scholarly journals Characterization of Synthetic Wheat Line Largo for Resistance to Stem Rust

2021 ◽  
Author(s):  
Jyoti Saini Sharma ◽  
Megan Overlander ◽  
Justin D Faris ◽  
Daryl L Klindworth ◽  
Matthew N Rouse ◽  
...  
Keyword(s):  
Stem Rust ◽  
Recombinant Inbred Lines ◽  
Resistance Breeding ◽  
Synthetic Hexaploid Wheat ◽  
Genetic Linkage Analysis ◽  
Wheat Line ◽  
Wheat Stem Rust ◽  
Wheat Varieties ◽  
Seedling Resistance ◽  
Sr Genes

Abstract Resistance breeding is an effective approach against wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt). The synthetic hexaploid wheat line Largo (pedigree: durum wheat ‘Langdon’ × Aegilops tauschii PI 268210) was found to have resistance to a broad spectrum of Pgt races including the Ug99 race group. To identify the stem rust resistance (Sr) genes, we genotyped a population of 188 recombinant inbred lines developed from a cross between the susceptible wheat line ND495 and Largo using the wheat Infinium 90 K SNP iSelect array and evaluated the population for seedling resistance to the Pgt races TTKSK, TRTTF, and TTTTF in the greenhouse conditions. Based on genetic linkage analysis using the marker and rust data, we identified six quantitative trait loci (QTL) with effectiveness against different races. Three QTL on chromosome arms 6AL, 2BL, and 2BS corresponded to Sr genes Sr13c, Sr9e, and a likely new gene from Langdon, respectively. Two other QTL from PI 268210 on 2DS and 1DS were associated with a potentially new allele of Sr46 and a likely new Sr gene, respectively. Additionally, Sr7a was identified as the underlying gene for the 4AL QTL from ND495. Knowledge of the Sr genes in Largo will help to design breeding experiments aimed to develop new stem rust-resistant wheat varieties. Largo and its derived lines are particularly useful for introducing two Ug99-effective genes Sr13c and Sr46 into modern bread wheat varieties. The 90 K SNP-based high-density map will be useful for identifying the other important genes in Largo.

scholarly journals Mapping and Validation of Stem Rust Resistance Loci in Spring Wheat Line CI 14275

2021 ◽  
Vol 11 ◽  
Author(s):  
Zennah C. Kosgey ◽  
Erena A. Edae ◽  
Ruth Dill-Macky ◽  
Yue Jin ◽  
Worku Denbel Bulbula ◽  
...  
Keyword(s):  
Spring Wheat ◽  
Stem Rust ◽  
Rust Resistance ◽  
Recombinant Inbred Lines ◽  
The United States ◽  
Stem Rust Resistance ◽  
Adult Plant ◽  
Wheat Line ◽  
Seedling Resistance ◽  
Resistance Qtl

Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) remains a constraint to wheat production in East Africa. In this study, we characterized the genetics of stem rust resistance, identified QTLs, and described markers associated with stem rust resistance in the spring wheat line CI 14275. The 113 recombinant inbred lines, together with their parents, were evaluated at the seedling stage against Pgt races TTKSK, TRTTF, TPMKC, TTTTF, and RTQQC. Screening for resistance to Pgt races in the field was undertaken in Kenya, Ethiopia, and the United States in 2016, 2017, and 2018. One gene conferred seedling resistance to race TTTTF, likely Sr7a. Three QTL were identified that conferred field resistance. QTL QSr.cdl-2BS.2, that conferred resistance in Kenya and Ethiopia, was validated, and the marker Excalibur_c7963_1722 was shown to have potential to select for this QTL in marker-assisted selection. The QTL QSr.cdl-3B.2 is likely Sr12, and QSr.cdl-6A appears to be a new QTL. This is the first study to both detect and validate an adult plant stem rust resistance QTL on chromosome arm 2BS. The combination of field QTL QSr.cdl-2BS.2, QSr.cdl-3B.2, and QSr.cdl-6A has the potential to be used in wheat breeding to improve stem rust resistance of wheat varieties.

scholarly journals Characterization of Wheat Monogenic Lines with Known Sr Genes and Wheat Lines with Resistance to the Ug99 Race Group for Resistance to Prevalent Races of Puccinia graminis f. sp. tritici in China

