Effects of Bacillus amyloliquefaciens FZB42 on lettuce growth and health under pathogen pressure and its impact on the rhizosphere bacterial community

PLoS One. 2013 Jul 23;8(7):e68818. doi: 10.1371/journal.pone.0068818. Print 2013.

Abstract

The soil-borne pathogen Rhizoctonia solani is responsible for crop losses on a wide range of important crops worldwide. The lack of effective control strategies and the increasing demand for organically grown food has stimulated research on biological control. The aim of the present study was to evaluate the rhizosphere competence of the commercially available inoculant Bacillus amyloliquefaciens FZB42 on lettuce growth and health together with its impact on the indigenous rhizosphere bacterial community in field and pot experiments. Results of both experiments demonstrated that FZB42 is able to effectively colonize the rhizosphere (7.45 to 6.61 Log 10 CFU g(-1) root dry mass) within the growth period of lettuce in the field. The disease severity (DS) of bottom rot on lettuce was significantly reduced from severe symptoms with DS category 5 to slight symptom expression with DS category 3 on average through treatment of young plants with FZB42 before and after planting. The 16S rRNA gene based fingerprinting method terminal restriction fragment length polymorphism (T-RFLP) showed that the treatment with FZB42 did not have a major impact on the indigenous rhizosphere bacterial community. However, the bacterial community showed a clear temporal shift. The results also indicated that the pathogen R. solani AG1-IB affects the rhizosphere microbial community after inoculation. Thus, we revealed that the inoculant FZB42 could establish itself successfully in the rhizosphere without showing any durable effect on the rhizosphere bacterial community.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus / drug effects
  • Bacillus / growth & development
  • Bacillus / physiology*
  • Colony Count, Microbial
  • Lettuce / growth & development*
  • Lettuce / microbiology*
  • Microbial Consortia*
  • Plant Diseases / microbiology
  • Plant Roots / microbiology
  • Polymorphism, Restriction Fragment Length
  • Rhizoctonia / drug effects
  • Rhizoctonia / physiology
  • Rhizosphere*
  • Rifampin / pharmacology
  • Software

Substances

  • Rifampin

Grant support

This work (part of the network “PATHCONTROL”) was funded by grants from Federal Ministry of Education and Research (BMBF) to Prof. Rainer Borriss (Grant 0315654A) and to Prof. Anton Hartmann (Grant 0315654C). No other external funding received. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.