Niche Overlap Index (NOI) and antibiosis: Consistent and reliable procedures for selecting bacteria as biocontrol agents at root level

CAVAGLIERI L.R; MAGNOLI C.E; ETCHEVERRY M.G

Prospects and Applications for Plant Associated Microbes, A laboratory manual, Part A: Bacteria

BBi. Printing house:

Lugar: Karhukopio, Turku, Finland; Año: 2008; p. 126 - 303

Microorganisms establish interactions with plant roots that are environmentally influenced. Understanding their ecological role is important because they play a key role in agricultural environments and are promising for their potential use in sustainable agriculture as biocontrol agents. The use of microorganisms that are well adapted to the host plant and well established to the root system could have a practical value in the control of soil-borne pathogens at the root level. Effective bacteria can be selected through adequate procedures. Screening is a critical step in the development of biocontrol agents. The success of all subsequent stages depends on the ability of the screening procedure to identify an appropriate candidate able to develop different competitive strategies on the pathogen, such us growth rate decrease, lag phase increase, decrease in toxin production and less competence in utilization of carbon sources. Niche overlap index (NOI) and antibiosis are consistent and reliable procedures for selecting effective bacteria as biocontrol agents able to reduce fungal root colonization and mycotoxin production. Bacteria first selected by NOI and used for fungal repression assays (at an appropriate inoculum size) demonstrated a positive correlation between the in vitro antibiosis assay and greenhouse conditions. The application of this methodology shows a way to outline the best biocontrol candidates or mixtures to be applied against fungal pathogens at the root level.