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 1939-1943
Author(s):  
Xian Xin Wu ◽  
Qiu Jun Lin ◽  
Xin Yu Ni ◽  
Qian Sun ◽  
Rong Zhen Chen ◽  
...  
Keyword(s):  
Food Security ◽  
Stem Rust ◽  
Adult Plant ◽  
Puccinia Graminis ◽  
Wheat Cultivars ◽  
Wheat Stem Rust ◽  
Wheat Improvement ◽  
Wheat Lines ◽  
Sr Genes

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is one of the most serious fungal diseases in wheat production, seriously threatening the global supply of wheat and endangering food security. The present study was conducted to evaluate wheat monogenic lines with known Sr genes to the most prevalent P. graminis f. sp. tritici races in China. In addition, wheat lines introduced from the International Maize and Wheat improvement Center (CIMMYT) with resistance to the Ug99 race group were also evaluated with the prevalent Chinese P. graminis f. sp. tritici races. The monogenic lines containing Sr9e, Sr21, Sr26, Sr31, Sr33, Sr35, Sr37, Sr38, Sr47, and SrTt3 were effective against races 21C3CTTTM, 34C0MRGSM, and 34C3MTGQM at both seedling and adult-plant stages. In contrast, monogenic lines containing Sr6, Sr7b, Sr8a, Sr9a, Sr9b, Sr9d, Sr9f, Sr9g, Sr13, Sr16, Sr18, Sr19, Sr20, Sr24, Sr28, Sr29, and Sr34 were highly susceptible to these races at both seedling and adult-plant stages. Lines with Sr5, Sr10, Sr13, Sr14, Sr15, Sr17, Sr21, Sr22, Sr23, Sr25, Sr27, Sr29, Sr30, Sr32, Sr36, and Sr39 were resistant to one or more of the tested races. Among the 123 CIMMYT lines, 38 (30.9%) showed varying levels of susceptibility to Chinese P. graminis f. sp. tritici races. The results should be useful for breeding wheat cultivars with resistance to stem rust.

Stabilizing selection in Puccinia graminis tritici in Canada

1976 ◽  
Vol 54 (19) ◽  
pp. 2204-2214 ◽  
Author(s):  
Mishael Oichoe Osoro ◽  
G. J. Green
Keyword(s):  
Field Experiment ◽  
Stem Rust ◽  
Virulence Genes ◽  
Spore Production ◽  
Stabilizing Selection ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Wheat Varieties ◽  
Competitive Abilities ◽  
Field Plots

Experiments were designed to show whether or not virulence genes reduce fitness and bring about stabilizing selection. The competitive abilities of seven related races of Puccinia graminis f. sp. tritici were studied on seedlings of three to five susceptible wheat varieties by growing mixtures of the races in greenhouses, growth cabinets, and field plots. In experiments in which simple races with few virulence genes were mixed with complex races with one, two, or three extra virulence genes, the complex races predominated after 4 to 10 generations in five of the six mixtures, and the simple race predominated in one mixture. A complex race predominated over simple races in the field experiment. It was concluded that virulence genes did not impair the fitness of the wheat stem rust races studied.In one race mixture studied in growth cabinets the complex race predominated at 25 °C, and the simple race, at 15 °C. Temperature did not differentially influence the competitive abilities of the races in three other mixtures.Incubation periods for all races were shorter at higher temperatures, but races C18(15B-1L) and C33(15B-1L) developed faster than races C9(15B-1L), C37(15), C38(15B-1L), C42(15), and C49(15) at all temperatures. In addition, races C18(15B-1L) and C33(15B-1L) produced more urediospores per pustule than races C9(15B-1L), C37(15), and C49(15). The differences in incubation period and spore production are considered to be the most important factors studied and they could cause the differences in aggressiveness of the seven races.

scholarly journals Mapping and Characterization of a Wheat Stem Rust Resistance Gene in Durum Wheat “Kronos”

2021 ◽  
Vol 12 ◽  
Author(s):  
Hongna Li ◽  
Lei Hua ◽  
Matthew N. Rouse ◽  
Tianya Li ◽  
Shuyong Pang ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Resistance Genes ◽  
Stem Rust ◽  
Rust Resistance ◽  
Wheat Variety ◽  
Wheat Breeding ◽  
Stem Rust Resistance ◽  
Wheat Stem Rust ◽  
Seedling Resistance ◽  
Or Gene

