All BGRI Abstracts

Displaying 21 - 30 of 197 records | 3 of 20 pages

Rust reactions of lines in a wheat crossing block developed by the Bahri Dagdas International Agricultural Research Institute in 2014

BGRI 2015 Poster Abstract
Akan The Central Research Institute for Field Crops, Turkey

Rusts and drought are the principal yield-limiting factors for wheat production in the Central Anatolian region of Turkey. The aim of the study was to determine resistance sources in a crossing block of drought tolerant lines. Seedling tests involving all three rusts were carried out at CRIFC, Yenimahalle, in 2014. Inoculations were made with local Pgt (avirulent on differentials with Sr24, Sr26, Sr27 and Sr31), Pt (avirulent on differentials with Lr9, Lr19, Lr24 and Lr28) and a local Pst population. Reactions were scored 14 days post-inoculation on 0-4 (LR and SR) or 0-9 (YR) scales. Seventeen (19%) genotypes were resistant to stripe rust, 11 (12%) were resistant to leaf rust, and 17 (19%) were resistant to stripe rust.

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Comparative analysis of rust resistant and susceptible wheat varieties in Pakistan

BGRI 2015 Poster Abstract
Ali International Maize and Wheat Improvement Center (CIMMYT) Pakistan Office

To reduce losses caused by rusts, regular and timely replacement of susceptible varieties with new high yielding, rust resistant varieties must occur. Data from a farmer survey carried out across Pakistan (Punjab, Sindh, KPK and Baluchistan) in 2014 enabled an analysis of the uptake of rust resistant variety NARC 2011. The empirical results indicated that the major sources of information that farmers obtained about NARC 2011 were research stations (83%), seed companies (7%) and fellow farmers (5%). Although production inputs were applied equally to both rust resistant NARC 2011 and rust susceptible wheat varieties the average yield of NARC 2011 (5,063 kg/ha) was superior to high yielding but rust susceptible varieties (4,446 kg/ha). Quality attributes of NARC 2011, including taste, color, dough kneading and chapatti making properties, were preferred by >70% of farmers). Seed availability and accessibility of NARC 2011 were major issues. Farmer awareness of rusts, especially the threat of exotic Pgt race Ug99, needs to be improved.

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Rust responses of some Turkish, white grained, bread wheat genotypes in preliminary yield trials

BGRI 2015 Poster Abstract
Akan Central Research Institute for Field Crops, Turkey

Bread wheat is the most important cereal crop in Turkey. Rusts (caused by Puccinia spp.) are the most significant diseases affecting wheat yield and quality on the Central Anatolian Plateau. The purpose of this study was to identify the reactions of 198 Turkish, white seeded, winter wheat genotypes developed by the Central Research Institute for Field Crops (CRIFC) and entered in preliminary yield trials. Adult plant and seedling tests were conducted for stripe rust whereas only seedling tests were conducted for leaf rust and stem rust. Evaluations were carried out at CRIFC, İkizce and Yenimahalle, in the 2014 season. For adult plant stripe rust assessments the materials were inoculated with a local Pst population (virulent on differentials carrying Yr2, Yr6, Yr7, Yr8, Yr9, Yr25, Yr27, YrSd, YrSu, and YrA). Stripe rust development on each entry was scored using the modified Cobb scale when the susceptible check Little Club had reached 80S in June 2014. Coefficients of infection were calculated and values below 20 were considered to be resistant. Seedlings were inoculated with local Pgt (avirulent on differentials with Sr24, Sr26, Sr27 and Sr31), Pt (avirulent on differentials with Lr9, Lr19, Lr24 and Lr28) and the Pst population. Reactions were scored for each entry at 14 days post-inoculation on standard 0-4 (LR and SR) or 0-9 (YR) scales. At the seedling stage, 56 (28%), 43 (22%), and 31 (31%) genotypes were resistant to SR, LR and YR, respectively. Eighty three (42%) lines were resistant to YR at the adult stage.

