Poster presented by Roserwarne, G.M., Singh, R.P., Huerta-Espino J., Herrera S.A., Rebetzke G.J at International Cereal Rust and Powdery Mildew Conference, Aug 28th – 1st Sept 2012, Beijing China.

1. Pastor Contains Five Chromosomal Regions
with Linked or Pleitropic Minor Loci for Stripe
and Leaf Rust Resistance
1,2Garry M ROSEWARNE, 1Ravi P SINGH, 3Juilo HUERTA-ESPINO, 1Sybil A HERRERA-FOESSEL, 4Greg J REBETZKE
1CIMMYT, Apdo Postal 6-641 06600 Mexico D. F., Mexico, 2SAAS, #4 Shizishan Rd, Jinjiang, Chengdu, Sichuan Province, China. 3Campo Experimental Valle de Mexico-INIFAP,
Apartado Postal 10, 56230 Chapingo, Edo. de Mexico, Mexico 4CSIRO Plant Industry, Black Mountain Laboratories, Canberra g.rosewarne@cgiar.org
Introduction
Pastor is a CIMMYT wheat line that has quantitative , slow-rusting resistance to both leaf rust and stripe rust. It was developed through a
breeding program that has a strong focus on incorporating minor, additive genes to confer durable resistance to both diseases.
Generational advancement of populations occurs under alternate epidemics of the two pathogens at two field sites in Mexico. Genetic
dissection of resistance loci in Pastor was completed by QTL mapping of an F5 RIL population (Avocet × Pastor) screened under both leaf
and stripe rust epidemics.
Breeding Cycles in Mexico
Materials and Methods
Ciudad Obregon The population consisted of 148
Season: November to May
Selection for leaf rust resistance
F5 RILs of which 84 were
genotyped with 223 DArT, SSR
and seedling reaction markers to
produce a map containing 31
linkage groups. The population
Leaf rust in Ciudad Obregon was scored for final disease
severity for leaf rust over 3
seasons in Ciudad Obregon and
Toluca: for stripe rust for 3 seasons in
Season: May to November Toluca. A multi-environment
Selection for stripe rust resistance QTL analysis was conducted
Large BC1F1 populations containing multi-genic resistance to both with QTL Network 2.0 (Yang et
rust diseases are screened against leaf rust at Ciudad Obregon.
Selected heads from within a population are threshed and bulk seed al 2005)
is sown at Toluca for screening for stripe rust. Cycles between
Obregon and Toluca continue until fixed lines are produced. Over
time, this has the effect of selecting for genomic regions that contain
linked or pleitropic loci with effects against both diseases
Stripe rust in Toluca
Results and Discussion
Pastor contained five loci for leaf rust resistance and nine loci for stripe rust resistance. Interestingly all of the leaf rust resistance loci were
in close genetic proximity to stripe rust loci (shown below). The 1BL and 2BS loci contained the known genes Lr46/Yr29 and Yr31
respectively. It is interesting that there was a leaf rust QTL at the same position as the Yr31 major resistance gene. This is a resistance gene
rich region with Lr13 and Lr23 nearby, although seedling tests indicated that those genes were not effective against the pathotypes used in
this study. The 7BL chromosome had two linked QTLs, one for leaf rust resistance and another for stripe rust resistance. They were
approximately 30cM apart and this haplotype had previously been observed in the related line “Attila” (Rosewarne et al 2008). The 1BS
leaf rust and stripe rust QTLs are likely to be different loci although they are very closely linked. The 6BL loci for leaf and stripe rust
resistance appear to fall in the same position and further work will be required to determine if they are the same gene. This close linkage of
leaf and stripe rust resistance loci is very useful in a breeding program that focuses on minor, additive gene effects where 4-5 genes are
required to give high levels of resistance. Evidence provided here indicates that 5 genomic regions can provide a good basis for resistance
to 2 pathogens. This highlights the power of a population breeding strategy that incorporates selection under different environments
during the generational advancement process. This breeding strategy favors the selection of linked loci that we observed. Further details
can be obtained from Rosewarne et al (2012) TAG 124: 1283-1294.
Pastor 1BS Pastor 1BL Pastor 2BS Pastor 6BL Pastor 7BL
0.0 wPT-3475
16.2 wPT-9809 0.0 csLV46 0.0 Lr23 0.0 wPT-5176 0.0 wPT-7318
Stripe Rust 2000
Stripe Rust 2002
Stripe Rust 2004
Leaf Rust 2000
Leaf Rust 2002
Leaf Rust 2004
27.7 wPT-6975
29.2 wPT-9032
38.1 wPT-0705
46.3 wPT-2315
58.9 wPT-8168 2.0 gwm818 21.4 wPT-7653
4.9 wPT-9256 27.3 wPT-7602
Stripe Rust 2000
Stripe Rust 2002
Stripe Rust 2004
Stripe Rust 2000
Stripe Rust 2002
Stripe Rust 2009
64.7 wPT-6240
85.4 barc18
Leaf Rust 2000
Leaf Rust 2002
Leaf Rust 2004
Leaf Rust 2002
86.7 wmc419
Stripe Rust 2000
Stripe Rust 2002
Stripe Rust 2004
Leaf Rust 2000
87.9 wmc216
92.0 barc24 8.0 wPT-1264 50.2 wPT-L434
Leaf Rust 2000
93.4 cfd65_ 9.1 Lr13 52.7 wPT-8921
Leaf Rust 2002
94.0 stm515
Leaf Rust 2002
Leaf Rust 2004
Leaf Rust 2004
94.6 barc13 10.9 wPT-0171 69.3 wPT-3939
Stripe Rust 2002
Stripe Rust 2000
Stripe Rust 2009
100.1 gwm413
wPT-3190
Leaf Rust 2000
101.4 wmc406 77.2
102.0 stm050
114.3 wPT-8682
85.0 wPT-L147
116.8 wPT-5678 7.4 cfa229 89.3 wPT-1085
127.9 wPT-3889 94.1 wPT-5069
133.5 wPT-3753
138.8 wPT-5801 8.7 wmc728 17.5 Yr31 17.5 wPT-6329 97.1 wPT-7108
163.0 psp300 100.8 wPT-9813
International Maize and Wheat Improvement Center
Presented at 5th BGRI, Beijing, China Sept 2012