Author: Hsiao-Yi Hung Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Mallorie Lewarne Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
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: Xiangyu (Bruce) Pei Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
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: RA McIntosh Publisher: CSIRO PUBLISHING ISBN: 0643103023 Category : Technology & Engineering Languages : en Pages : 308
Book Description
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: Bhoja Basnet Publisher: ISBN: Category : Languages : en Pages :
Book Description
Wheat (Triticum aestivum L.) is one of the most important food crops, comprising the largest source of daily calorie and protein intake of human beings worldwide. Among the several diseases of wheat, Yellow Rust (YR; caused by Puccinia striiformis Westend. f. sp. tritici) and Leaf Rust (LR; caused by Puccinia triticina Erikss. & Henn.) have always been major production constraints since the domestication of wheat. For the last few decades, scientists have invested large efforts to identify, characterize and utilize Adult Plant Resistance (APR), a.k.a. slow rusting resistance, in wheat germplasm to promote durability of resistance against rust. The objectives of this study were to 1) understand the genetics of APR to YR and/or LR present in two potential wheat lines 'Quaiu 3' and 'TAM 111', and 2) map the putative Quantitative Trait Loci (QTL) associated with YR and LR resistance using DNA-based molecular markers. Two Recombinant Inbred Line (RIL) populations were subjected to YR and LR disease evaluation experiments in multiple years and locations. Visual evaluation of Disease severity (DS) and Infection Type (IT) score in both RIL populations showed that APR to YR and LR were highly heritable quantitative traits with significant correlation among experiments. In spring wheat population, composite interval mapping consistently detected four and three large effect QTL for YR and LR resistance, respectively. Among those QTLs, 1B, 3B and 1D QTL were found to be associated with previously characterized genes Lr46/Yr29, Sr2/Yr30 and Lr42, respectively. However, QTLs QYr.tam-3D and QYr.tam-2D were potentially novel. The largest YR QTL QYr.tam-2D was located on long arm of chromosome 2D explaining about 48 to 61% of the total phenotypic variation. Similarly, in winter wheat population, apart from three environment-specific QTL on chromosomes 1A, 2A and 7D, the QTL on chromosome 2B (QYr.tam-2B) was found to express consistently in multiple environments explaining about 23 to 63% of total phenotypic variation. This study has further elucidated the inheritance mechanism of APR to YR and LR present in two different wheat lines, Quaiu 3 and TAM 111, and resulted in the successful mapping and characterization of the genetic loci associated with corresponding disease resistance traits. These findings should be very useful to isolate the novel APR genes and/or directly use in wheat breeding programs to enhance durable rust resistance in diverse wheat germplasm and cultivars in the future.
Author: Mina Rachelle Talajoor Publisher: ISBN: Category : Wheat Languages : en Pages : 152
Book Description
Wheat leaf rust, stem rust, and stripe rust are major fungal diseases of wheat caused by Puccinia triticina, P. graminis f. sp. tritici, and P. striiformis f. sp. tritici, respectively. Development of wheat varieties with genetic resistance to pathogens is a common strategy to protect against significant yield loss. However, incorporating resistance is not always straightforward, and understanding the mechanisms responsible for triggering host resistance is key. Here, were characterized two different genetic mechanisms involved in the rust resistance defense response in wheat. Two spring wheat cultivars and their respective EMS mutants, which displayed enhanced resistance to leaf, stem, and/or stripe rust, were studied. The cultivar Canthatch possesses a stem rust resistance suppressor on chromosome 7DL. We characterized the spectrum of resistance of Canthatch and the mutant CTH-NS, confirming the specificity of this suppressor is stem rust-specific. The cultivar Alpowa mutant MNR220 displays broad-spectrum resistance to a number of wheat rust races at the seedling stage. We characterized the functional resistance of MNR220 to a race of leaf rust by sampling inoculated tissues at various time points and tracking the disease progress microscopically. The mutant MNR220 confers resistance at the pre-haustorial stage; formation of haustoria is delayed or inhibited in MNR220 relative to the wild type Alpowa.
Author: Hsiao-Yi Hung
Author: Mallorie Lewarne
Author: Sewalem Amogne Mebrate
Author: Xiangyu (Bruce) Pei
Author: Seýýbastienne Constance Drijepondt
Author: 
Author: RA McIntosh
Author: Julia Xiuling Zhang
Author: Bhoja Basnet
Author: Mina Rachelle Talajoor