Molecular mapping of the Aegilops speltoides-derived leaf rust resistance gene Lr36 in common wheat (Triticum aestivum)

Abstract

Leaf rust caused by Puccinia triticina Eriks. is the most prevalent wheat rust worldwide and occurs annually wherever wheat is grown. The most economical and environmentally friendly method to control this fungal disease is genetic resistance, which is achieved through deploying effective resistance genes. Tightly-linked molecular markers facilitate gene tagging and their deployment with other resistance genes which in turn contribute to durable leaf rust resistance. The leaf rust resistance gene Lr36 derived from Aegilops speltoides Taush and introgressed into hexaploid wheat by backcrossing, is located on chromosome 6BS. Despite detection of low frequencies of virulence for this gene, no molecular markers are available for marker-assisted selection in disease resistance breeding. Therefore, this research aimed at analysis of simple sequence repeat (SSR) markers linked with Lr36 in an F 2 population from a cross between the Lr36-carrying line (ER84018) and the susceptible cultivar; Boolani. Of 36 primer pairs on chromosome 6BS tested for polymorphism in parents and resistant and susceptible bulks, eight were polymorphic of which the markers Xgwm88 and Xcfd13 anked Lr36 by 3.8 and 5.2 cM, respectively. Evaluation of these markers on 35 genotypes from different backgrounds including few Australian wheat leaf rust differential sets, Iranian landraces and cultivars, and several cultivars and/or breeding lines from Switzerland and Afghanistan, con rmed that they can be used in selection for Lr36 in wheat breeding programs.

Mapping of Aegilops speltoides derived leaf rust and stripe rust resistance genes using 35K SNP array

“…speltoides . The presence of Lr36 in the present study was tested by amplifying linked SSR Xgwm88 [ 68 ] which was monomorphic between IL sp3603 and WL711 indicating that the leaf rust resistance gene mapped in the present study is not Lr36 . Moreover, pathotypes 77−5 and 77−9 have gained virulence against this gene, while Lr sp3603 resistance mapped in the current study, is effective.…”

Genetics of Resistance to Leaf Rust in Wheat: An Overview in a Genome-Wide Level

“…The seedling resistance gene Lr36 was derived from Ae. speltoides and mapped between SSR markers Xgwm88 and Xcfd13 on chromosome 6BS [107].…”