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Identification and Enhancement of Seed-Based Biochemical Resistance in Crops to Aflatoxin Producing Pathogens

  1. Identify new sources of corn germplasm resistant to fungal infection, growth, and aflatoxin contamination using laboratory and field inoculations of corn kernels with tester fungi designed for rapid resistance screening.
  2. Facilitate marker assisted corn breeding efforts. Identify resistance associated proteins (RAPs), e.g., antifungal, stress responsive, or interfering with toxin signaling pathways, in developing and mature corn kernels through proteomic comparisons of resistant and susceptible corn inbreds, some with very similar genetic backgrounds.
  3. Genetically engineer cotton with the resistant alleles of RAP genes from corn and also genes from non native sources to enhance resistance to aflatoxin contamination. Test genetically engineered crops in the greenhouse for resistance to aflatoxin contamination, and transfer selected resistant lines to cooperating plant breeders and plant pathologists for development of commercial or public varieties.
  4. Develop rapid, non destructive hyperspectral imaging methodology to measure fungal growth and aflatoxin in corn kernels and for assessing spectral signatures associated with traits for resistance to aflatoxin contamination.
Objectives 1-3 address utilization of resistance genes that could have generic value in enhancement of resistance in all crops vulnerable to aflatoxin contamination.
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Resistance to aflatoxin contamination will be enhanced in corn and cottonseed through marker assisted breeding and genetic engineering, respectively. In order to accomplish these goals, complex natural resistance mechanisms in corn kernels will be elucidated in resistant corn inbreds through identification of resistance associated proteins using proteomics and other resistance associated compounds through chemical analysis. Understanding the molecular basis of seed based resistances will lead to identification of biochemical factors correlated with resistance for use in marker assisted breeding and/or when pertinent resistance genes are identified and cloned, for use in enhancement of resistance in crops through genetic engineering. This strategy is especially pertinent to cottonseed, which does not possess practical levels of natural resistance to aflatoxin producing fungi in its germplasm base. Another goal is to assess resistance related biochemical products for their stability of expression in native and transgenic crops under environmental conditions (e.g. drought) known to be conducive to aflatoxin contamination. Also as a part of this project, rapid, non destructive detection methodology based upon hyperspectral imaging will be developed to exclude aflatoxin contaminated corn for enhancement of food safety and homeland security, and also to measure physical and biochemical attributes in kernels potentially useful in resistance marker selection.
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Bhatnagar, Deepak
Brown, Robert
Cary, Jeffrey
Klich, Maren
Rajasekaran, Kanniah
Yu, Jiujiang
Published Journal Articles USDA ARS (NP 108):
Expression of chloroperoxidase from Pseudomonas pyrrocinia in tobacco plastids for fungal resistance
Ruhlman TA, Rajasekaran K, Cary JW .
Plant Sci. 2014 Feb 26. [Epub ahead of print]
Food Safety Categories:
On-Farm Food Safety
Sanitation and Pathogen Control
Contaminants and Contamination