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Description of a novel aflatoxin-producing Aspergillus species from a region of the United States with perennial aflatoxin contamination
Pummi Singh: University of Arizona; Peter Cotty: USDA-ARS, University of Arizona
<div>Aflatoxins are potent carcinogens that contaminate a wide range of crops in warm regions, and are produced by several species in <i>Aspergillus </i>section <i>Flavi. </i>To completely describe the etiology of aflatoxin contamination<i>, </i>aflatoxin-producing species must be identified and characterized. During the course of molecular phylogenetic analysis of aflatoxin-producing fungi native to North America, a novel aflatoxin-producing species was identified. The new taxon was assigned the name <i>Aspergillus texensis</i>, P. Singh and P.J. Cotty, species novum. The new taxon has sclerotia production not differentiable from the <i>A. flavus </i>S strain morphotype<i>. </i>However<i>, A. texensis</i> produces both B and G aflatoxins whereas <i>A. flavus</i> produces only B aflatoxins. Total aflatoxins produced by isolates<i> of A. texensis</i> on maize did not differ (p > 0.05; mean = 172 ± 9.5 mg/kg) from quantities produced by the <i>A. flavus </i>S strain. <i>Aspergillus texensis</i> formed a highly supported monophyletic clade in phylogenies based on concatenated partial gene sequences of the beta-tubulin (0.5 kb), calmodulin (1.1 kb), and nitrate reductase (2.1 kb) genes. <i>Aspergillus texensis</i> is known from eleven isolates, nine from soils cropped to maize in Texas, where aflatoxin contamination of crops is a perennial issue, and one isolate each from maize grown in Arkansas and Louisiana. This is the first report of the occurrence in the United States of an S morphotype <i>Aspergillus </i>with ability to produce both B and G aflatoxins.</div>

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