Transfer of Leaf Rust and Stripe Rust Resistance Genes Lr62 and Yr42 from Aegilops neglecta Req. ex Bertol. to Common Wheat

Abstract

Continued genetic control of the cereal rusts depends on the availability of effective resistance genes. The wild relatives of wheat (Triticum aestivum L.) constitute a source of such genes. Wheat leaf rust (Puccinia triticina Eriks.) resistant Aegilops neglecta accession 155 was crossed with ‘Chinese Spring’. Resistant progeny were initially backcrossed to Chinese Spring and later to Chinese Spring‐Short (a short‐strawed near‐isogenic line) to develop an addition line. Advanced backcross progeny segregated for a resistance gene (designated Lr62) located on an addition chromosome, as well as a resistant phenotype apparently contributed by dominant complementary genes of the wheat genomes. On its own, Lr62 produced infection type (IT); however, in the presence of the two complementary genes its expression was modified to an intermediate response. The addition chromosome appeared to have homeology with group 3 chromosomes of wheat. While attempting to transfer the resistance through allosyndetic pairing induction to a group 3 wheat chromosome, a spontaneous translocation occurred. Aneuploid and microsatellite analyses showed that the translocation involved wheat chromosome 6A, suggesting that the addition chromosome may also have partial homeology to group 6. Microsatellite and meiotic pairing data suggested the presence of a large segment of foreign chromatin replacing the entire 6AS arm and a proximal part of 6AL. Lr62 was effective against a wide range of South African and western Canadian Puccinia triticina pathotypes. In addition to Lr62, the translocation line, 03M119‐71A, carried a seedling stripe rust resistance gene (designated Yr42) effective against South African pathotypes of P. striiformis The resistance genes can be of significant commercial value, however, it may be necessary to further tailor this fairly big translocation through allosyndetic pairing induction.

Genome-wide DArT and SNP scan for QTL associated with resistance to stripe rust (Puccinia striiformis f. sp. tritici) in elite ICARDA wheat (Triticum aestivum L.) germplasm

“…The Chromosome 6A is known to harbour three stripe rust resistance QTL including Yr42 on the long arm (Marais et al 2009) and Yr38, which was not assigned to a specific arm (Marais et al 2006). Results from LD analysis showed high LD between these markers (R 2 ranged between 0.27 and 0.56).…”

Identification of Molecular Markers Linked to Leaf Rust Resistance Genes in Wheat and Their Detection in the Local Near-Isogenic Line

“…RAPD markers provide a quick and cost effective method for generating genetic maps and analyzing population. MAS could be useful in the development of highly resistant germplasm based on new combinations of Lr genes are Lr53 [22], Lr56 [23], Lr57 [24], Lr59 [25], Lr62 [26], Lr63 and Lr66 [27].…”

Registration of Spring Wheat Sources of Leaf Rust Resistance Genes Lr53, Lr56, Lr59, and Lr62

“…Resistance genes Lr62 and Yr42 were introgressed from Ae. neglecta (Marais et al, 2009). The original translocation was to chromosome 6A and consisted of an almost complete Ae.…”