Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2016
Publication Date: N/A
Technical Abstract: Pre-harvest contamination of maize (Zea mays L. ssp. mays) grain with aflatoxin is a chronic problem in the southeastern U.S. Aflatoxin is an FDA regulated carcinogenic mycotoxin produced by the fungus Aspergillus flavus (Link:Fr). A. flavus is a ubiquitous, saprophytic, soil-borne fungus capable of acting as an opportunistic ear-rot pathogen of maize during periods of drought and heat stress. Resistance to aflatoxin accumulation is heritable in maize, and resistant germplasm lines have been registered and released. These lines are derived from genetic backgrounds unadapted to temperate environments and were released as sources of resistance intended to serve as donor lines not as parental inbreds. However, all current sources of resistance are quantitative, which complicates conventional efforts to introgress resistance alleles from an unadapted donor to adapted but susceptible recipient lines. Mapping quantitative trait loci (QTL) and their linked markers enables the targeted introgression of the desired alleles via marker assisted backcrossing. This research aims to identify and map QTL in two aflatoxin accumulation resistant inbreds (Mp715 and Mp717) using a common susceptible parent (Va35). F2:3 mapping populations were developed from both crosses (Mp715xVa35 and Mp717xVa35). The Mp715xVa35 population was phenotyped for aflatoxin accumulation under artificial inoculation in replicated field trials in Starkville, MS in 2015. A second year of phenotyping will be conducted in 2016. The Mp717xVa35 population will be phenotyped similarly in 2016 and 2017. Genotyping with SNP and SSR markers and linkage map construction are underway for both populations. QTL in Mp715 and Mp717 were mapped previously using different susceptible parents (T173 and NC300, respectively), and Va35 was the susceptible parent in a QTL mapping study with Mp313E the resistant parent. Re-mapping Mp715 and Mp717 using Va35 will allow us to compare our findings with these earlier studies. Also, NILs have been created using Va35 as the recurrent parent and Mp313E as the donor parent. Mapping Mp715 and Mp717 by Va35 will facilitate the development of a set of NILs with a common background but different QTL, including NILs that pyramid resistance alleles from all three sources of resistance, allowing the effects of the QTL to be tested in novel combinations. These steps are necessary to validate the QTL once identified and to determine the most efficacious combinations thereof. This poster presents preliminary data from the early stages of this ongoing project.