Download genetic mapping of leaf and stem rust resistance in - 2016 cwfhb-cwf

GENETIC MAPPING OF LEAF AND
STEM RUST RESISTANCE IN
SPRING WHEAT LINE KU168-2
Mingzhe Che1,2, Brent McCallum1, Curt McCartney1and
Colin Hiebert1
1Morden
Research and Development Centre, Agriculture and Agri-Food Canada,
101 Route 100, Unit 100, Morden, MB, R6M 1Y5, Canada; 2Department of Plant
Pathology, China Agricultural University, Beijing, 100193, China
Introduction
Leaf rust, caused by Puccinia triticina Eriks., is a worldwide disease of
wheat. There are currently over 70 recognized leaf rust resistance
(Lr) genes/alleles, meanwhile, most Lr genes are race-specific,
conditioning resistance to only some races P. triticina (McCallum et al.
2016). The use of resistant cultivars has controlled stem rust (caused
by Puccinia graminis f.sp. tritici Eriks. & Henn.) for many years.
However, the discovery of Ug99, a broadly virulent stem rust race
discovered in Uganda in 1999, has renewed efforts to find new stem
rust resistance genes (Pretorius et al. 2000; Hiebert et al. 2016). In
this study, KU168-2, a spring wheat line, is found to be a good
source of leaf and stem rust resistance. A DH population of the cross
KU168-2/RL6071 was generated and evaluated leaf and stem rust
resistance. Parental lines and 116 DH lines were genotyped using the
Illumina Infinium assay with the iSelect 90K wheat SNP array.
Linkage mapping and identification of the resistance genes in the
population are underway.
Figure 1. Leaf rust field test of KU168-2/RL6071 DH population in 2016. The
results were based on the average of two replicates.
 Resistance to stem rust
 The KU168-2/RL6071 DH population was tested with Pgt race LBB at
seedling stage and all of the DH lines showed ITs 0 including the two
parental lines.
 Segregation of resistant:susceptible lines to Pgt race TPMK was
81:29, fitting a 3:1 ratio (2=0.11, P=0.74).
 Seedling stem rust test with Ug99 is underway.
Materials and Methods
• Seedling test
The parents and the progeny were inoculated with leaf rust races (BBBD,
MBDS and TDBG) and stem rust races (LBB, TPMK and Ug99) after the
first leaf had fully emerged, and rated at two weeks after inoculation.
• Field test
In leaf rust field test, an epidemic mixture of virulence phenotypes
found in Canada during the previous year was used for inoculation.
• genotype and mapping
Genotyped with iSelect 90K wheat SNP array, and constructed genetic
maps using MapDisto with the Kosambi mapping function, detailed in
Hiebert et al. (2016) and McCallum et al. (2013).
Results and Discussion
Figure 2. Stem rust infection types in KU168-2/RL6071 DH
population to race TPMK at seedling stage.
 Gene mapping
 Parental lines and 116 DH lines were genotyped with the iSelect
90K wheat SNP array. 11037 SNPs were polymorphic between the
two parents and 1489 were nonredundant SNPs, which will be
used to map the resistance genes. When the resistance genes are
located on Chromosome, they will be compared with known genes
on the same Chromosome to know if they are new genes.
References
 Resistance to leaf rust
 KU168-2 and RL6071 were tested with six leaf rust races at seedling
stage in greenhouse. KU168-2 showed strong resistance to most of
the six races (Table 1).
 The result of seedling leaf rust test showed correlation with field test,
which suggested there could be seedling resistance genes in the
population. More repeat of seedling and field tests are underway.
 Of 116 DH lines tested with leaf rust in the field 88 were resistant
(Proportion of flag leaf infected  55%) and 28 were susceptible
(Figure 1), which fitted two genes ratio (2=0.05, P=0.83).
Table 1. Leaf rust reaction of KU168-2 and RL6071. 5 plants of each cultivar
were inoculated in greenhouse with different P. triticina races at seedling stage.
Leaf rust races
KU168-2
RL6071
BBBD
1
3
MBDS
1-
3
TDBG
1-
2+
MBRJ
1-
2+
MGBJ
2-
3+
Hiebert et al. (2016) Genetics and mapping of seedling resistance to Ug99 stem rust in
winter wheat cultivar Triumph 64 and differentiation of SrTmp, SrCad, and Sr42. Theor
Appl Genet 129:2171–2177.
McCallum et al. (2013) Physiologic specialization of Puccinia triticina, the causal agent
of wheat leaf rust, in Canada in 2009. Can J Plant Pathol 35:338-345.
McCallum et al. (2016) A review of wheat leaf rust research and the development of
resistant cultivars in Canada. Can J Plant Pathol 38:1-18.
Pretorius et al. (2000) Detection of Virulence to Wheat Stem Rust Resistance Gene Sr31
in Puccinia graminis. f. sp. tritici in Uganda. Plant Dis 84:203.
Acknowledgements
Big thanks to Elsa Reimer, Winnie McNabb, Mira Popovic, Ghassan Mardli,
Leslie Bezte and Taye Zegeye for technical assistance.
China Agricultural University
China Scholarship Council
TJBJ
2-
3+
Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Unit 100, Morden, MB, R6M 1Y5, Canada
Email: [email protected]