ARS | Publication request: MOLECULAR GENETIC APPROACHES FOR MEASURING MICROBIAL DIVERSITY: EXAMPLES FROM FILAMENTOUS FUNGI

Submitted to: Diversity and Use of Agricultural Microorganisms
Publication Type: Book / Chapter
Publication Acceptance Date: April 1, 1999
Publication Date: N/A

Interpretive Summary: This paper represents a brief review of how molecular biological techniques are transforming the ability of scientists to detect and identify beneficial and harmful microorganisms. One of the most powerful techniques to emerge within the past 10 years, called the polymerase chain reaction (abbreviated PCR), now makes it possible to make small copies of the genetic material or DNA of any microbe in a test tube. Once synthesized, the letter-for-letter genetic alphabet of these pieces of DNA can be read precisely using automated instrumentation available only within the past 5 years. Molecular analyses, using this technology, have made it possible to accurately examine the host range and geographic distribution of plant pathogens within the toxin-producing filamentous fungus Fusarium for the first time. Knowledge gained from these studies is essential for assessing the impact of these molds and their toxins on food safety and human and animal health.

Technical Abstract: This paper presents an overview of how molecular genetic techniques are transforming our ability to identify and classify microorganisms at all taxonomic levels. Special focus is directed at how the polymerase chain reaction (PCR) combined with automated DNA sequencing are providing systematists with a wealth of discrete characters upon which an objective, phylogenetically-based system of classification of microorganisms can be constructed. Specific examples of how these techniques have advanced our knowledge of the species biology and biogeography of several agronomically important genera of filamentous fungi are drawn from recent studies of the mycotoxigenic and phytopathogenic genus Fusarium including the 'bakanae' pathogen of rice, Gibberella fujikuroi; the koji Aspergillus molds used in fermented food such as soy sauce, miso and sake; the genetic diversity of shiitake mushrooms in Asia; and the edible true morels of the genus Morchella in the northern hemisphere.