 

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Rust resistant spring wheats from Kazakhstan and Siberia: Genotype prediction as a basis for effective resistance breeding

BGRI 2015 Poster Abstract
Akhmetova CIMMYT-Kazakhstan

Northern Kazakhstan and Western Siberia are major high latitude spring wheat growing regions on the Eurasian continent. Rust epidemics can cause serious crop losses in this region. For this purpose, the Kazakhstan-Siberian network for wheat improvement (KASIB) was created in 2000. Seventy wheat cultivars and lines from a KASIB nursery were characterized for seedling and adult plant resistance (APR) to leaf rust using Australian pathotypes in greenhouse and field experiments. A molecular marker (STS iag95) detecting 1RS and therefore genes located in the rye component of the 1BL.1RS translocation was used to verify the presence/absence of Lr26. Field assessments of the nursery were conducted at Cobbitty using mixed Pt pathotypes. Lr26 was detected in five cultivars (Bayterek, GVK-1916-9, Altayskaya 105, Ok-1, and Omskaya 36) based on seedling tests using seven pathotypes. This was confirmed using the SRS marker. Other genes postulated included Lr3a (in cv. GVK 1860/8, GVK 1369/2, GVK 1857/9, and GVK 1526-2) and uncharacterized gene/s in cv. Zhenis and Lutescens-166 SP 94). The majority of KASIB entries were susceptible in seedling tests to Pt, but varying levels of potentially useful resistance were observed in 23 genotypes tested in the field. Low infection types on seedlings and field resistance in cv. Tertsia, Aria, and Sonata suggested the presence of unknown gene/s of potential value that warrant further investigation. Future efforts to breed wheat varieties resistant to one or more of the cereal rust pathogens will require identification of resistance sources that differ from those already present. Understanding the dynamics of pathogenic variability in pathogen populations is also important in selecting appropriate resistances.

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Complementary resistance genes Yr73 and Yr74 (YrA) in wheat selection Avocet R confer resistance to the non-adapted barley grass stripe rust pathogen Puccinia striiformis f. sp. pseudohordei.

BGRI 2015 Poster Abstract
Dracatos The University of Sydney, Plant Breeding Institute, Australia

This is the first study on the inheritance and genetic mapping of resistance to the barley grass stripe rust pathogen (Puccinia striiformis f. sp. pseudohordeiPsph) in bread wheat. Psph, commonly infects barley grass (Hordeum leporinum, H. murinum), but about 10% of commercial barley varieties are also susceptible. We tested over 500 diverse wheat accessions and determined that less than 20% were susceptible at the seedling stage suggesting wheat is an ‘intermediate’ host to Psph. The Australian variety Teal is highly susceptible to Psph at the seedling stage, whereas selections Avocet S and Avocet R are highly resistant and resistant, respectively. We used the Teal/AvocetR doubled haploid (DH) population to characterize the resistance of Avocet R to Psph and determine whether the complementary genes Yr73 and Yr74 (YrA resistance) in Avocet R conferred resistance to Psph. Phenotypic comparison of the Teal/AvocetR DH lines in response to both Psph and Pst showed that all DH lines carrying YrA were also resistant to Psph; however, fewer DH lines were susceptible to Psph suggesting additional resistance genes. Marker-trait association analysis detected three DArT-Seq markers significantly associated with resistance to Psph, two mapping to chromosomes 3DL and 5BL in the same regions as Yr73 and Yr74 and the third mapping to chromosome 4A. Single gene stocks with the 4A gene and combinations of the 5BL and 3DL genes will be used for monitoring avirulence/virulence within Australian Psph population. Genetic analysis of seedling-susceptible T/AvR DH lines as adult plants in the greenhouse determined that Teal and Avocet R each carried at least one APR gene effective against Psph.

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Identification of markers closely linked with adult plant leaf rust resistance gene Lr48 in wheat

BGRI 2015 Poster Abstract
Vallence Nsabiyera The University of Sydney, Plant Breeding Institute, Australia

Leaf rust is endemic to all wheat-growing regions of the world. Resistance to leaf rust in wheat cultivars is controlled either by all stage resistance (ASR) or by adult plant resistance (APR) genes. Although deployment of single ASR genes can provide high levels of resistance, these are usually overcome by virulence in pathogen populations. In contrast, individual APR genes often provide low levels of resistance and combinations of three to four genes are necessary to achieve adequate resistance for crop protection. This kind of APR has proven to be durable. APR gene Lr48 in a single plant selection of Condor (CSP44) was mapped on chromosome 2BS and was flanked by markers gwm429b (6.1 cM, distal) and barc7 (7.3 cM, proximal) (Bansal et al. 2008, Theor. Appl. Genet. 117:307-312). The present study was planned to identify markers more closely linked to Lr48. Selective genotyping by 90K Infinium Assay identified 27 SNP markers linked with Lr48. The SNP sequences were used to design Kompetitive Allele-Specific Primers (KASP). Eleven KASP markers showing clear clustering were genotyped on a RIL population using the CFX96 Touch™ real-time PCR detection system (Biorad, USA). KASP marker IWB72894 co-segregated with Lr48.

