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Cereal Research Communications
Authors: A. Kokhmetova, A. Madenova, G. Kampitova, R. Urazaliev, M. Yessimbekova, A. Morgounov, and L. Purnhauser

. Gultyaeva , E.I. 2012 . Methods for the identification of genes for resistance of wheat to leaf rust using DNA markers and characteristics of effective Lr genes . Russian Academy of Agricultural Sciences: VIZR. Saint- Petersburg

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The breeding and cultivation of resistant wheat varieties is an effective way of controlling leaf rust ( Puccinia triticina Eriks.). The use of molecular markers facilitates the incorporation of the major leaf rust resistance genes ( Lr genes) responsible for resistance into new varieties and the pyramiding of these genes. Marker-assisted selection was used to incorporate the Lr genes currently effective in Hungary ( Lr9 , Lr24 , Lr25 , Lr29 ) into winter wheat varieties. The Lr genes were identified using STS, SCAR and RAPD markers closely linked to them. Investigations were made on how these markers could be utilised in plant breeding, and near-isogenic lines resembling the recurrent variety but each containing a different Lr gene were developed to form the initial stock for the pyramiding of resistance genes. The results indicate that the marker-assisted selection technique elaborated for resistance genes Lr24 , Lr25 and Lr29 can be applied simply and effectively in wheat breeding, while the detection of the Lr9 marker is uncertain.

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value of molecular markers for Lr genes and characterization of leaf rust resistance of German winter wheat cultivars with regard to the stability of vertical resistance . Eur. J. Plant Pathol. 130 : 559 – 575

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In 2005–2008 virulence of the wheat leaf rust population was studied on Thatcher near-isogenic lines with Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr9, Lr10, Lr11, Lr15, Lr17, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28 . Samples of leaf rust were obtained from different parts of the Czech Republic. A total of 233 wheat leaf rust isolates were analyzed. Resistance gene Lr9 was effective to all tested isolates as in the four previous years. Virulence to Lr19 (0.8% of the analysed isolates) was found. Gene Lr24 conditioned resistance to almost all collections and a lower frequency of virulence was also observed on Lr2a and Lr28 . Twenty-six winter wheat cultivars, seven spring wheat cultivars and seven winter triticale cultivars registered in 2005–2008 were tested with 7 leaf rust isolates. Winter wheat cultivars Biscay, Mulan and Orlando were resistant to all isolates and were also resistant in field trials.

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Cultivation of winter wheat varieties in the West Siberian region of Russia has competitive advantages compared to spring varieties: utilization of spring-summer moisture, early maturation and harvest and a high yield potential. The poor resistance of winter varieties to foliar diseases results in significant yield losses and facilitates the spread of pathogens to the spring wheat cultivars. The present study was conducted to evaluate the effectiveness of molecular markers specific for VRN-1 and Lr loci in selecting winter wheat genotypes resistant to leaf rust. The winter wheat cultivars Biyskaya ozymaya and Filatovka were crossed with spring wheat introgression lines 21-4 and 5366-180 and the spring wheat cultivar Tulaikovskaya 10 carrying LrTt2, LrAsp5 and Lr6Ai#2 loci from Triticum timopheevii, Aegilops speltoides and Thynopyrum intermedium, respectively. To identify winter wheat plants homozygous for target loci, F2 populations were screened with functional markers to VRN-1 genes and with markers specific for alien genetic material. Based on the genotyping analysis of 371 F2 plants a total of 44 homozygous genotypes with winter habit was identified. There were eight genotypes containing Lr loci among them. Evaluation of F2-derived F3-4 families for both seedling and adult resistance showed that only one F3-4 family had moderate susceptible reaction type to the field population of leaf rust. Others ranged from nearly immune to resistant with severity of 5%. The data also indicated the utility of the VRN-1 allele-specific markers for detection of genotypes with winter habit without vernalization at early stages of plant breeding.

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Acta Agronomica Hungarica
Authors: M. Hudcovicová, V. Šudyová, S. Šliková, E. Gregová, J. Kraic, F. Ordon, D. Mihálik, V. Horevaj, and Z. Šramková

Marker-assisted selection (MAS) is an efficient modern method for transferring alleles or specific chromosome segments including important agronomic traits into elite cultivars. This approach makes genotypic selection possible, whereby the selection process is more effective. The Research Institute of Plant Production Piešťany uses genetic markers linked to important traits in the following pre-breeding programmes: 1. development of winter barley lines resistant to BaYMV/BaMMV, 2. development of spring barley lines resistant to BYDV, 3. development of winter wheat lines resistant to leaf rust (gene pyramiding), 4. improvement of wheat quality by new combination(s) of known HMW-GS and/or by introduction of novel HMW-GS alleles. Several hundreds of genotypes are usually analysed for the presence or absence of linked molecular markers and selected for use in breeding programmes.

