Location: Corn Host Plant Resistance Research
Project Number: 6064-21000-018-000-D
Project Type: In-House Appropriated
Start Date: Feb 8, 2023
End Date: Feb 7, 2028
1. Identify maize germplasm with resistance to Aspergillus flavus infection, aflatoxin accumulation, and fall armyworm damage. 1.A. Evaluate maize germplasm to (1) identify the most promising lines to use as donor and recurrent parents in breeding populations that will combine resistance to aflatoxin accumulation with improved agronomic traits and (2) identify new sources of resistance to Aspergillus flavus infection and aflatoxin accumulation. 1.B. Identify promising maize germplasm lines to use in breeding crosses and populations to develop well-adapted inbred lines with high levels of resistance to fall armyworm feeding and new sources of resistance to fall armyworm damage. 2. Identify molecular markers associated with resistance to aflatoxin accumulation and fall armyworm damage, and determine their utility in marker-assisted selection for these traits. 2.A. Validate QTL for their utility in marker-assisted breeding for increased resistance to aflatoxin accumulation and fall armyworm damage. 2.B. Map QTL for resistance to aflatoxin accumulation using multi-parent mapping strategies and identify molecular markers associated with those QTL for use in marker-assisted breeding. 3. Identify biotic and abiotic factors associated with increased accumulation of aflatoxin in maize grain and evaluate effectiveness of resistance to aflatoxin accumulation under stress conditions. 3.A. Determine the effects of fall armyworm and southwestern corn borer infestations on Aspergillus ear rot and aflatoxin accumulation in maize hybrids with different levels of insect resistance. 3.B. Evaluate the effect of the interaction between genotype and planting density on mycotoxin contamination, ear-rot and related traits. 4. Develop and release adapted, stress tolerant maize inbred lines with desirable agronomic qualities and resistance to aflatoxin accumulation or fall armyworm damage. 4.A. Answer key questions regarding breeding methodology for the development of adapted maize germplasm with resistance to aflatoxin accumulation. 4.B. Develop well adapted inbred lines that combine high levels of resistance to aflatoxin accumulation and Aspergillus ear-rot with improved agronomic traits and tolerance to key abiotic and biotic stresses that impact aflatoxin accumulation in maize. 4.C. Develop maize germplasm lines with resistance to fall armyworm damage and desirable agronomic qualities.
Genetic Improvement of Maize for Resistance to Aflatoxin Accumulation and Fall Armyworm Damage is the main emphasis of this research project. Aspergillus (A.) flavus, a common pathogen of maize globally, is especially problematic in the southeastern U.S. It causes ear-rot and contaminates grain with aflatoxin, a highly carcinogenic mycotoxin. Susceptibility to aflatoxin accumulation is increased by insect damage and such abiotic stresses as heat and drought. Maize genotypes with resistance to A. flavus infection and aflatoxin accumulation can reduce losses to aflatoxin contamination. Resistant genotypes have been identified, but further work is necessary to leverage this genetic material. Conventional breeding will be used to develop lines with disease resistance, improved agronomic traits, and tolerance to the abiotic stresses associated with aflatoxin contamination. Molecular analysis will identify markers and genes associated with disease resistance. These markers will allow efficient introgression of disease resistance from donor lines to elite inbred lines with superior agronomic qualities. Disease screening will identify new sources of resistance. Combining disease resistance, abiotic stress tolerance, improved agronomics, and insect resistance will be undertaken in this project. Fall armyworm (Spodoptera frugiperda), a particularly important insect pest of maize in the southeastern U.S., has spread globally in recent years becoming a major threat to maize production worldwide. This unit has developed many lines with outstanding resistance to fall armyworm leaf-feeding. Conventional breeding, molecular mapping, and molecular analysis will be used to exploit the resistance in this germplasm. Additional germplasm will be evaluated to identify new sources of resistance to fall armyworm leaf and ear feeding. Germplasm developed in this project, accompanying information on methodologies, and associated markers will be made available to researchers who develop disease and insect resistant and stress resilient maize hybrids. Four major approaches (objectives) will be used in this project; 1) Identify maize germplasm with resistance to Aspergillus flavus infection, aflatoxin accumulation, and fall armyworm damage; 2) Identify molecular markers associated with resistance to aflatoxin accumulation and fall armyworm damage, and determine their utility in marker-assisted selection for these traits; 3) Identify biotic and abiotic factors associated with increased accumulation of aflatoxin in maize grain and evaluate effectiveness of resistance to aflatoxin accumulation under stress conditions; 4) Develop and release adapted, stress tolerant maize inbred lines with desirable agronomic qualities and resistance to aflatoxin accumulation or fall armyworm damage.