Bacterial endophytes are being used as biocontrol organisms for the control of plant pathogens such as the corn fungal endophyte Fusarium verticillioides and its production of the fumonisin mycotoxins. It is our hypothesis that factors by which plant endophyte communities are regulated involve host-produced compounds that modify behavior of endophytic microbes, often reducing growth rates and suppressing pathogenic behaviors. These behavior-modifying compounds are proposed to include phenolic acids, quorum-quenching and -inhibiting compounds, and perhaps other secondary metabolites that are toxic and recorded as mycotoxins. There is a plethora of substances and structures peculiars to endophytes that inhabit plants that are interactive in protecting and regulating the success of endophytes. Biofilms are important indicator extracellular polymeric compounds produced by bacteria that are useful for developmental phases including motility, swarming, signaling processes, and for hydrophobic nutrient utilization, all of which are important attributes for biocontrol bacteria. As a start for the test of our hypothesis, an endophytic biocontrol bacterium, Bacillus mojavensis, was used as the model organism for the biocontrol used in corn for fumonisin reduction. A bank of biosensor bacteria were used to screen fungal, plant and bacteria for quorum sensing or inhibiting signals. Laser ablation electrospray ionization (LAESI) MS technology is a modern method that allows the in situ cell imaging of tissues, resulting in a noninvasive measure and chemical analyses of microbes and hosts parasitic interactions to test for such interactions. LAESI MS was use to determine biofilm production relative to specific biosurfactants, other metabolites for antagonisms to the maize pathogen F. verticillioides and its fumonisin mycotoxins. Results are presented and characterized according to the reaction of the producing organisms, fungus or bacterium, and an interaction to the plant that should lead to information useful for field-testing of bacteria and their requirement for success in reducing the ubiquitous presence of F. verticillioides in corn.

New strategy for the biocontrol of Fusarium verticillioides in corn based on endophytic bacterial-fungal interactions

251st National Meeting (2016)

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