Aflatoxin Project: The major goals of this project are to identify and characterize 60 new inbred lines displaying high and stable resistance to A. flavus and aflatoxin accumulation, and to identify and validate new genes and gene-based markers linked to these traits. Chromosome regions and genetic markers associated with resistance have been identified, and new lines, and test and back crosses developed. These lines have been shared with collaborators for further testing and development of lines for distribution to farmers.
a. 32 chromosomal regions associated with reduced aflatoxin levels have been identified and partially validated. Easy-to-use KASP SNP assays have been optimized for 22 of these to date and sent to CIMMYT and IITA and to interested maize breeders in other countries, for use in marker assisted introgression of resistance into locally adapted maize.
b. Testcrosses, backcrosses, and populations have been created with 60 resistant inbred lines (30 from CHPRRU, 15 from CIMMYT, and 15 from IITA). These lines have been sent to the other institutions and crossed to testers in each institute, thus creating hybrids (or backcrosses) between lines from each institution to expand available resistant lines for each institute. Crosses are being tested for yield and resistance to aflatoxin and local diseases at each institute.
c. An analysis pipeline for GWAS results of aflatoxin accumulation was used to analyze associations between genetic polymorphisms and aflatoxin levels and identified 17 pathways, most notably jasmonic acid production pathway, as the most significantly associated with aflatoxin resistance. This has uncovered major resistance mechanisms and many potential new resistance candidate genes.
d. 1242 hybrids from CIMMYT that are nearing release for distribution to farmers were tested for aflatoxin resistance in Kiboko, Kenya.
e. Jasmonic Acid identified as very important to aflatoxin resistance in maize. MLN screening opportunity opened up for western Africa. New hybrids between CIMMYT and IITA lines show not only aflatoxin resistance but also high yield and superior agronomic performance.