Enhancing Corn with Resistance to Aflatoxin Contamination and Insect Damage

Title:	Enhancing Corn with Resistance to Aflatoxin Contamination and Insect Damage
Objective:	Identify and develop corn germplasm with resistance to Aspergillus flavus infection/aflatoxin contamination and ear-feeding insects and release this germplasm together with information on molecular markers and methodology that will expedite its deployment into commercially available corn hybrids. Specific objectives include the following: Determine the effects of indigenous fungal species and ear-feeding insects on A. flavus infection and aflatoxin accumulation in corn grain; Identify new sources of corn germplasm with resistance to A. flavus infection and aflatoxin accumulation and/or resistance to damage by southwestern corn borer, fall armyworm, and corn earworm; Identify quantitative trait loci, genes, and proteins associated with resistance in corn to A. flavus infection, aflatoxin accumulation, and insect damage; Enhance corn germplasm with resistance to A. flavus infection, aflatoxin accumulation, and insect damage and release germplasm lines as sources of resistance.
More Info:	Approach: Objective 1. Determine the effects of indigenous fungal species and ear-feeding insects on A. flavus infection and aflatoxin accumulation in corn grain. Colonization of corn grain is rarely by a single fungal species, but rather a mixture of fungi. Fusarium verticillioides (syn. F. moniliforme) is the most commonly reported fungus infecting corn in the USA, and it is frequently found together with A. flavus. Acremonium zeae is a common contaminant of preharvest corn in the Southeast. It has been reported to suppress growth of both A. flavus and F. verticillioides in laboratory experiments. The interactions of these fungi will be investigated to determine whether F. verticillioides and A. zeae affect A. flavus infection of corn grain and the subsequent accumulation of aflatoxin, and if so, whether these fungi are impediments to the identification of aflatoxin-resistant corn germplasm. The association between insect damage and aflatoxin accumulation in different corn genotypes will be investigated and the extent to which resistance to damage by southwestern corn borer, Diatraea grandiosella; fall armyworm, Spodoptera frugiperda; or corn earworm, Helicoverpa zea, reduces aflatoxin contamination will be determined. Objective 2. Identify new sources of corn germplasm with resistance to A. flavus infection and aflatoxin accumulation and/or resistance to damage by southwestern corn borer, fall armyworm, and corn earworm. Corn germplasm from diverse backgrounds will be screened for resistance to A. flavus/aflatoxin, southwestern corn borer, fall armyworm, and corn earworm. Information on the effects of other fungi or insects on A. flavus/aflatoxin accumulation (Objective 1) will be used to refine and improve techniques for evaluating germplasm for resistance. Newly identified sources of resistance will be used to pursue Objectives 3 and 4. Objective 3. Identify quantitative trait loci, genes, and proteins associated with resistance in corn to A. flavus infection, aflatoxin accumulation, and insect damage. Populations of F2:3 families and recombinant inbred lines derived from crosses between aflatoxin or insect resistant inbred lines and susceptible lines will be used to identify quantitative trait loci (QTL) associated with resistance. Resistant and susceptible corn inbred lines and recombinant inbred lines will be used in complementary investigations to identify candidate genes and proteins associated resistance. Molecular markers identified in these investigations will be used in developing improved germplasm lines (Objective 4). Objective 4. Enhance corn germplasm with resistance to A. flavus infection, aflatoxin accumulation, and insect damage and release germplasm lines as sources of resistance. Both breeding methods based on phenotypic performance and those based on molecular markers will be used to enhance germplasm with resistance to aflatoxin contamination and insect damage. The effectiveness of molecular markers based on QTL, genes, and proteins identified in Objective 3 in transferring resistance to A. flavus/aflatoxin and insect damage into germplasm lines with desirable agronomic qualities will be determined.
Funding Source:	United States Department of Agriculture (USDA), Agricultural Research Service (ARS)
Type:	USDA Inhouse
Start Date:	2008
End Date:	2013
Project Number:	6406-21000-011-00
Accession Number:	0412885
Institutions:	USDA/ARS - Mid South Area
Investigators:	Hawkins, Leigh Henry, Brien Williams, William Windham, William
Pending USDA ARS Publications (NP 108):	The maize rachis affects Aspergillus flavus movement during ear development
Published USDA ARS Articles (NP 108):	A two-dimenstional proteome reference map of the aflatoxigenic fungus Aspergillus flavus Pechanova O, Pechan T, Rodriguez J, Williams WP, Brown A. Proteomics. 2013 May;13(9):1513–8. Confirming QTL for aflatoxin resistance from Mp313E in different genetic backgrounds Willcox M, Davis G, Warburton ML, Windham GL, Abbas HK, Betran J, Holland JB, Williams WP. Mol Breed. 2013 Apr 9. [Epub ahead of print] Natural variation in the sequence of PSY1 and frequency of favorable polymorphisms among tropical and temperate maize germplasm Fu Z, Chai Y, Zhou Y, Yang X, Warburton ML, Xu S, Cai Y, Zhang D, Li J, Yan J. Theor Appl Genet. 2013 Apr;126(4):923-35.
Publications:	View related publications.
Food Safety Categories:	On-Farm Food Safety Contaminants and Contamination Pathogen Biology Plant Science & Plant Products
Farm-to-Table categories:	On-farm food production

