Molecular Markers for Alien Leaf Rust Resistance Genes and Marker Assisted Selection Against Puccinia Recondita F. Sp Tritici in Wheat (Triticum Aestivum L.). PDF Download

Author: D. P. Cherukuri
Publisher:
ISBN:
Category :
Languages : en
Pages : 117

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Author: Hsiao-Yi Hung
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Wheat (Triticum aestivum L. em. Thell, 2n=6x=42, AABBDD) is subjected to significant yield losses by the endemic leaf rust pathogen, Puccinia triticina (Roberge ex Desmaz. F. sp. tritici). Breeding for resistance to this disease is a more appropriate option both environmentally and economically over fungicidal application. More than 57 leaf rust resistance genes in wheat have been identified and many of the resistance genes have been successfully introgressed into resistant cultivars, yet the continuous shifting of predominant races of P. triticina continues to be a challenge to breeders. Pyramiding multiple resistance genes into a single resistant cultivar is one of the preferred strategies to develop superior disease resistant cultivars. Efficient pyramiding requires the utilization of markers closely linked to the resistance genes. The objectives of this study were to characterize a novel source of resistance to leaf rust introgressed into the breeding line WX93D180-R-8-1, to determine its inheritance, map position, and linkage with molecular markers suitable for marker assisted selection. According to the pedigree of WX93D180, TX86D1310*3/TTCC417, the resistance in this breeding line should be derived from TTCC417 (Turkey tritici cereal collection), which was thought to be Triticum monococcum, which is a diploid species made up of only the A genome. However, our marker analyzes results indicated the resistance gene is located in the D genome and has the same location as the cloned leaf rust resistance gene Lr21. We verified the result in our population using primers from Lr21 and found the same segregation pattern with the phenotypic data (disease response). Therefore the pedigree is incorrect, TTCC417 was misidentified, or the resistance was not from TTCC417.

Author: Xiangyu (Bruce) Pei
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Leaf rust, caused by Puccinia triticina Eriks. (Pt = P. recondita Rob. Ex Desmaz. F. sp. tritici), is an economically significant pathogen affecting durum wheat (Triticum turgidum var. durum L.) crops worldwide. Genetic resistance is one of the most effective and environmentally friendly methods to control leaf rust in wheat. New sources of resistance genes need to be identified due to the threat of new Pt races to durum wheat production. Marker assisted selection (MAS) is a highly efficient method to select resistance genes in breeding programs particularly to pyramid multiple resistance genes in new varieties. The objective of this study was to characterize and map leaf rust resistance genes in a Canadian durum wheat Strongfield. A double haploid (DH) mapping population of 87 DH lines was developed from the cross Strongfield/Blackbird. Seedling rust tests with Pt isolates 12-3 MBDS, 06-1-1 TDBG, 128-1 MBRJ, 74-2 MGBJ, and 77-2 TJBJ revealed a single hypersensitive leaf rust resistance gene. Three genes segregated for resistance to isolate 1-1 BBBD at the seedling stage, one of which controlled resistance to the other five Pt isolates. Blackbird contributed one of the seedling resistance genes effective against isolate 1-1 BBBD. Parental lines and 87 DH lines were genotyped using the Illumina Infinium assay with the iSelect 90K wheat SNP array. A database search using the DNA sequences of linked markers provided a putative location in the Chinese Spring reference genome sequence. The gene conferring resistance to the six isolates used in the study mapped to the long arm of chromosome 3A and was temporarily designated as LrStr_3A. No leaf rust resistance gene has been detected in this region previously. Quantitative trait locus (QTL) analysis identified eight QTL controlling leaf rust resistance in field leaf rust nurseries. One of these QTL mapped to chromosome 3AL as the same region of LrStr_3A. Another QTL mapped to the expected location of the adult plant resistance (APR) gene Lr46 based upon the marker csLV46G22. Kompetitive allele-specific PCR (KASP) markers were developed for LrStr_3A that will be useful for MAS.

