Author
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Yates, Ida |
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JAWORSKI, A. - BOTANY, U GEORGIA, ATHENS |
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Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/31/2000 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. Humans and animals eating corn products containing these toxins develop serious, and often fatal, health problems. We need to understand when, where, and how this fungus grows with corn if we are to develop a means to reduce toxin levels in our food supply. The objective of our studies was to determine which surface parts of the corn plant support growth of F. moniliforme. F. moniliforme was inoculated onto different corn plant parts, including roots, stems, leaves, pollen, as well as immature and mature kernels. Researchers at Russell Research Center discovered that F. moniliforme growth was sparse on roots, stems, leaves and undamaged, mature dry kernel coat. In contrast, growth was abundant on pollen, immature kernels, and damaged seed coats of the mature dry kernel. The importance of these studies is that certain parts of the corn plant possess characters restricting growth of the fungus. Thus, control strategies should be targeted to the most susceptible parts of the corn plant, pollen and immature kernels. Technical Abstract: Vegetative and reproductive tissues of corn, Zea mays, were inoculated in vitro with Fusarium moniliforme to analyze the initial stages of colonization. The F. moniliforme isolate was tagged with a reporter gene providing unequivocal evidence that developing mycelia were from the inoculum source, excluding possibilities of an external contaminant or an internal endophytic F. moniliforme. Vegetative tissues were dissected from roots, stems, and leaves; and reproductive tissues, from developing male and female inflorescence and fruits. In addition, conidial development was analyzed on artificial substrates and mature kernels. F. moniliforme colonized vegetative tissues more rapidly and extensively than reproductive tissues. F. moniliforme conidia inoculated on immature kernels formed a dense mycelial mat; whereas, F. moniliforme conidia inoculated on mature kernels developed sparse hyphae, unless the kernels were wounded. Thus, tissue type, age, and physical condition of the plant tissues are factors responsible for differences of in vitro colonization. F. moniliforme conidia placed on glass coverslips germinated, developed branched hyphae, and produced spores at >95% RH, but not at <5% RH, demonstrating independence of external nutrient sources or signals, except appropriate hydration, in order to propagate more conidia. |
