maria Bonaldi  1 , Xiaoyulong Chen  1 , Andrea Kunova  1 , Cristina Pizzatti  1 , Marco Saracchi  1 , Paolo Cortesi  1
Affiliations

Colonization of lettuce rhizosphere and roots by tagged Streptomyces

Maria Bonaldi et al. Front Microbiol. .

Abstract

Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plasmid harboring an enhanced green fluorescent protein marker and resistance to apramycin. The fitness of transformants was compared to the wild-type strains and all of them grew and sporulated at similar rates and retained the production of enzymes and selected secondary metabolites as well as in vitro inhibition of S. sclerotiorum. The tagged ZEA17I strain was selected to study the dynamics of lettuce roots and rhizosphere colonization in non-sterile growth substrate. The transformed strain was able to colonize soil, developing roots, and rhizosphere. When the strain was inoculated directly on the growth substrate, significantly more t-ZEA17I was re-isolated both from the rhizosphere and the roots when compared to the amount obtained after seed coating. The re-isolation from the rhizosphere and the inner tissues of surface-sterilized lettuce roots demonstrated that t-ZEA17I is both rhizospheric and endophytic.

Keywords: Lactuca sativa; Sclerotinia sclerotiorum; biocontrol; rhizosphere competence; streptomycetes.

PubMed Disclaimer

Figures

FIGURE 1
FIGURE 1
Microscopic observation of EGFP expression in transformed Streptomyces strains by bright field (left) and epifluorescence microscopy (right). Mycelium and spore chains of (A) the strain t-ZEA17I, (B) the strain t-FT05W, and (C) spore chains of the strain t-CX16W. Scale bar, 20 μm.
FIGURE 2
FIGURE 2
Mycelium growth of the wild-type and transformed Streptomyces spp. strains, (A) CX14W and (B) CX16W. Vertical bars represent SE (N = 3).
See this image and copyright information in PMC

References

    1. Aeron A., Kumar S., Pandey P., Maheshwari D. K. (2011). “Emerging role of plant growth promoting rhizobacteria in agrobiology,” in Bacteria in Agrobiology: Crop Ecosystems ed.Maheshwari D. K. (Berlin: Springer; ), 1–36 10.1007/978-3-642-18357-7_1 - DOI
    1. Bano N., Musarrat J. (2003). Characterization of a new Pseudomonas aeruginosa strain NJ-15 as a potential biocontrol agent. Curr. Microbiol. 46 0324–0328 10.1007/s00284-002-3857-8 - DOI - PubMed
    1. Bashan Y., Puente M. E., Rodriguezmendoza M. N., Toledo G., Holguin G., Ferreracerrato R., et al. (1995). Survival of Azospirillum brasilense in the bulk soil and rhizosphere of 23 soil types. Appl. Environ. Microbiol. 61 1938–1945. - PMC - PubMed
    1. Berg G. (2009). Plant–microbe interactions promoting plant growth and health: perspectives for controlled use of microorganisms in agriculture. Appl. Microbiol. Biotechnol. 84 11–18 10.1007/s00253-009-2092-7 - DOI - PubMed
    1. Bonaldi M., Kunova A., Saracchi M., Sardi P., Cortesi P. (2014). Streptomycetes as biological control agents against basal drop. Acta Hortic. 1044 313–318.