Author: H.T. Buck
Publisher: Springer Science & Business Media
ISBN: 1402054971
Category : Science
Languages : en
Pages : 764

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Providing a unique overview to wheat and related species, this book comprises the proceedings of the 7th International Wheat Conference, held in Mar del Plata, Argentina, at the end of 2005. Leading scientists from all over the world, specialized in different areas that contribute to the better understanding of wheat production and use, review the present achievements and discuss the future challenges for the wheat crop.

Author: Jo-Mari Lottering
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Wheat is one of the major food crops consumed by man and is grown in a wide range of environments. One constraint in the production of wheat is the different diseases attack the crop. One such a diseases is leaf rust. Leaf rust is caused by Pucdnia recondita f.sp. trifid and is the most widespread and regularly occurring rust on wheat. Researchers are continually searching for new resistance genes and to date 47 leaf rust resistance genes (Lr) have been designated in wheat. Three molecular techniques RAPDs (random amplified polymorphic DNA), AFLPs (amplified fragment length polymorphism) and SSRs (microsatellites) were used to identify and analyse the distances between different cereal genotypes. Four RAPD primers, three AFLP primers and two SSR primers were used to analyse the wheat genotypes, x-tritosecale and rye. The average polymorphisms obtained from the AFLPs were 100 polymorphisms per AFLP primer combination, and is much higher than with the RAPD primers (11-16 polymorphic loci). The four RAPD primers failed to identify unique molecular markers for the wheat genotypes. The AFLP primers were able to distinguished between the 'Kiewiet', rye, 'SA463/*4Palmiet', 'SA684', TA2460' and 'KG90WGRClO' genotypes. The SSR primer pair XGWM122150 was able to amplify a fragment from the A or B genome. The pairwise distances between the genotypes revealed that the wheat genotypes were genetically very close, with an average distance value of 0.29 between the genotypes. The genotypes, 'TA2460', 'TAMI07' and 'KS90WGRCI0', were not closely related to the South African wheat genotypes and were genetically very close to each other. The rye and 'Kiewiet' genotypes were grouped as an outgroup by the UPGMA analysis and were the least closely related to the cereal genotypes. RAPD (Random amplified polymorphic DNA) and AFLP (amplified fragment length polymorphism) analysis were used to identify molecular markers linked to leaf rust resistance gene Lr41. Bulk and parental lines were screened with 380 RAPD primers and 64 AFLP primer combinations. A total of 3190 RAPD and 1859 AFLP loci, respectively were screened for linkage to the resistance gene. Twelve fragments (seven RAPD and five AFLP), nine in coupling phase and three in repulsion phase, were identified as putative markers for the leaf rust resistance gene Lr41. Segregation analysis of these markers in a BC2F2 population revealed varying linkage distances that ranged from 2.8 to 33 cM. The coupling phase AFLP marker E-AAG:M-CTA300 was converted into a sequence characterised amplified region (SCAR) marker. AFLP markers have potential for marker assisted selection breeding programs, provided it can be converted into SCARs or equivalent marker typed systems.