Wheat stem (or black) rust is one of the most devastating fungal diseases, threatening global wheat production. Identification, mapping, and deployment of effective resistance genes are critical to addressing this challenge. In this study, we mapped and characterized one stem rust resistance (Sr) gene from the tetraploid durum wheat variety Kronos (temporary designation SrKN). This gene was mapped on the long arm of chromosome 2B and confers resistance to multiple virulent Pgt races, such as TRTTF and BCCBC. Using a large mapping population (3,366 gametes), we mapped SrKN within a 0.29 cM region flanked by the sequenced-based markers pku4856F2R2 and pku4917F3R3, which corresponds to 5.6- and 7.2-Mb regions in the Svevo and Chinese Spring reference genomes, respectively. Both regions include a cluster of nucleotide binding leucine-repeat (NLR) genes that likely includes the candidate gene. An allelism test failed to detect recombination between SrKN and the previously mapped Sr9e gene. This result, together with the similar seedling resistance responses and resistance profiles, suggested that SrKN and Sr9e may represent the same gene. We introgressed SrKN into common wheat and developed completely linked markers to accelerate its deployment in the wheat breeding programs. SrKN can be a valuable component of transgenic cassettes or gene pyramids that includes multiple resistance genes to control this devastating disease.

scholarly journals Disease Resistance Evaluation of Elite CIMMYT Wheat Lines Containing the Coupled Fhb1 and Sr2 Genes

Plant Disease ◽  
2020 ◽  
Vol 104 (9) ◽  
pp. 2369-2376
Author(s):  
Xinyao He ◽  
Gurcharn S. Brar ◽  
David Bonnett ◽  
Susanne Dreisigacker ◽  
Jessica Hyles ◽  
...  
Keyword(s):  
Stem Rust ◽  
Selection Process ◽  
Recombinant Inbred Lines ◽  
Resistance Breeding ◽  
Wheat Breeding ◽  
Head Blight ◽  
Phenotypic Marker ◽  
Repulsion Phase ◽  
Speed Up ◽  
Wheat Lines

Fusarium head blight (FHB) and stem rust are among the most devastating diseases of wheat worldwide. Fhb1 is the most widely utilized and the only isolated gene for FHB resistance, while Sr2 is a durable stem rust resistance gene used in rust-prone areas. The two loci are closely linked on the short arm of chromosome 3B and the two genes are in repulsion phase among cultivars. With climate change and the shift in Fusarium populations, it is imperative to develop wheat cultivars resistant to both diseases. The present study was dedicated to developing wheat germplasm combining Fhb1 and Sr2 resistance alleles in the International Maize and Wheat Improvement Center (CIMMYT)’s elite cultivars’ backgrounds. Four recombinant inbred lines (RILs) in Hartog background that have the resistant Fhb1 and Sr2 alleles in coupled phase linkage were crossed with seven CIMMYT bread wheat lines, resulting in 208 lines. Molecular markers for both genes were employed in addition to the use of pseudo-black chaff (PBC) as a phenotypic marker for the selection of Sr2. At various stages of the selection process, progeny lines were assessed for FHB index, Fusarium damaged kernels (FDK), stem rust, and PBC expression as well as other diseases of interest (stripe rust and leaf spotting diseases). The 25 best lines were selected for CIMMYT’s wheat breeding program. In addition to expressing resistance to FHB, most of these 25 lines have an acceptable level of resistance to other tested diseases. These lines will be useful for wheat breeding programs worldwide and potentially speed up the resistance breeding efforts against FHB and stem rust.

scholarly journals Physical Mapping of Stem Rust Resistance Gene Sr52 from Dasypyrum villosum Based on ph1b-Induced Homoeologous Recombination

2019 ◽  
Vol 20 (19) ◽  
pp. 4887 ◽  
Author(s):  
Li ◽  
Dong ◽  
Ma ◽  
Tian ◽  
Qi ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Stem Rust ◽  
Rust Resistance ◽  
Distal Segment ◽  
Stem Rust Resistance ◽  
Dasypyrum Villosum ◽  
Wheat Stem Rust ◽  
Wheat Varieties ◽  
Stem Rust Resistance Genes ◽  
Chromosome Segments

Wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt) had been a devastating foliar disease worldwide during the 20th century. With the emergence of Ug99 races, which are virulent to most stem rust resistance genes deployed in wheat varieties and advanced lines, stem rust has once again become a disease threatening global wheat production. Sr52, derived from Dasypyrum villosum and mapped to the long arm of 6V#3, is one of the few effective genes against Ug99 races. In this study, the wheat–D. villosum Robertsonian translocation T6AS·6V#3L, the only stock carrying Sr52 released to experimental and breeding programs so far, was crossed with a CS ph1b mutant to induce recombinants with shortened 6V#3L chromosome segments locating Sr52. Six independent homozygous recombinants with different segment sizes and breakpoints were developed and characterized using in situ hybridization and molecular markers analyses. Stem rust resistance evaluation showed that only three terminal recombinants (1381, 1380, and 1392) containing 8%, 22%, and 30% of the distal segment of 6V#3L, respectively, were resistant to stem rust. Thus, the gene Sr52 was mapped into 6V#3L bin FL 0.92–1.00. In addition, three molecular markers in the Sr52-located interval of 6V#3L were confirmed to be diagnostic markers for selection of Sr52 introgressed into common wheat. The newly developed small segment translocation lines with Sr52 and the identified molecular markers closely linked to Sr52 will be valuable for wheat disease breeding.

REPRODUCTIVE POTENTIALS OF RACES 15B AND 56 OF WHEAT STEM RUST

1967 ◽  
Vol 45 (7) ◽  
pp. 1077-1091 ◽  
Author(s):  
K. Katsuya ◽  
G. J. Green
Keyword(s):  
Incubation Period ◽  
Stem Rust ◽  
Selection Pressure ◽  
Field Conditions ◽  
Puccinia Graminis ◽  
Western Canada ◽  
Stages Of Development ◽  
Wheat Stem Rust ◽  
Wheat Varieties ◽  
Infection Density

Variations in the prevalence of races 56 and 15B-1 (Can.) of wheat stem rust (Puccinia graminis Pers. f. sp. tritici Erikss. and Henn.) have occurred that cannot be explained by changes in the wheat varieties grown in Western Canada. The reasons for the changes in prevalence were investigated by comparing in growth cabinets the reproductive potentials or aggressiveness of the two races and the factors that might influence them. When a mixture of urediospores of the two races was used to inoculate three susceptible varieties for successive uredial generations, race 56 predominated at 25 and 20 °C, and race 15B-1 (Can.) predominated at 15 °C. Experimentation showed that the urediospores of race 56 were more infective than those of 15B-1 (Can.) and that the incubation period of race 56 was shorter than that of race 15B-1 (Can.). Pustules of race 56 grew faster than those of race 15B-1 (Can.) during early stages of development but those of 15B-1 (Can.) ultimately became larger than those of race 56. Race 56 produced more urediospores per pustule than race 15B-1 (Can.) on the susceptible varieties Little Club, Red Bobs, and Marquis at 15 and 20 °C. Infection density markedly affected competitive abilities. Race 56 tended to predominate in light infections but race 15B-1 (Can.) tended to predominate in heavy infections. Pustule size decreased as infection density increased. The possible significance of these findings under field conditions is discussed. It seems likely that the rise of race 15B-1 (Can.) to predominance in 1950 resulted not only from the selection pressure of the widely grown varieties that were resistant to race 56 and susceptible to 15B-1 (Can.) but from the lower temperatures that prevailed and favored 15B-1 (Can.) over 56. The rise to predominance of race 56 from 1956 to 1961 may have resulted from the greater aggressiveness of that race under the moderate or warm conditions that prevailed.

scholarly journals Distribution, Epidemics dynamics and physiological races of wheat stem rust (Puccinia graminis f.sp. tritici Eriks and E. Henn) on irrigated wheat in the Awash River basin of Ethiopia

2021 ◽  
Author(s):  
Nurhussein Seid Yesuf ◽  
Sileshi Getahun ◽  
Shiferaw Hassen ◽  
Yoseph Alemayehu ◽  
Kitessa Gutu Danu ◽  
...  
Keyword(s):  
River Basin ◽  
Stem Rust ◽  
Seasonal Distribution ◽  
Wheat Stem Rust ◽  
Awash River Basin ◽  
Irrigated Wheat ◽  
Production Areas ◽  
Virulence Spectrum ◽  
Sr Genes ◽  
Race Analysis