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Title:

Objective:

Identify and develop corn germplasm with resistance to Aspergillus flavus infection/aflatoxin contamination and ear-feeding insects and release this germplasm together with information on molecular markers and methodology that will expedite its deployment into commercially available corn hybrids.

Specific objectives include the following:

Determine the effects of indigenous fungal species and ear-feeding insects on A. flavus infection and aflatoxin accumulation in corn grain;
Identify new sources of corn germplasm with resistance to A. flavus infection and aflatoxin accumulation and/or resistance to damage by southwestern corn borer, fall armyworm, and corn earworm;
Identify quantitative trait loci, genes, and proteins associated with resistance in corn to A. flavus infection, aflatoxin accumulation, and insect damage;
Enhance corn germplasm with resistance to A. flavus infection, aflatoxin accumulation, and insect damage and release germplasm lines as sources of resistance.

More Info:

Approach:
Objective 1. Determine the effects of indigenous fungal species and ear-feeding insects on A. flavus infection and aflatoxin accumulation in corn grain. Colonization of corn grain is rarely by a single fungal species, but rather a mixture of fungi. Fusarium verticillioides (syn. F. moniliforme) is the most commonly reported fungus infecting corn in the USA, and it is frequently found together with A. flavus. Acremonium zeae is a common contaminant of preharvest corn in the Southeast. It has been reported to suppress growth of both A. flavus and F. verticillioides in laboratory experiments. The interactions of these fungi will be investigated to determine whether F. verticillioides and A. zeae affect A. flavus infection of corn grain and the subsequent accumulation of aflatoxin, and if so, whether these fungi are impediments to the identification of aflatoxin-resistant corn germplasm. The association between insect damage and aflatoxin accumulation in different corn genotypes will be investigated and the extent to which resistance to damage by southwestern corn borer, Diatraea grandiosella; fall armyworm, Spodoptera frugiperda; or corn earworm, Helicoverpa zea, reduces aflatoxin contamination will be determined.

Objective 2. Identify new sources of corn germplasm with resistance to A. flavus infection and aflatoxin accumulation and/or resistance to damage by southwestern corn borer, fall armyworm, and corn earworm. Corn germplasm from diverse backgrounds will be screened for resistance to A. flavus/aflatoxin, southwestern corn borer, fall armyworm, and corn earworm. Information on the effects of other fungi or insects on A. flavus/aflatoxin accumulation (Objective 1) will be used to refine and improve techniques for evaluating germplasm for resistance. Newly identified sources of resistance will be used to pursue Objectives 3 and 4.

Objective 3. Identify quantitative trait loci, genes, and proteins associated with resistance in corn to A. flavus infection, aflatoxin accumulation, and insect damage. Populations of F2:3 families and recombinant inbred lines derived from crosses between aflatoxin or insect resistant inbred lines and susceptible lines will be used to identify quantitative trait loci (QTL) associated with resistance. Resistant and susceptible corn inbred lines and recombinant inbred lines will be used in complementary investigations to identify candidate genes and proteins associated resistance. Molecular markers identified in these investigations will be used in developing improved germplasm lines (Objective 4).

Objective 4. Enhance corn germplasm with resistance to A. flavus infection, aflatoxin accumulation, and insect damage and release germplasm lines as sources of resistance. Both breeding methods based on phenotypic performance and those based on molecular markers will be used to enhance germplasm with resistance to aflatoxin contamination and insect damage. The effectiveness of molecular markers based on QTL, genes, and proteins identified in Objective 3 in transferring resistance to A. flavus/aflatoxin and insect damage into germplasm lines with desirable agronomic qualities will be determined.

Funding Source:

United States Department of Agriculture (USDA), Agricultural Research Service (ARS)

Type:

USDA Inhouse

Start Date:

2008

End Date:

2013

Project Number:

6406-21000-011-00

Accession Number:

0412885