Author: Mallorie Lewarne
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Of the fungal diseases that can infect bread wheat (Triticum aestivum L.), leaf rust, caused by Puccinia triticina Eriks. is the most common and widespread. Pyramiding multiple resistance genes in a cultivar using conventional breeding techniques is often expensive and time consuming. Alternatively, marker assisted selection (MAS) allows for accelerated and accurate selection of resistance gene combinations. The objectives of this study were to characterize two leaf rust resistance genes: an adult plant resistance (APR) gene, hypothesized to be Lr46, from wheat line BW278, and a seedling resistance gene, Lr2a, from wheat cultivar Superb. To characterize the APR, two mapping populations derived from BW278 were genotyped with the iSelect 90K wheat SNP array. Both populations were evaluated for leaf rust in inoculated field nurseries for five years. Quantitative trait locus (QTL) analysis revealed two QTL controlling resistance in the BW278/AC Foremost population, one in the region of interest, chromosome 1B and another on chromosome 5A. Two QTL were detected in Superb/BW278, on chromosomes 4B and 5B, however no QTL were detected in the region of interest on 1B. The QTL on 1B in BW278/AC Foremost, designated QLr.mrdc-1B, was tightly linked to both csLV46G22 and DK0900, two markers previously described as tightly linked to the Lr46 locus. Ten SNPs in the QLr.mrdc-1B region were selected for kompetitive allele-specific PCR (KASP) assay design. To characterize Lr2a, two mapping populations derived from Superb (Superb/BW278 & Superb/86ISMN 2137) were genotyped with the iSelect 90 K wheat SNP array, and evaluated with a single race of P. triticina under greenhouse conditions. Two-point linkage analysis between the marker data and phenotypic infection type ratings revealed that the gene mapped to chromosome 2DS in both mapping populations. The linkage maps generated for the two mapping populations had 11 SNP markers in common and displayed collinearity. Seven SNPs that either flanked or co-segregated with Lr2a in Superb/BW278 were selected for KASP assay design. Of the seven markers, kwh740 (Excalibur_c1944_1017) was polymorphic in both populations and displayed clear clusters, making it the most applicable for use in MAS.

Author: Marley Boyce
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Wheat leaf rust, caused by Puccinia triticina Eriks. (= P. recondita Rob. Ex Desmaz. f. sp. tritici), is the most widespread disease of wheat worldwide and causes average annual yield losses of 5 to 25%. The emergence of a new predominant race of leaf rust, TDBG, in the 2004 Canadian virulence survey led to the identification of a second leaf rust resistance gene segregating in the Thatcher-Lr1 near-isogenic differential line, RL6003, which produced an unusual mesothetic infection type. This gene was subsequently isolated in a Thatcher background and temporarily designated as LrCen (Tc-LrCen). A cross was made with a susceptible parent (Tc-LrCen/ Sumai3-lr34) and a doubled haploid (DH) mapping population was generated from the hybrids. Parental lines and 180 double haploid (DH) individuals were phenotyped with race TDBG and a 1:1 ratio was observed in the DH population. Parental lines and 94 DH individuals were genotyped with the Illumina Infinium assay using a custom iSelect 90K wheat SNP array. Two-point linkage between the phenotype and polymorphic SNP markers identified linked markers. A BLAST search of linked SNP sequences was performed against the Wheat Survey Sequence providing a putative chromosomal location of 7AL. Subsequent mapping with microsatellite markers confirmed LrCen was located on the long arm of chromosome 7A flanked by gwm344 (9.5 cM) and cfa2240 (0.6 cM) as well as a group of co-segregating SNPs also at a genetic distance of 0.6 cM. When the SNP sequences were converted to the kompetitive allele specific PCR (KASP) markers they were found to be dominant, making them less useful for marker assisted selection in populations with heterozygotes. LrCen mapped distal to Lr20; the only other Lr gene previously identified on chromosome 7AL.

Author: RA McIntosh
Publisher: CSIRO PUBLISHING
ISBN: 0643103023
Category : Technology & Engineering
Languages : en
Pages : 308

