Pre-harvest aflatoxin contamination is a major limitation to maize production in
Texas and the southern United States, causing major economic loss and severe health
problems worldwide. Screening for resistance to aflatoxin accumulation is commonly
conducted through inoculation with a highly concentrated solution of Aspergillus flavus
FR: Link spores, a naturally occurring fungus which infects maize and produces a toxic
metabolite (aflatoxin) to humans and animals consuming the grain. No commercial
hybrids exist with full resistance to aflatoxin accumulation; however, sources exist to
reduce susceptibility. These sources commonly lack good agronomic characteristics for
use in commercial hybrids. Exotic germplasm with favorable traits for reduced aflatoxin
accumulations are introgressed with temperate and locally adapted lines. This program
utilizes only one isolate of A. flavus even though many isolates exist in the environment.
The objectives of this thesis are i) to evaluate the progress of the Maize Breeding and
Genetics Program’s accomplishments of breeding maize for the reduction in
susceptibility of aflatoxin accumulation in yellow inbreds through analysis of hybrid and
inbred per se trials and ii) to determine whether interaction exists between geneticallydifferent
isolates of A. flavus and several genotypes of maize. Response to aflatoxin accumulation for hybrids and inbreds was measured at up to three environments across
Texas. Significant differences were detected for most years and environments. Maize
lines CML285, CML288, CML323, CML325, CML326, CML338, Tx601y and lines
derived from Population 69 and from Tx772 crosses in hybrid combinations tended to
accumulate less aflatoxin than commercial hybrid checks. Significant differences were
detected at each environment aflatoxin accumulation was measured for inbred lines per
se. Inbreds Tx772, Tx601y, CML289, CML294, CML323 and derived lines from
Population 69 show reduced aflatoxin accumulations. Interaction between genetically
different isolates of A. flavus and several genotypes of maize were not detected in hybrid
or inbred trials at two or three environments, across locations and across years.
Introgression of exotic germplasm into locally adapted germplasm has improved
agronomic characteristics for use in the Southern U.S. and brought sources for decreased
aflatoxin accumulation.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1184 |
| Date | 15 May 2009 |
| Creators | Mayfield, Kerry L. |
| Contributors | Betran, Javier |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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