Mapping of the leaf rust resistance gene Lr38 on wheat chromosome arm 6DL using SSR markers

Abstract

Leaf rust caused by the fungus Puccinia triticina is one of the most important diseases of wheat (Triticum aestivum) worldwide. The use of resistant wheat cultivars is considered the most economical and environment-friendly approach in controlling the disease. The Lr38 gene, introgressed from Agropyron intermedium, confers a stable seedling and adult plant resistance against multiple isolates tested in Europe. In the present study, 94 F 2 plants resulting from a cross made between the resistant Thatcherderived near-isogenic line (NIL) RL6097, and the susceptible Ethiopian wheat cultivar Kubsa were used to map the Thatcher Lr38 locus in wheat using simple sequence repeat (SSR) markers. Out of 54 markers tested, 15 SSRs were polymorphic between the two parents and subsequently genotyped in the population. The P. triticina isolate DZ7-24 (race FGJTJ), discriminating Lr38 resistant and susceptible plants, was used to inoculate seedlings of the two parents and the segregating population. The SSR markers Xwmc773 and Xbarc273 Xanked the Lr38 locus at a distance of 6.1 and 7.9 cM, respectively, to the proximal end of wheat chromosome arm 6DL. The SSR markers Xcfd5 and Xcfd60 both Xanked the locus at a distance of 22.1 cM to the distal end of 6DL. In future, these SSR markers can be used by wheat breeders and pathologists for marker assisted selection (MAS) of Lr38-mediated leaf rust resistance in wheat.

Identification of leaf rust resistance genes i n selected Argentinean bread wheat cultivars by gene postulation and molecular markers

“…is one of the most common foliar diseases of this crop worldwide (Oelke and Kolmer, 2004;Mebrate et al 2008). In South America, leaf rust occurs annually in approximately 9 million ha of wheat, causing yield losses of over 50% in severe epidemics and is the primary reason of cultivar replacement.…”

“…In this context, a better knowledge on the identity of effective Lr genes present in adapted cultivars that can be used as donors of resistance in wheat breeding programs could greatly improve the efficiency of developing resistant cultivars by using these genes per se or by stacking different resistant genes in a given cultivar, a process also known as gene pyramiding (Messmer et al 2000); thereby helping to avoid the release of cultivars that are genetically uniform (Mebrate et al 2008).…”

“…Gene postulation is the most frequent method to determine the presence of the probable race-specific seedling resistance genes (Lr genes) in a host cultivar, many researchers have used this method to for identifying Lr genes in a group of wheat genotypes (Kolmer, 2003;Oelke and Kolmer, 2004;Wamishe and Milus, 2004;Hysing et al 2006;Mebrate et al 2008). In this procedure, a host cultivar is evaluated against a collection of Puccinia triticina Eriks.…”

PCR-based molecular markers linked to the leaf rust resistance gene Lr19 in different bread wheat cultivars

“…The obtained results can be used in breeding and genetic programs on creation of forms resistant to leaf rust pathogen populations in Azerbaijan. Thus, information about the existence of effective Lrgenes in adapted varieties that can be used as donors for resistance, and usage of these distinct genes or by pyramiding of different resistance genes in the genotype can significantly improve the efficiency of breeding of resistant varieties [12], thus assisting to avoid the creation of varieties that are genetically homogeneous [3].…”

“…One of the common and harmful diseases of cereal crops is brown leaf rust caused by basidium fungus Puccinia recondite f. sp. tritici [1][2][3].…”