Pastor Contains Five Chromosomal Regions with Linked or Pleitropic Minor Loci for Stripe and Leaf Rust Resistance


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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.

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Pastor Contains Five Chromosomal Regions with Linked or Pleitropic Minor Loci for Stripe and Leaf Rust Resistance

  1. 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.orgIntroductionPastor is a CIMMYT wheat line that has quantitative , slow-rusting resistance to both leaf rust and stripe rust. It was developed through abreeding 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. Geneticdissection of resistance loci in Pastor was completed by QTL mapping of an F5 RIL population (Avocet × Pastor) screened under both leafand 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 TolucaResults and DiscussionPastor contained five loci for leaf rust resistance and nine loci for stripe rust resistance. Interestingly all of the leaf rust resistance loci werein close genetic proximity to stripe rust loci (shown below). The 1BL and 2BS loci contained the known genes Lr46/Yr29 and Yr31respectively. It is interesting that there was a leaf rust QTL at the same position as the Yr31 major resistance gene. This is a resistance generich region with Lr13 and Lr23 nearby, although seedling tests indicated that those genes were not effective against the pathotypes used inthis study. The 7BL chromosome had two linked QTLs, one for leaf rust resistance and another for stripe rust resistance. They wereapproximately 30cM apart and this haplotype had previously been observed in the related line “Attila” (Rosewarne et al 2008). The 1BSleaf rust and stripe rust QTLs are likely to be different loci although they are very closely linked. The 6BL loci for leaf and stripe rustresistance appear to fall in the same position and further work will be required to determine if they are the same gene. This close linkage ofleaf and stripe rust resistance loci is very useful in a breeding program that focuses on minor, additive gene effects where 4-5 genes arerequired to give high levels of resistance. Evidence provided here indicates that 5 genomic regions can provide a good basis for resistanceto 2 pathogens. This highlights the power of a population breeding strategy that incorporates selection under different environmentsduring the generational advancement process. This breeding strategy favors the selection of linked loci that we observed. Further detailscan 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