abstr: Visualization Aspergillus mycotoxins

Nancy Keller npk3325 at VENUS.TAMU.EDU
Tue Aug 30 11:29:01 EST 1994

Keller N P, Butchko R, Sarr A, Phillips T 1994. A visual pattern of
mycotoxin production in maize kernels by Aspergillus  spp.  Phytopathology.

Different Aspergillus species (flavus, parasiticus and nidulans) which
produce different intermediates and end-products of the aflatoxin pathway
(norsolorinic acid, NOR; sterigmatocystin, ST and aflatoxin, AF) are useful
in studying the maize/Aspergillus/mycotoxin interaction.  Aspergillus AF
mutants which produce NOR, a visible orange intermediate of both ST and AF,
were used to visualize mycotoxin deposition in host and fungal tissues. 
NOR was seen in specific maize kernel tissues (embryo and aleurone) and
specific fungal tissues (substrate mycelium and not sporulating mycelium)
within 24 hours after inoculation of kernels or growth media.  ST and AF
were found in the same maize tissues but only after quantitating organic
extracts of these tissues using time consuming chromotography
methodologies.  Mycotoxin production and fungal ingress by all three
Aspergillus spp. was subject to regulation by the developmental stage of
the maize kernel:  both fungal colonization and NOR deposition shifts from
embryonic to endosperm tissues in germinating maize kernels.  The
appearance of NOR flagged the progress of fungal invasion through kernel
tissues.  We suggest that NOR mutants may be useful tools to identify
likely infection sites in maize kernels and that the genetically
characterized A. nidulans may be useful in helping identify global
regulatory mechanisms in the maize/Aspergillus/mycotoxin interaction.
Nancy P. Keller
Dept. Plant Pathology and Microbiology
Texas A&M University
College Station, TX 77843-2132
409-845-0963 P
409-845-8463 F
npk3325 at venus.tamu.edu

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