Genetic Control of Effective Seedling Leaf Rust Resistance in <i>Aegilops biuncialis</i> Vis. Accessions from the VIR Collection

Leaf rust (caused by <i>Puccinia triticina</i> Erikss., <i>Pt</i>) is a severe foliar disease of cultivated wheat worldwide. Severe development of the disease results in significant losses in seed yield and quality. Growing immune varieties is the most rational method for <i>Pt</i> control in terms of effectiveness and ecological safety. However, the gene pool of cultivated wheat is very narrow for seedling <i>Pt</i> effective resistance genes, which hampers breeding for this trait. One of the well-known methods to broaden genetic diversity for resistance is the introgression of highly effective genes from wild relatives into the genomes of cultivated wheat. The <i>Aegilops</i> L. species have been proven to be perfectly suited for this purpose. No gene for <i>Pt</i> resistance has been transferred to wheat from <i>Aegilops biuncialis</i> Vis. (Lorent’s goatgrass) up to now. Previously, we selected eight accessions of the species from the VIR (N.I. Vavilov All-Russian Institute of Plant Genetic Resources) genebank that showed a perfect level of resistance to leaf rust. In this research, we studied the genetic control of resistance using hybridological, phytopathological, and molecular analyses. According to the F₁–F₃ hybrid evaluation results, each accession possesses one dominant gene for <i>Pt</i> resistance, and genes in different accessions are allelic or very tightly linked. Phytopathological test clone analysis showed that this gene is not identical to <i>Lr9</i>, <i>Lr19</i>, <i>Lr24</i>, <i>Lr39</i>, and <i>Lr47</i>, which are effective against <i>Pt</i> populations in some areas of Russia. This conclusion was partially supported by the results of the identification of DNA markers specific to these genes in bread wheat. Thus, we identified one dominant gene (temporarily symbolized as <i>LrBi1</i>) for effective seedling <i>Pt</i> resistance; it is recommended for introgression to cultivated wheat via interspecific hybridization.