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Transfer of genetic material from tetraploid species, Triticum timopheevii Zhuk, resistant to diseases into common wheat Triticum aestivum L. has been carried out. Six common wheat cultivars were used. The process of hybrid forms stabilization have been studied in details; identification of Triticum timopheevii genetic material in genome of introgressive lines (2n = 42) resistant to leaf rust (Puccinia triti- cina Erikss.) has been carried out. Donors of rust resistance have been developed and the genetic control of the character has been studied. The resistance of obtained lines has been shown to be due to Lr genes, non- allelic to effective Lr genes from world collection.

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Isolates of Puccinia triticina were obtained from wheat and triticale nurseries and fields in Hungary. Pathotypes were determined on 15 Thatcher wheat lines that are near-isogenic for leaf rust resistance. Thirteen pathotypes were identified from 70 Puccinia triticina isolates collected from infected wheat plants, and 2 pathotypes were identified from 12 Puccinia triticina isolates obtained from infected triticale leaves. Most pathotypes identified in Hungary were virulent to resistance genes Lr2b, Lr2c, Lr3, Lr11, Lr17, Lr21, Lr26, but pathotypes from triticale were virulent only to Lr2b, Lr2c and Lr11. Among the examined 15 Lr genes Lr2a, Lr9, Lr19, Lr23, Lr24 and Lr28 were highly effective. The most common pathotypes were 43522, 43722 and 53522 on wheat plants, among them 53522 was new in rust populations. Pathotypes 41000 and 41100 obtained from infected triticale plants were identified for the first time in the Hungarian Puccinia triticina populations. The number of pathotypes with virulence to Lr1, Lr2b and Lr21 increased from 1999 to 2004. Virulence to other Lr genes declined, because a lot of susceptible cultivars were removed from production during the past five years. In 2004, most predominant cultivars grown in Hungary were resistant or moderately resistant to leaf rust.

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The objectives of this research were to examine the inheritance of leaf rust resistance genes in the Iranian wheat cultivar ‘Marvdasht’, which is highly resistant to leaf and stripe rusts, and to identify Lr genes present in this cultivar using molecular markers. The genetic basis of resistance to the leaf rust pathogen (Puccinia triticina) in ‘Marvdasht’ was studied in F2:3 populations derived from crosses of Bolani (susceptible cultivar) × Marvdasht. Isolates 84-1 and 85-28 of P. triticina, which are the predominant isolates in Iran, were used to examine the segregation of resistance originating from ‘Marvdasht’. The results indicated that resistance in ‘Marvdasht’ to Puccinia triticina isolate 84-1 was governed by two dominant seedling resistance genes Lr1 and Lr17a. Allelism studies using an F2 population derived from a cross between ‘Falat’ (Seri 82) and Marvdasht indicated that resistance in Marvdasht was not due to the resistance gene Lr26 present in ‘Falat’. With the application of a previously developed molecular marker for Lr1, the STS marker RGA-567-5, the presence of Lr1 was verified in Marvdasht. Based on bulk segregant analysis, Lr17a was mapped to the distal end of chromosome 2AS and was closely linked to microsatellite marker Xbarc212 at a distance of 3.7 cM. In conclusion, the presence of Lr1 and Lr17a was confirmed in the cultivar Marvdasht.

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Cereal Research Communications
Authors: H. Khan, S.C. Bhardwaj, O.P. Gangwar, P. Prasad, P.L. Kashyap, S. Savadi, S. Kumar, and R. Rathore

A set of forty wheat cultivars comprising bread wheat, durum and triticale identified during 2010–2014 were tested for resistance to Indian pathotypes of leaf, stem and yellow rusts at seedling stage under controlled conditions. Eight Lr genes (Lr1, Lr3, Lr10, Lr13, Lr14a, Lr23, Lr24 and Lr26) were characterized based on differential interactions with specific rust races. Genes Lr23, Lr26 and Lr13 conferred leaf rust resistance in most of the accessions. Three Yr genes (YrA, Yr2 and Yr9) were inferred in 40 genotypes, where Yr2 followed by Yr9 were most frequent in conferring stripe rust resistance. Ten Sr genes, namely, Sr2, Sr5, Sr8a, Sr7b, Sr9b, Sr9e, Sr11, Sr13, Sr24 and Sr31, were postulated in these lines with predominance of Sr11, Sr31 and Sr2. These Lr, Sr and Yr genes were observed singly or in combination. Robust DNA markers were used to identify adult plant resistance genes Yr18/Lr34/Sr57, Lr68 and Sr2 and all stage resistance genes Lr24/Sr24, Sr28 and Yr9/Lr26/Sr31. STS marker iag95 showed presence of Yr9 in four additional cultivars which were resistant to one or more rusts. Gene Sr28 was identified in seven durum cultivars with the wPt7004 marker. This is first report of Sr28 being present in many Indian wheat cultivars. CsGs-STS marker identified Lr68 in nine cultivars.

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