Supplemental files from the study: A genome-wide association study to understand the effect of Fusarium verticillioides infection on seedlings of a maize diversity panel
Fusarium
verticillioides, which causes ear, kernel and stem rots, has
been reported as the most prevalent species on maize worldwide. Kernel infection by F. verticillioides
results in reduced grain yield and quality as well as fumonisin contamination,
and may affect seedling traits like germination rate, entire plant seedling
length and weight. Maize resistance to Fusarium
is a quantitative and complex trait controlled by numerous genes with small
effects. In the present work, a Genome Wide Association Study (GWAS) of traits
related to Fusarium seedling rot was carried out in 230 lines of a maize association
population using 226,446 SNP markers. Phenotypes were scored on artificially
infected kernels applying the rolled towel assay screening method and three
traits related to disease response were measured in inoculated and
not-inoculated seedlings: plant seedling length (PL), plant seedling weight (PW)
and germination rate (GERM). Overall, GWAS resulted in 42 SNPs significantly
associated with the examined traits. Two and eleven SNPs were associated with PL
in inoculated and not-inoculated samples, respectively. Additionally, six and one
SNPs were associated with PW and GERM traits in not-inoculated kernels, and
further nine and thirteen SNPs were associated to the same traits in inoculated
kernels. Five genes containing the significant SNPs or physically closed to
them were proposed for Fusarium
resistance, and 18 out of 25 genes containing or
adjacent to significant SNPs identified by GWAS in the current research
co-localized within QTL regions previously reported for resistance to Fusarium seed
rot, Fusarium ear rot and fumonisin accumulation. Furthermore, linkage
disequilibrium analysis revealed an additional gene not directly observed by
GWAS analysis. These findings could aid to better understand the complex
interaction between maize and F. verticillioides.