GENETICS OF RESISTANCE TO YELLOW RUST IN THE BREAD WHEAT GENOTYPES PI250413 AND C591

Abstract

The yellow rust of wheat, caused by Puccinia striiformis f. sp. tritici, has evolved rapidly in recent years, causing significant economic losses in bread wheat (Triticum aestivum L.) and durum wheat (Triticum durum D.). Management of P. striifomis is based on genetic resistance, which is the most economical and environmentally safe method. The objective of this research was to estimate the number of genes that condition resistance to P. striiformis in the bread wheat genotypes PI250413 and C591 and to identify the presence or absence of genes Yr46 and Yr67. F₃, F₄ and F₅ families were generated from the Apav × PI250413 cross and the F₃ of the PI250413 × C591 cross, which were evaluated under field and greenhouse conditions during 2019 and 2020. Artificial epidemics were created using the MEX14.191 race of P. striifomis. The number of genes was estimated by using the phenotypic ratios. The presence of the genes was corroborated with SNP molecular markers. The behavior of the families in adult plant and the analysis of X² indicated the presence of two to three genes. The frequencies of the distributions observed at seedling stage were adjusted to the segregation of one gene. Results indicated that PI250413 and C591 have quantitative and qualitative resistance. Molecular analysis confirmed the presence of Yr47 and Yr67 in parents PI250413 and C591. The Yr46/Yr67 combination is effective both in seedlings and in adult plants and considerably decreases infection levels to almost immunity at least in PI250413 and C591; these genotypes are suitable for use as parents in breeding programs to achieve durable resistance to yellow rust.