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Title: Microbial Endophytes of Corn

item Glenn, Anthony - Tony

Submitted to: Corn Dry Milling Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/18/2009
Publication Date: 6/18/2009
Citation: Glenn, A.E. 2009. Microbial Endophytes of Corn. Corn Dry Milling Conference Proceedings. June 18, 2009. Peoria, IL.

Interpretive Summary: Abstract - no summary required

Technical Abstract: Increasing recognition is being given to the impact of microbial population dynamics on the general health of biological systems. Building on previous mycological and bacteriological research on agricultural commodities, more advanced technology is expanding our understanding of the “endophytic habit”. Endophytes are symbiotic, physiologically active fungi or bacteria living within plant tissues, typically in intercellular spaces. Most if not all of the life cycle of these microbes may occur within the plant, and colonization can by either systemic or distinctly localized to certain tissues, depending on the plant-microbe association. Some endophytes are mutualistic while others are facultative pathogens. Long-term host associations may occur, including seed transmission. Overall, endophytic microbes can be ecologically and physiologically relevant to plant fitness and productivity. The endophytic microbial community within corn plants can vary depending on geographical regions and environmental factors. Dominant fungal endophytes of corn include species of Fusarium, Acremonium, Trichoderma, and Nigrospora. Of these, Fusarium species are of primary importance due to their production of several mycotoxins. Fusarium verticillioides is notable for its production of the fumonisins. Endophytic infection by F. verticillioides has no obvious benefit to the corn plant, yet the association is ubiquitous throughout corn production regions. While symptomless infections are common, the fungus is capable of causing ear rot and other disease symptoms. Plant infections can occur through seed transmission (vertical) as well as spore dispersal (horizontal), with most kernel infections occurring via horizontally dispersed spores that land on young silks. While contamination of corn with fumonisins is of concern for food and feed safety, fumonisins also may impact the development of corn plants, with significant effects on root growth. Additional host-pathogen interactions will be discussed, including how production of antimicrobial compounds by corn may impact the overall fungal endophyte community structure and favor infections by F. verticillioides.