All BGRI Abstracts

Displaying 1 - 10 of 415 records | 1 of 42 pages

Genetics of stem rust resistance in South African winter wheat varieties

BGRI 2018 Poster Abstract
Martin Chemonges University of the Free State
Liezel Herselman, Botma Visser, Willem Boshoff, Zacharias Pretorius

Most South African winter wheat varieties display all stage resistance (ASR) to stem rust caused by Puccinia graminis f. sp. tritici (Pgt). To study inheritance, four resistant varieties were crossed to a susceptible parent (Line 37) and F2 populations were phenotyped at the seedling stage with stem rust race PTKST (Ug99 lineage). Populations derived from varieties Koonap, Komati, Limpopo and SST 387 segregated in a 3:1 ratio, indicating that a single, dominant gene confers resistance in each population. Assessment of F2 seedlings of four intercrosses between these varieties failed to deliver susceptible segregants therefore suggesting that they carry the same resistance gene. Genotyping of F2 plants with microsatellite markers produced consistent linkage of resistance with markers on chromosome 6DS. Experiments are underway to determine the relationship between resistance in the four winter wheat varieties and resistance genes Sr42, SrCad and SrTmp, all located on 6DS. Current evidence shows that ASR in the South African winter wheat varieties Koonap, Komati, Limpopo and SST 387 is based on a single gene and thus vulnerable to pathogenic adaptation in Pgt.

Tags:

Stem rust resistance in durum wheat

BGRI 2018 Poster Abstract
Pablo Olivera University of Minnesota
Ayele Badebo, Worku Bulbula, Matthew Rouse, Yue Jin

Our research objective is to identify new resistance genes in durum wheat that are effective against TTKSK and other significant stem rust pathogen races that could be utilized in durum breeding. We characterized 8,000 accessions for stem rust response in the field (Debre Zeit, Ethiopia, and St. Paul, MN). Accessions with resistant to moderately resistant responses in multiple field evaluations were evaluated at the seedling stage for resistance to races TTKSK, TRTTF, TTTTF, JRCQC, TKTTF, and six representative U.S. races. We identified 438 durum accessions resistant to moderately resistant in all field evaluations. Among the field-resistant accessions, 273 were resistant to all races used in seedling evaluations. Accessions susceptible at the seedling stage are being evaluated for the presence of adult plant resistance genes. The highest frequencies of resistant lines include landraces from East and North Africa (Ethiopia and Egypt) and advanced breeding lines and cultivars from North America (Mexico and USA). DNA markers will be performed to identify the presence of durum stem rust resistance genes, including Sr13, Sr8155B1, Sr11, and Sr8a. Nineteen resistant accessions were selected to investigate the genetics of TTKSK and TRTTF resistance. Results from evaluating F2 and F2:3 generations from biparental crosses revealed that resistance to race TTKSK was conferred mostly by one or two genes with dominant and recessive actions. Additional resistance genes were identified when populations were evaluated against race TRTTF. A bulk segregant analysis approach is being used to map the resistance in selected lines using the 90K SNP platform.

Tags:

GENETIC MAPPING OF SEEDLING AND ADULT PLANT RESISTANCE FOR STRIPE RUST IN SPRING BREAD WHEAT (TRITICUM AESTIVUM L.)

BGRI 2018 Poster Abstract
Yewubdar Isehtu Ethiopian Institute of Agricultural Research (EIAR)

Stripe rust caused by Puccinia striiformis f.sp.tritici, is one of the major diseases of wheat in the world. Experiments were carried out at two sites in Ethiopia (Kulumsa and Meraro) during the 2015 cropping season to evaluate the response of 198 elite bread wheat genotypes and two checks to the prevailing races of stripe rust at adult plant and seedling stage. The genetic profile of these genotypes was assessed using 13006 SNP markers and an association mapping was explored to determine marker?trait association. About 72.5% and 42.5% of the lines exhibited resistance at Kulumsa and Meraro, respectively. Out of 198 genotypes tested in the greenhouse, 31% exhibited common resistance for Kubsa and mixed stripe rust isolate. Only 8966 of the SNPs were polymorphic, only these were used for association mapping analysis. These markers spanned an average density of 3.47 cM per marker, with the poorest density on the D genome. Almost half of these markers were on known chromosomes, but had no position on the consensus map of bread wheat. Analysis of population structure revealed the existence of three clusters and the estimated genomic wide Linkage Disequilibrium (LD) decay in this study ranged from 0 to 50 cM. 53 SNPs in ten genomic regions located on wheat chromosome 1AL, 2AL, 2BL, 2DL, 3BL, 4BL, 4DL, 5AS, 7AL and 7BL were identified. Thirty nine SNP markers in five genomic regions at Kulumsa and 14 SNP markers in six genomic regions at Meraro explained more than 25.5% and 35.1% of phenotypic variability respectively. For seedling stage, 21 markers in ten genomic regions located on wheat chromosomes 1B, 2A, 2B, 3A, 3B, 4B, 4D, 5A, 6B and 7B were associated with resistant. These loci may be useful for choosing parents and incorporating new resistance genes into locally adapted cultivars.

