| Sumario: | Abstract Maize streak virus (MSV) disease is a devastating
disease in the Sub-Saharan Africa (SSA), which causes
significant yield loss in maize. Resistance to MSV has
previously been mapped to a major QTL (Msv1) on chromosome
1 that is germplasm and environment independent
and to several minor loci elsewhere in the genome.
In this study, Msv1 was fine-mapped through QTL isogenic
recombinant strategy using a large F2 population of
CML206 × CML312 to an interval of 0.87 cM on chromosome
1. Genome-wide association study was conducted in
the DTMA (Drought Tolerant Maize for Africa)-Association
mapping panel with 278 tropical/sub-tropical breedinglines from CIMMYT using the high-density genotypingby-
sequencing (GBS) markers. This study identified 19
SNPs in the region between 82 and 93 Mb on chromosome
1(B73 RefGen_V2) at a P < 1.00E-04, which coincided
with the fine-mapped region of Msv1. Haplotype trend
regression identified a haplotype block significantly associated
with response to MSV. Three SNPs in this haplotype
block at 87 Mb on chromosome 1 had an accuracy of 0.94
in predicting the disease reaction in a collection of breeding
lines with known responses to MSV infection. In two
biparental populations, selection for resistant Msv1 haplotype
demonstrated a reduction of 1.03–1.39 units on a rating
scale of 1–5, compared to the susceptible haplotype.
High-throughput KASP assays have been developed for
these three SNPs to enable routine marker screening in the
breeding pipeline for MSV resistanceAbstract Maize streak virus (MSV) disease is a devastating
disease in the Sub-Saharan Africa (SSA), which causes
significant yield loss in maize. Resistance to MSV has
previously been mapped to a major QTL (Msv1) on chromosome
1 that is germplasm and environment independent
and to several minor loci elsewhere in the genome.
In this study, Msv1 was fine-mapped through QTL isogenic
recombinant strategy using a large F2 population of
CML206 × CML312 to an interval of 0.87 cM on chromosome
1. Genome-wide association study was conducted in
the DTMA (Drought Tolerant Maize for Africa)-Association
mapping panel with 278 tropical/sub-tropical breedinglines from CIMMYT using the high-density genotypingby-
sequencing (GBS) markers. This study identified 19
SNPs in the region between 82 and 93 Mb on chromosome
1(B73 RefGen_V2) at a P < 1.00E-04, which coincided
with the fine-mapped region of Msv1. Haplotype trend
regression identified a haplotype block significantly associated
with response to MSV. Three SNPs in this haplotype
block at 87 Mb on chromosome 1 had an accuracy of 0.94
in predicting the disease reaction in a collection of breeding
lines with known responses to MSV infection. In two
biparental populations, selection for resistant Msv1 haplotype
demonstrated a reduction of 1.03–1.39 units on a rating
scale of 1–5, compared to the susceptible haplotype.
High-throughput KASP assays have been developed for
these three SNPs to enable routine marker screening in the
breeding pipeline for MSV resistance
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