Creation and Mapping of a New Mapping Population to Identify NOVEL Qtls for Aflatoxin Accumulation Resistance in Maize.

CREATION AND MAPPING OF A NEW MAPPING POPULATION TO IDENTIFY NOVEL QTLS FOR AFLATOXIN ACCUMULATION RESISTANCE IN MAIZE Oluwaseun F. Ogunola1, Marilyn L. Warburton2, W. Paul Williams2, Wenwei Xu3 1Department of Plant and Soil Sciences, Mississippi State University, Mississippi State, MS, USA. 2USDA Corn Host Plant Resistance Research Unit, Mississippi State University, Mississippi State, MS, USA. 3Department of soil and crop sciences, Texas A&M Agrilife Research, Lubbock, TX, USA. Aflatoxin is a secondary carcinogenic metabolite produced by Aspergillus flavus (Link:Fr) under favorable environmental conditions such as the hot and humid environments experienced annually in the Southern U.S and other countries. Aflatoxin accumulation in maize and other crops causes economic hardship to farmers and poses serious health issues in developing countries that lack the infrastructure for proper grain testing. Host plant resistance is the most efficient method of reducing aflatoxin accumulation in maize. Identification of maize (Zea mays L.) germplasm with resistance to aflatoxin accumulation is the first step in breeding for resistance. However, the quantitative nature of the trait makes it hard to transfer from resistant donor lines into elite cultivars. The use of molecular markers linked to quantitative trait loci (QTL) for resistance is one way to hasten this task, and some QTL have been identified to date. To identify novel QTL in a newly identified resistant maize line, a mapping population consisting of 238 F2:3 families was developed from CML69, an aflatoxin resistant inbred line from the Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT) and Va35, an aflatoxin susceptible inbred line adapted to the southern US. A total of 180 single nucleotide polymorphisms (SNP) markers spanning all 10 chromosomes in the maize genome was tested on the new QTL mapping population. Aflatoxin levels for each family were also determined in replicated field trials in four different locations. Results show that 72 SNP markers tested were polymorphic between the parents and were screened on all 238 families to create the initial genetic linkage map. These SNPs were mapped using the Joinmap software. Composite interval mapping (CIM) was carried out using the QTL cartographer to estimate the effect of each QTL on aflatoxin accumulation resistance. QTL results are presented here.