Pyramiding adult-plant powdery mildew resistance QTLs in bread wheat

Abstract

Pyramiding of quantitative trait loci (QTLs) can be an effective approach for developing durable resistance to powdery mildew in wheat (Triticum aestivum L.). The Chinese wheat cultivars Bainong 64 and Lumai 21, with outstanding agronomic traits, possess four and three QTLs, respectively, for adult-plant resistance (APR) to powdery mildew. To achieve optimal durable resistance, 21 F6 lines combining two–five powdery mildew APR QTLs were developed from the cross Bainong 64/Lumai 21 using a modified pedigree selection. These lines were planted in a randomised complete block design with two replicates in Beijing during the 2009–10 and 2010–11 cropping seasons, and were evaluated for powdery mildew response using the highly virulent Blumeria graminis f. sp. tritici isolate E20. Based on the phenotypic data of both maximum disease severity (MDS) and area under the disease progress curve (AUDPC), analysis of variance indicated that there were highly significant effects of QTL combinations on reducing powdery mildew MDS and AUDPC. Six pyramided QTL combinations possessing QPm.caas-1A and QPm.caas-4DL in common along with one or more of the others expressed better APR to powdery mildew than the more resistant parent, Bainong 64. Thus, pyramiding these two QTLs with one or more of QPm.caas-2BS, QPm.caas-2BL, and QPm.caas-2DL from Lumai 21 could be a desirable strategy to breed cultivars with high levels of durable resistance to powdery mildew. Experienced breeders with a good knowledge of minor genes can achieve APR by phenotypic selection, and selection by molecular markers will still require uniform field testing for powdery mildew and disease phenotype to validate the resistance. These results provided very useful information for pyramiding APR QTLs in wheat breeding programs.

Overview and Application of QTL for Adult Plant Resistance to Leaf Rust and Powdery Mildew in Wheat

“…For example, Lumai 21 was crossed with Bainong 64 to combine QTL identified in both parents by QTL mapping of genes for APR to powdery mildew in Lumai 21 (Lan et al, 2010b) and Bainong 64 (Lan et al, 2009), which were competitive cultivars in China for many years. Among 21 selected F 6 lines, 12 had significantly lower area under disease progress curve (AUDPC) values, better agronomic traits than their parents, and carried 3 to 5 minor QTL determined by testing with closely linked molecular markers (Bai et al, 2012). Two APR QTL QPm.caas ‐ 1AL and QPm.caas ‐ 4DL from Bainong 64 played more significant roles in reducing disease severity, and pyramiding these two QTL with other QTL from Lumai 21 would be an ideal strategy to obtain high to near‐immune levels of resistance (Bai et al, 2012).…”

“…Among 21 selected F 6 lines, 12 had significantly lower area under disease progress curve (AUDPC) values, better agronomic traits than their parents, and carried 3 to 5 minor QTL determined by testing with closely linked molecular markers (Bai et al, 2012). Two APR QTL QPm.caas ‐ 1AL and QPm.caas ‐ 4DL from Bainong 64 played more significant roles in reducing disease severity, and pyramiding these two QTL with other QTL from Lumai 21 would be an ideal strategy to obtain high to near‐immune levels of resistance (Bai et al, 2012). The lines with pyramided minor genes showed good APR to powdery mildew on the basis of field evaluations (Bai et al, 2012).…”

“…Two APR QTL QPm.caas ‐ 1AL and QPm.caas ‐ 4DL from Bainong 64 played more significant roles in reducing disease severity, and pyramiding these two QTL with other QTL from Lumai 21 would be an ideal strategy to obtain high to near‐immune levels of resistance (Bai et al, 2012). The lines with pyramided minor genes showed good APR to powdery mildew on the basis of field evaluations (Bai et al, 2012). Thus, the current result confirmed that pyramiding QTL can be a suitable strategy for breeding highly and durably resistant wheat cultivars.…”

Race composition ofBlumeria graminis(DC) Speer f. sp.triticiin the south of Ukraine and effectiveness ofPm-genes in 2004–2013

“…A lot of researchers established that resistance based on Quantitative Trait Loci (QTL) or the combination of minor genes with effective race-specific genes provides long-term resistance to Blumeria graminis (DC) Speer f. sp. tritici (Miedaner and Flath 2007;Mikulová et al 2008;Bai et al 2012). According to the results of Chen et al (2009) the QTL QPm.osu.1A associated with the race-specific Pm3a allele.…”

“…The third strategy is combining race-specific genes with slow-mildewing resistance. It can be implemented successfully when breeding material selected for crosses possesses high partial resistance and completely effective major genes (Wang et al 2005;Hysing et al 2007;Liatukas and Ruzgas 2008;Bai et. al.…”