Fine Mapping of the Leaf Rust Resistance Gene Lr65 in Spelt Wheat ‘Altgold’

Abstract

Wheat leaf rust (also known as brown rust), caused by the fungal pathogen Puccinia triticina Erikss. (Pt), is one by far the most troublesome wheat disease worldwide. The exploitation of resistance genes has long been considered as the most effective and sustainable method to control leaf rust in wheat production. Previously the leaf rust resistance gene Lr65 has been mapped to the distal end of chromosome arm 2AS linked to molecular marker Xbarc212. In this study, Lr65 was delimited to a 0.8 cM interval between flanking markers Alt-64 and AltID-11, by employing two larger segregating populations obtained from crosses of the resistant parent Altgold Rotkorn (ARK) with the susceptible parents Xuezao and Chinese Spring (CS), respectively. 24 individuals from 622 F2 plants of crosses between ARK and CS were obtained that showed the recombination between Lr65 gene and the flanking markers Alt-64 and AltID-11. With the aid of the CS reference genome sequence (IWGSC RefSeq v1.0), one SSR marker was developed between the interval matched to the Lr65-flanking marker and a high-resolution genetic linkage map was constructed. The Lr65 was finally located to a region corresponding to 60.11 Kb of the CS reference genome. The high-resolution genetic linkage map founded a solid foundation for the map-based cloning of Lr65 and the co-segregating marker will facilitate the marker-assisted selection (MAS) of the target gene.

Identification of leaf rust resistance loci in a geographically diverse panel of wheat using genome-wide association analysis

“…is highly likely that the locus identified in this study is identical to the Lr65 locus. Zhang et al (2021b) identified TraesCS2A02G001500 encoding NB-ARC and LRR domains as the most prominent candidate gene for Lr65. On chromosome 4B, we identified an MTA (scaffold73828-3_704067) associated with response to TBBGS in the vicinity of two known Lr genes, Lr12 (Dyck et al, 1966) and Lr31 (Singh and McIntosh, 1984).…”

Identification of leaf rust resistance loci in a geographically diverse panel of wheat using genome-wide association analysis

“…Since TBBGS is avirulent against Lr65 and the identified MTA colocalized with markers tightly linked to Lr65 , it is highly likely that the locus identified in this study is identical to the Lr65 locus. Zhang et al (2021b) identified TraesCS2A02G001500 encoding NB-ARC and LRR domains as the most prominent candidate gene for Lr65 . On chromosome 4B, we identified an MTA ( scaffold73828-3_704067 ) associated with response to TBBGS in the vicinity of two known Lr genes, Lr12 (Dyck et al, 1966) and Lr31 (Singh and McIntosh, 1984) .…”

“…(Bremenkamp Barrett et al, 2008) and the two makers, AltID-11(0.55Mb) and Alt-92 (0.61Mb), flanking Lr65 (Zhang et al 2021b). Since TBBGS is avirulent against Lr65 and the identified MTA colocalized with markers tightly linked to Lr65, it is highly likely that the locus identified in this study is identical to the Lr65 locus.…”

“…Since TBBGS is avirulent against Lr65 and the identified MTA colocalized with markers tightly linked to Lr65, it is highly likely that the locus identified in this study is identical to the Lr65 locus. Zhang et al (2021b) identified TraesCS2A02G001500…”

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

“…Great number of genetic loci carrying Lr/QLr were enriched on chromosome 2A. Lr65 originated from spelt wheat (Triticum spelta) was recently fine mapped within a 0.8 cM interval on chromosome 2AS, corresponding to a 60.11 Kb region in the Chinese Spring (CS) wheat reference genome [26]. Lr37 introgressed from Aegilops ventricosa was initially mapped on the chromosome 2AS using restriction fragment length polymorphism (RFLP) and cleaved amplified polymorphic sequence (CAPS) markers [27].…”