Enhanced Resistance of Maize to Aspergillus flavus Infection, Aflatoxin Accumulation, and Insect Damage

<p>1. Identify new sources of maize germplasm with resistance to Aspergillus (A.) flavus infection and aflatoxin accumulation. We have developed and released maize germplasm lines with resistance to A. flavus infection and aflatoxin accumulation; however, germplasm with higher levels of resistance and different mechanisms of resistance are needed. We will evaluate germplasm obtained through the Germplasm Enhancement of Maize (GEM) project, the International Maize and Wheat Improvement Center (CIMMYT), and from other sources using methodologies developed in the research unit. Although we have developed effective procedures for inoculating plants with A. flavus and measuring aflatoxin, we will continue to evaluate other methods of quantifying resistance to increase efficiency and reduce costs. 2. Identify new sources of maize germplasm with resistance to fall armyworm, southwestern corn borer, and corn earworm. We have developed and released germplasm lines with excellent resistance to fall armyworm and southwestern corn borer leaf feeding damage using methodology for screening developed in the research unit. We will continue to screen germplasm from the GEM project, CIMMYT, and other sources to identify new sources of resistance to leaf feeding. We will also screen germplasm to identify sources of resistance to ear damage by fall armyworm, southwestern corn borer, and corn earworm. Because insect feeding provides a site for fungi to enter the developing ears of maize, resistance to ear-feeding insects should be reduced. 3. Develop and characterize genetic mapping populations, identify and elucidate functions of genes associated with resistance, and develop molecular markers for enhancing maize germplasm resistance to A. flavus/aflatoxin and insects. We have genotyped and phenotyped populations of F2:3 families to identify quantitative trait loci associated with resistance to aflatoxin accumulation and insect feeding, and additional populations are currently being developed. We have created near-isogenic lines (NILs) to validate the QTLs. We evaluated a 300-line association mapping panel for aflatoxin accumulation and ear damage by caused by insect feeding. From these studies we will identify and confirm additional QTL and candidate genes associated with resistance. We will investigate expression and function of these and other genes or groups of genes using a variety of techniques. 4. Develop and release maize germplasm with resistance to A. flavus infection, aflatoxin accumulation, and insect damage. Germplasm identified in Objectives 1 and 2 will be used in developing germplasm lines with resistance to aflatoxin accumulation and insect damage using conventional phenotypic selection. We will use information on molecular markers associated with resistance obtained from Objective 3 to enhance our efforts to produce better adapted lines with higher levels of pest resistance.</p>