ABSTRACTWheat is one of the high value important major crops of the globe. However, wheat stem rust is considered one of the determinant threats to wheat production in Ethiopia and the globe. So this study was conducted with the objective to assess disease intensity, seasonal distribution dynamics, and genetic variability and to determine virulence spectrum of stem rust in the irrigated wheat areas of Ethiopia. A total of 137 wheat farms were evaluated from 2014/15 - 2019/20 in six districts of Awash River basin. Farm plots were assessed every 5 - 10 km interval with ‘X’ fashion, and data on disease incidence, severity, and healthy plants were scored with diseased wheat plant samples collection for stem rust race analysis. The seasonal trend of wheat stem rust disease was also compared to see the future importance of the diseases. The result revealed that the prevalence, incidence, and severity of stem rust were significantly varied among the different districts and seasons in the two regions. The survey results also indicated that about 71.7% of the wheat fields were affected by stem rust during the 2018/19 growing season. The overall incidence and mean severity of the disease during the same season were 49.02% and 29.27%, respectively. During 2019/20 about 63.7% of the wheat fields were affected by stem rust, which, however, the incidence (30.97%) and severity (17.22%) were lower than the previous season. Although the seasonal disease distribution was decreased, its spatial distribution was expanding into Lower Awash. The physiological and the genetic race analysis identified four dominant races (TTTTF, TKTTF TKKTF, and TTKTF) during 2018/19 and additional race (TKPTF) during 2019/20. Thus races are highly virulent and affect most of the Sr genes except Sr – 31 and Sr – 24. TTTTF and TKKTF are the widest virulence spectrum which affects 90% of the Sr genes. Thus, it can be concluded that the spatial and seasonal distribution of the disease was expanding. Moreover, most of the races were similar with rain-fed production, and thus care must be given for effective management of the diseases to both agro-ecologies. Therefore, these findings provide inputs or insight for breeders to think about the breeding programs in their crossing lines and wheat producers to reduce the damage of the disease in the irrigated ecologies.ETHICAL STATEMENTThus, surveys were conducted with the lateral aim of rust epidemics early warning and monitoring support program in the Awash River basin. Samples for this study were collected from farmers’ fields of the irrigated production areas in the Awash River basin. The disease was an air-borne disease that is difficult to contain. Still, we give maximum care during surveying through spore-free through self-sanitation after Pgt infested field observation to minimize induced disease dissemination to the communities in the production areas that no specific permissions were required for these locations. Field sites are on public access, and P. graminis f. sp. tritici is already an air-born pathogen that doesn’t need special protection kinds. This work was our study experience in the endeavor in irrigated wheat technology dissemination.

scholarly journals Principal approaches and achievements in studying race composition of wheat stem rust

2019 ◽  
Vol 22 (8) ◽  
pp. 967-977 ◽  
Author(s):  
A. S. Rsaliyev ◽  
Sh. S. Rsaliyev
Keyword(s):  
Stem Rust ◽  
Wheat Stem Rust ◽  
Wheat Varieties ◽  
Differential Set ◽  
Northern Regions ◽  
Disease Agent ◽  
Commercially Important ◽  
New Races ◽  
Intraspecies Structure

 Wheat stem rust caused by the biotrophic fungus Puccinia graminis f. sp. tritici is a dangerous disease that seriously damages the economics in many countries of the world. The review contains information about epidemics of wheat stem rust and causes of their emergence worldwide. Recently wheat stem rust epidemics have been recorded in the northern regions of Kazakhstan and on the territories adjacent to Omsk Region of Russia. It has been shown that severe wheat stem rust epidemics occur mainly due to the emergence of new virulent races of the disease agent and to growing susceptible wheat cultivars. New methods of studying the race composition of the fungus are described as well as the use of the previous and current differential sets for race determination of P. graminis f. sp. tritici. The results of developing molecular markers and assessing their effectiveness in studying stem rust races are presented. Wheat stem rust races dominant in major grain-growing countries of the globe and their typical peculiarities are described. The paper contains information on identifcation of race Ug99 and of its variations including data on areas of their dissemination and on their virulence to Sr-resistance genes. The existence and emergence of other races of the agent potentially dangerous for commercially important genes for stem rust resistance is also described. Currently in nature strongly virulent races of P. graminis f. sp. tritici are circulating with wide geographical coverage and their virulence is absolutely different from the virulence of race Ug99. Historical and modern data on studying the race composition of the pathogen in Kazakhstan are summarized. It is stated that the use of the old standard differential set and an incomplete North American system of race nomenclature in experiments prevents measuring similarity between Kazakhstani races and the worldwide known races of the pathogen. It has been shown that there is a need to continue studies on the intraspecies structure of the disease agent’s population in Kazakhstan with the use of the modern differential set, on determination of race composition and ways of emergence of new races potentially dangerous for commercial wheat varieties.

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