Tags:

Improvement of drought and salt tolerance of wheat genotypes under field conditions by high throughput precision phenotyping

BGRI 2018 Poster Abstract
Magdi Abdelhamid National Research Centre
Ibrahim El-Metwally

Food crisis is a major concern in Egypt, where drought and saline soils are ubiquitous. Wheat is a staple food in Egypt, which is only moderately tolerant to drought and salinity. Due to its rapidly increasing demand, there is an urgent need in Egypt to enhance wheat yields under drought and salinity conditions. Improving salinity or/and drought tolerance of genotypes is inhibited by a lack of efficient evaluation methods. High throughput precision phenotyping provides an innovative technology to screen for enhanced salt or drought tolerance from a large of number of genotypes under field conditions and can have immediate value to plant breeding. Therefore, we have tested several wheat phenotyping techniques i.e., canopy temperature (CT), spectral reflectance (SR), chlorophyll content (SPAD value), crop ground cover, relative water content (RWC), Water soluble carbohydrates (WSC), leaf area index (LAI), crop morphological traits, and grain wheat yield and yield components. We documented strong correlation/linear regression/polynomial regression between the wheat phenotyping techniques and in-season biomass/grain yield. It could be concluded that the documented results confirmed that several landraces were selected as drought/salinity tolerant out of 762 wheat landraces wheat were screened. Using high throughput precision phenotyping could provide an innovative technology and can have immediate value to plant breeding.

Tags:

Development of bread wheat cultivars for resistance to stem rust for cultivation in north zone of Iran

BGRI 2018 Poster Abstract
Manoochehr Khodarahmi Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Kamal Shahbazi, Jabbar Alt Jafarby, Mohammad Sadegh Khavarinejad, Farzad Afshari, Farshad Bakhtiar, Habibollah Soghi

In this project to obtain resistant wheat breeding lines/cultivars to stem rust disease, new cultivars and lines of the north breeding program were evaluated in greenhouse with races collected in 2014 from northern regions of Iran, Moghan and Gorgan. Artificial inoculation in greenhouse indicated none of the races had virulence on Sr11, Sr13, Sr24, Sr25, Sr26, Sr27, Sr29, Sr31, Sr32, Sr33, Sr37, Sr39, Sr40, and SrTmp. In order to evaluate seedling resistance, 143 wheat cultivars and new lines under greenhouse conditions were inoculated with four isolates of stem rust in four separate experiments in a randomized complete block design with three replications. Evaluation of the northern germplasm under greenhouse conditions showed that some of the genotypes were resistant against all four isolates. The resistance of some of these new lines was also confirmed in Kenya. Regarding other desirable agronomic characteristics, some of these lines will be introduced as new cultivars in the northern region of Iran.

Tags:

Easy method to select plants with two effective leaf rust resistance genes from wheat hybrid populations

BGRI 2018 Poster Abstract
Lev Tyryshkin All-Russian Institute of Plant Genetic Resources

Wheat varieties with single effective gene for leaf rust resistance often quickly become susceptible because of multiplication of virulent Puccinia triticina genotypes. One of the methods to elongate term of effectiveness is to combine two genes in host genotype. To note, it is impossible to distinguish phenotypically plants or families having one or two genes in hybrid populations; the only method is to use PCR producing DNA markers linked to each gene for resistance. It is not convenient when necessary to analyze thousands plants or especially families of crosses between carriers of certain genes. At inoculation of wheat seedlings having Lr 9, 19, 24, 47, 29 and Sp with rust population from North-West region of Russian Federation all of them were absolutely resistant, so these genes may be considered to be effective in this region. Rust population was multiplied on cv. Leningradka leaf segments placed on cotton wool wetted with solution of maleic acid hidrazide (10 mg/l) + potassium chloride (0.48 g/l) +monosubstituted sodium phosphate (0.66 g/l) and used to infect seedling of the lines constantly poured with the solution. Rare pustules were recorded on each line. Isolates from the line were combined, multiplied and used to infect the lines set. Interaction specificity was shown for carriers of certain genes for resistance and inoculums. We propose to infect seedlings of hybrid wheat populations with mixtures of isolates virulent to first gene and those virulent to second one at use of above-mentioned method to multiply rust and grow plants. Seedlings resistant to that inoculum have both genes for resistance. If we have F3 or later families it is possible to use original population without selection of virulent isolates; in this case the method allowed removing progenies of heterozygous plants. With this approach we developed lines possessing combinations of Lr9+Lr24 and Lr9+Lr47 genes

Tags:

Virulence diversity of wheat stem rust (Puccinia graminis f.sp. tritici) in Ethiopia in 2016 main cropping season

BGRI 2018 Poster Abstract
Endale Hailu Abera Ethiopian institute of agricultural research
Dr. Netsanet B. Heyi, Dr. Getaneh W. Wolderufael, Tsegab T.

Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is a major production constraint in most wheat growing areas of Ethiopia. The stem rust pathogen is capable of rapidly developing new virulence to resistance genes. The highlands of Ethiopia are considered a hot spot for Pgt diversity. The present study was conducted to investigate the virulence diversity and spatial distribution of races of Pgt in the major wheat growing areas of Ethiopia. The physiologic races of Pgt were determined on seedlings of the standard wheat stem rust differentials following the international system of nomenclature. Stem rust race analyses were carried out both at Ambo Plant Protection Center and the Cereal Disease Laboratory in Minnesota. 426 stem rust samples were collected from major wheat growing of the country in the 2016 cropping season and 185 viable samples were analyzed. Stem rust races TKTTF, TTKSK, TTTTF, JRCQC and RRTTF were identified. Among the identified races, TKTTTF was dominant at a frequency of 78.7% followed by TTKSK (10.6%). Race TTTTF was found for the first time in Ethiopia in 2016. Only one resistance gene in the differential set, Sr24, was effective against all isolates. Stem rust resistance gene Sr31 was found to confer resistance to most of the races prevalent in Ethiopia with the exception of Ug99. Sr24 could be used in combination with other resistance genes in breeding for resistance to stem rust in Ethiopia.

Tags:

Functional genomics of thermal stress tolerance in Indian wheat

BGRI 2018 Poster Abstract
Paramjit Khurana University of Delhi South Campus, New Delhi

Towards understanding the molecular mechanisms of heat stress tolerance, we have analyzed heat stressed substractive cDNA libraries and undertaken genome-wide transcriptome exploration for genes associated with spike photosynthetic efficiency during thermal stress. The photosynthetic efficiencies of Aegilops tauschii and Ae. speltoides were also compared. While the former displayed nearly complete recovery of PSII, the adverse effect was more pronounced in the latter. Functional characterization of heat stress-associated transcription factors and thermal stress-associated proteins was also undertaken e.g. TaHSF, TabZIP, TaZnF and TaMIPS, and TaLTPs in the Indian wheat germplasm. Functional characterization of the three heat stress transcription factors was upregulated under high temperatures and other abiotic stresses. They also showed early flowering and better performance with respect to their growth and yield after heat stress. Additionally, we have identified various interacting components associated with thermal stress-mediated plant signaling partners during thermal stress.

Tags:

Gone with the wind: Revisiting stem rust dispersal between southern Africa and Australia

BGRI 2018 Poster Abstract
Botma Visser Department of Plant Sciences, University of the Free State, South Africa
Marcel Meyer, Robert Park, Christopher Gilligan, Laura Burgin, Matthew Hort, David Hodson, Zacharias Pretorius

Despite being 10,000 km apart, the current study emphasizes the potential vulnerability of Australia to wind-borne Puccinia graminis f. sp. tritici (Pgt) spore introductions from southern Africa. Of four Pgt introductions into Australia since 1925, at least two (races 326-1,2,3,5,6 and 194-1,2,3,5,6) are thought to have originated from southern Africa. Microsatellite analysis of 29 Australian and South African Pgt races confirmed close genetic relationships between the majority of races in these two geographically separated populations, thus supporting previously reported phenotypic similarities. Using Lagrangian Particle Dispersion Model simulations with finely-resolved global meteorological data over a 14-year period and a three-day urediniospore survival time, the study showed that long distance dispersal of Pgt from southern Africa to Australia is possible, albeit rare. Transmission events occurred most frequently from central South Africa, but were also possible from southern South Africa and Zimbabwe; while none occurred from a representative source-location in Tanzania. Direct dispersal incursions into both the western and eastern Australian wheat belts were feasible. Together, the genetic and simulation data strongly support the hypothesis that earlier introductions of Pgt into Australia occurred through long-distance wind-dispersal across the Indian Ocean. The study thus acts as a warning of possible future Pgt dispersal events to Australia which could include members of the Ug99 race group. This emphasizes the continued need for Pgt surveillance on both continents.

Tags:

EMS derived changes in susceptibility to P. triticina in wheat.

BGRI 2018 Poster Abstract
John Fellers USDA-ARS HWWGRU

P. triticina has a biotrophic relationship with wheat and needs certain elements from the wheat host for a successful life cycle. In recent years, several long lasting, minor resistance genes have been cloned, and their function suggests that the resistance is not due to a classic NB-LRR gene, but a gene that functions in a biotrophic pathway. The hypothesis was proposed that modification of a susceptibility gene can provide broad, long lasting resistance. To test this hypothesis, Thatcher was treated with EMS and screened for changes in susceptibility. M5 lines were evaluated in the greenhouse with BBBD Race 1 and 5 lines were identified. Also, M5 lines were planted in the field to verify the resistance and test the resistance effectiveness to natural infections of P. triticina. The same five lines were resistant in the field. Resistance ranged from few pustules, a race specific-like reaction, lesion mimics with few or no pustules, and near immunity. These lines were backcrossed to Thatcher, and resistant F2 plants were bulked and sequenced. Gene candidates will be identified and discussed.

Tags:

Pages