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ARS Home » Research » Publications at this Location » Publication #81870


item Yates, Ida
item Hiett, Kelli
item SMART, W
item Glenn, Anthony - Tony
item Hinton, Dorothy
item Bacon, Charles
item Meinersmann, Richard - Rick
item LIU, S

Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Food safety is a problem in corn products contaminated by toxins produced by Fusarium moniliforme, a fungus. Many times this fungus grows in the corn plant and causes no visible disease. We need to understand when, where, and how this fungus grows within corn if we are to develop a means to reduce toxin levels in our food supply. However, there are no techniques for precise tracking of the fungus in the plant. The objective of our investigation was to tag F. moniliforme with an easily detectable marker to provide a direct system for monitoring the course of corn infection. With genetic engineering, researchers at Russell Research Center were able to insert a gene into F. moniliforme which can be easily detected by staining and confirmed by molecular biology techniques. The importance of these studies is in developing tools for determining the conditions of plant growth, such as photoperiod, stress, and age that promote and/or hinder F. moniliforme colonization.

Technical Abstract: Visual markers detectable by histochemical staining have been developed for analyzing the time course specificity of corn infections by the fungal endophyte, Fusarium moniliforme. Three F. moniliforme strains, RRC 374, MRC 826, and RRC PAT, were transformed with a plasmid, pHPG, containing the gusA reporter gene which codes for beta-glucuronidase (GUS) and the hph gene for hygromycin resistance as the selectable marker. Germinating conidia used as the vector for the plasmid resulted in a 1.2 x 10(to the -7)transformants/conidium; however, expression of both gusA and hph was transient. Transformants using photoplasts as the vector were even more infrequent, but stable transformants were obtained. Southern blot and PCR analyses confirmed incorporation of pHPG into the genome of all three F. Moniliforme strains with gusA properly inserted in MRC 826 and RRC PAT, but apparently disrupted in RRC 374. The growth pattern for transformed F. moniliforme isolates and the parental wild types followed a sigmoid curve on minimal and enriched media. Hygromycin totally inhibited growth for wild type isolates, but no of transformants. Transformed isolates maintained their ability to infect the corn plant.