Quorum quenchers and sensors as possible roles for mycotoxins and other secondary metabolites of fungi

Authors: Bacon, Charles; Hinton, Dorothy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/6/2016
Publication Date: 6/6/2016
Citation: Bacon, C.W., Hinton, D.M. 2016. Quorum quenchers and sensors as possible roles for mycotoxins and other secondary metabolites of fungi. Corn Utilization & Technology Conference, June6-8, 2016, St.Louis Missouri

Interpretive Summary:

Technical Abstract: The assumed role for mycotoxins is to act as defensive metabolites thus serving as protection for fungi from biotic antagonisms and as such do not interact with the daily metabolic requirements of the producing fungus. Preventive strategies are devoted to reducing the accumulation of mycotoxins based on this assumption without regards to any molecular approaches based on their function at the organismal level. We feel that in addition to this, we should also determine the role of such metabolites to develop control measures of fungi and in particular, any biocontrol species and this specifically applies to those fungi with the endophytic and biotrophic life style. In this regards, much attention is directed to the control of 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 involves both a sensing mechanism and 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 coincidentally as toxic and recorded as mycotoxins. A variety of endophytic substances inhabits the plant responses to colonizing that are interactive in regulating the success of endophytes. The reverse is equally true, although in most instances the fungus components nullifies the plant substance. As regulators, quorum compounds control various important developmental phases of competing microorganisms and plant hosts such as reduction in yield, signaling processes, and hydrophobic nutrient utilization. Such interactions would indicate roles of mycotoxins beyond those of primary antagonist and redefine roles as multiple regulators of host genes and any competing microorganism. The objective of this study is to determine the specific activity of mycotoxins as quorum sensing or quorum quenching compounds. Our hypothesis is that certain mycotoxins are capable of controlling and sensing signals within association that served to benefit or inhibit the producing organism. As a test for our hypothesis, we report here on the use of a bank of quorum biosensor bacteria as a screen for mycotoxins for quorum sensing or inhibiting signals in corn, and the fumonisin producing fungus F. verticillioides. We tested quorum functions of the fumonisins, the aflatoxins, citrinin, fusaric acid, ochratoxins, zearalanone, zearalenone, penicillic acid, and T2-toxin. Results are presented and characterized according to the reaction a quorum quencher or signal along with and a competing endophytic biocontrol bacterium. Such studies should lead to a more targeted genetic methods of control, and lead to information useful for field-testing of biocontrol organisms and their requirement for success in reducing the ubiquitous presence of F. verticillioides and other mycotoxic fungi in corn.