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Although stem rust has been controlled by means of resistant cultivars, leaf and stripe rust continue as problems for many growing areas of the world. Wheat Rusts: An Atlas of Resistance Genes has been prepared by specialists from one of the leading international laboratories, and illustrates with colour photographs typical resistance phenotypes associated with most known genes for resistance to the three rust diseases of wheat. Relevant details for each gene include chromosome location, aspects of genetics and pathogen variation, the effects of environment on expression, origin, availability in genetic and breeding stocks, and use in agriculture. This atlas includes an introduction to host:pathogen genetics, methodologies for wheat rust research and breeding for resistance.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Stem rust, caused by Puccinia graminis f. sp. tritici, has successfully prevented rust epidemics by Deployment of resistant cultivars in the past several decades. Unfortunately, race TTKS (termed Ug99) has defeated most stem rust resistance genes existing in commercial cultivars. Sr40, a stem rust resistance gene from Triticum timopheevii ssp. araraticum, was transferred to wheat and provides effective levels of seedling and adult plant resistance against Ug99. To characterize Sr40 in wheat, two mapping populations were developed from the crosses RL6088 / Lakin and RL6088 / 2174. RL6088 is an Ug99-resistant parent with Sr40. Since race TTKS is a quarantined pathogen, a US stem rust isolate RKQQ that is avirulent to Sr40 was used to evaluate the rust resistance in the F[subscript]2 and F[subscript]2:3 populations at the seedling stage. A total of 83 simple sequence repeats (SSR) primers on chromosome 2B were used to screen the parents for polymorphism. Each F[subscript]2 population was analyzed with the markers polymorphic between two parents. Marker Xwmc344 was the most closely linked to Sr40, at 0.7 cM proximal, in the linkage map constructed from the population RL6088 / Lakin, while Xwmc474 and Xgwm374 were also tightly linked. Xwmc474 was mapped 2.5 cM proximal to Sr40 in the RL6088 / 2174 population. Xwmc474 and Xwmc661 were flanking markers for Sr40 in both populations. Markers linked to Sr40 will be useful for marker-assisted integration of Sr40 into elite wheat breeding lines. In addition, a unknown stem rust resistance gene from another source, OK01307, a breeding line from Oklahoma State University shows partial resistance to Ug99, and was characterized using SSRs in this study. Two mapping populations were developed from cross OK01307 / Chinese Spring and OK01307 / LMPG-6. A total of 1300 SSR primers were screened for polymorphism between OK01307 and Chinese spring, and 1000 SSR primers were screened for polymorphism between OK01307 and LMPG-6. Polymorphic primers between parents and between bulks were used to screen the corresponding population. One Sr gene in OK01307 was mapped on chromosome 1BS of the both populations, which was closely linked to Sr24. Whether the gene is Sr24 per se or a new Sr gene that closely linked to Sr24 needs further investigation.

Author: Lu Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 193

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Stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst), is one of the most devastating and economically important diseases across major wheat growing regions in the world. Growing resistant cultivars is the most effective and environmentally sound method for controlling the disease. This study was conducted to identify resistance genes/QTL in three winter wheat cultivars Madsen, Skiles and Eltan and develop molecular markers for marker-assisted selection. Madsen has shown high-level and durable resistance since its release in 1988 and was identified to have both all-stage resistance (ASR) and high-temperature adult-plant (HTAP) resistance. Two major effect ASR QTL on chromosome arms 1AS and 2AS, one minor ASR QTL on 1BS and two HTAP resistance QTL on 3BS and 6BS were identified in Madsen. Skiles is susceptible to all tested Pst races at seedling stage but shows strong resistance at adult-plant stage with higher resistance level expressed at high temperature, indicating that Skiles has only HTAP resistance against the tested Pst races. Six HTAP resistance QTL were mapped in Skiles, with two major QTL mapped on 3BS and 4BL and four minor QTL on 1BL, 5AL, 6B and 7DL. Markers linked to the QTL were used to select highly resistant breeding lines derived from crosses with Skiles. Eltan has shown variable reactions from moderate susceptibility to resistance in different years since its release in 1990. Five QTL were detected in Eltan, with two major ASR QTL on 2BS and 4BL, one minor ASR on 5BS and two minor HTAP resistance QTL on 6AS and 7BL. The two major ASR QTL became less effective due to the fact that the Pst population has changed to virulent, leading to the resistance reduction in Eltan. By studying these three wheat cultivars with different genes for different types of resistance, it is concluded that the best strategy to achieve high-level and durable resistance is to combine several genes for effective ASR and adequate HTAP resistance. These studies provide the information of useful genes and molecular markers for improving resistance to stripe rust in wheat cultivars.