Progress Toward a Novel Model System to Investigate Fungal Endophytic Suppression of Human Pathogens in Spinach
Abstract
Symbiotic microbes are known to benefit both human and plant hosts by influencing metabolic processes, immune defenses, and microbial colonization. Endophytic fungi are known to provide the host plant with benefits ranging from herbivore defense to enhanced immunity against phytopathogens. We have isolated the fungal endophytes Stemphylium PNW2016-02 and PNW2016-03 from commercial spinach tissue in an effort to characterize endophytic effects on plant health, including potential antimicrobial activity against the human pathogen E. coli O157:H7, a bacterial endophyte of spinach. Detection of Stemphylium in the tissue was aided by the development of a PCR-based detection method, amplifying the ITS region of the ribosomal RNA with subsequent SnaBI restriction enzyme digestion. Initial studies were aimed at assessing the colonization of spinach leaf tissue following Stemphylium inoculation onto pre-germinated spinach seeds. Following seed inoculation of our Stemphylium isolates, as measured by molecular detection, the fungus was shown to persist in the tissue over two weeks, at which point we observed a statistically significant enhancement of plant growth in PNW2016-02 individuals. This was surprising, as several Stemphylium species are known to be plant pathogens in plants including tomatoes, pears, and lentils. As previous studies demonstrated strong antimicrobial properties by PNW2016-02 in vitro, we hypothesize in plantae antimicrobial production could influence the composition of the endosphere microbial community. Future research is aimed at identifying microbial community changes during Stemphylium colonization in addition to in plantae E. coli competition assays. With a recent rise in plant-based enterohemorrhagic E. coli O157:H7 outbreaks, this work has the potential to influence the development of novel plant therapeutics through the use of endophytic fungi, and therefore impacts the fields of commercial agriculture and public health as a naturally derived substitute for preventative chemical treatments.
Degree
M.Sc.
Advisors
Bates, Purdue University.
Subject Area
Agriculture|Climate Change|Agricultural chemistry|Agronomy|Botany|Chemistry|Organic chemistry|Pathology|Pharmaceutical sciences|Plant Pathology|Plant sciences
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