Association Mapping of Resistance to Yellow Rust in Winter Wheat Cultivars and Elite Genotypes

Yellow (stripe) rust, caused by Puccinia striiformis
f.sp. tritici (Pst), is a destructive disease of
wheat (Triticum aestivum L.) all over the world,
particularly in the Central and West Asia and
North Africa (CWANA) region. Host plant resistance
is the most economical and environment
friendly approach to combating wheat rusts
through the deployment of resistant cultivars. In
this study, we report findings from an association
mapping (AM) study of resistance to Pst in
167 facultative/winter elite wheat genotypes. The
genotypes were evaluated for resistance to yellow
rust (YR) at the adult plant stage and other
agronomic traits for 2 yr (2011–2012) at ICARDA
field station, Tel Hadya, Syria. The same genotypes
were genotyped using 3051 diversity array
technology (DArT) markers of which 1586 were
of known chromosome positions. Out of the 167
genotypes evaluated for YR resistance, 65 genotypes
(38.9%) were resistant, 20 genotypes (12%)
were moderately resistant, 30 genotypes (18%)
were moderately susceptible, and 52 genotypes
(31.1%) were susceptible. Elite genotypes with
high yield potential and YR resistance were identified
and have been distributed to the National
Agricultural Research System (NARS) for potential
direct release and/or use as parents after
local adaptation trials by the respective countries.
Further, AM analysis using a mixed linear model
(MLM), corrected for population structure and
kinship relatedness and adjusted for false discovery
rate (FDR), identified five genomic regions
located on wheat chromosomes 2BL, 4BS, 6AS,
6BL, and 7BL which are significantly associated
with genes conferring resistance to YR. The loci
located on chromosome 4BS appeared to be a
novel quantitative trait loci (QTL). These loci may
be useful for choosing parents and incorporating
new YR resistance genes into locally adapted
wheat cultivars.