Thomas Miedaner, Wera Eckhoff, Kerstin Flath, Anne-Kristin Schmitt, Philipp Schulz, Johannes Schacht, Philipp Boeven, Wessam Akel, Hubert Kempf & Paul Gruner

Theoretical and Applied Genetics; September 2024; vol 137; article 215

Key message

Stem rust resistance was mainly based on a few, already known resistance genes; for yellow rust resistance there was a combination of designated genes and minor QTLs.

Abstract

Yellow rust (YR) caused by Puccinia striiformis f. sp. tritici (Pst) and stem rust (SR) caused by Puccinia graminis f. sp. tritici (Pgt) are among the most damaging wheat diseases. Although, yellow rust has occurred regularly in Europe since the advent of the Warrior race in 2011, damaging stem rust epidemics are still unusual. We analyzed the resistance of seven segregating populations at the adult growth stage with the parents being selected for YR and SR resistances across three to six environments (location–year combinations) following inoculation with defined Pst and Pgt races. In total, 600 progenies were phenotyped and 563 were genotyped with a 25k SNP array. For SR resistance, three major resistance genes (Sr24, Sr31, Sr38/Yr17) were detected in different combinations. Additional QTLs provided much smaller effects except for a gene on chromosome 4B that explained much of the genetic variance. For YR resistance, ten loci with highly varying percentages of explained genetic variance (pG, 6–99%) were mapped. Our results imply that introgression of new SR resistances will be necessary for breeding future rust resistant cultivars, whereas YR resistance can be achieved by genomic selection of many of the detected QTLs.

See https://link.springer.com/article/10.1007/s00122-024-04731-9

Figure 1:

Correlation plot and histograms for yellow rust and stem rust responses in all populations based on best linear unbiased estimators (BLUEs) on logit scale. Blue line indicates BLUE of Parent 1, red lines of Parent 2. ***P < 0.001 alpha level (colour figure online)