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Molecular mapping of resistance to the Pgt race Ug99 group in spring wheat landrace PI 177906

BGRI 2015 Poster Abstract
Babiker USDA-ARS, Small Grains and Potato Germplasm Research Unit, USA
View babiker.pdf (941.79 KB)

Wheat landrace PI 177906 has seedling and field resistance to Pgt races TTKSK and TTKST. From a cross between PI 177906 and LMPG-6, 138 doubled haploid (DH) lines and 144 recombinant inbred lines (RILs) were developed and tested for seedling resistance to Pgt race TTKSK. Goodness-of-fit tests from both populations indicated that two dominant genes in PI 177906 conditioned resistance to race TTKSK. Parents and the 138 DH lines were evaluated in the field in two experiments in Kenya; one in the main season and one in the off-season. The 90K wheat iSelect SNP genotyping platform was used to genotype the parents and DH lines and data were used to construct a genetic linkage map. Two loci for seedling resistance were mapped to chromosomes 2BL and 4BL. Two major QTL for field resistance mapped to the same regions, a 14.4 cM interval on 2BL and an 8.5 cM interval on 4BL. The QTL on 2BL and 4BL explained, respectively, 31.9-32.3% and 18.2-19.1% of the variation in the off-season and 28.3-30.4% and 5.4-6.5% of the variation in the main-season. Based on the mapping results, race specificity, and the seedling infection types, the resistance gene in 2BL could be Sr28, whereas the gene on chromosome 4BL could be novel. The mapping results will be verified in the RIL population using the flanking SNP markers in KASP assays.

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Rapid detection of micro-RNAs associated with APR to rust pathogens in wheat

BGRI 2015 Poster Abstract
Singh The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, Australia

The identification of R-genes using traditional map-based approaches is a long, laborious process, not to mention the time required for subsequent development of cultivars incorporating the new resistances. Breeders seek to reduce the length of breeding cycles, and researchers require new tools to accelerate discovery and understanding of mechanisms associated with durable resistance, especially adult plant resistance (APR). A new method for rapid generation advancement, known as ‘speed breeding’, significantly reduces the length of breeding cycles, provide increased recombination during line development and enable selection in early generations. The speed breeding protocol uses controlled temperature regimes and 24h light to accelerate plant growth and development. Phenotyping methods adapted for use in the speed breeding system permit year-round evaluation of APR to rust pathogens within 5 weeks from time of sowing. RNA sequencing (RNA-Seq) technology has revolutionized gene expression profiling in plants. We previously used RNAseq to identify novel transcripts and miRNAs associated with seedling resistance (Lr28) leading to identification of transcription factors and miRNA families (e.g. miR36, miR37 and miR39) involved in signalling and defense response (Kumar et al. J. Nuc. Acids 2014:570176). In this study we report the application of speed breeding and RNAseq technologies for the purpose of rapidly identifying transcripts and miRNA associated with APR. Wheat landraces harbouring novel sources of resistance were grown under speed breeding conditions and sampled for RNA at key growth stages, before and after inoculation, which enabled discovery of differentially expressed miRNAs. Our next steps are aimed at validating these genetic factors associated with APR in order to better understand the signalling pathways and deliver tools to assist the assembly of robust wheat cultivars for the future.

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Reactions of spring wheat genotypes in crossing block nursery to stem, leaf, and stripe rust

BGRI 2015 Poster Abstract
Mert The Central Research Institute for Field Crops, Turkey

Rusts (Puccinia spp.) are the most significant disease affecting wheat yield and quality in Turkey. Knowing the resistance status of wheat genotypes in crossing program is an important issue for breeding programs. The aim of the study was to determine of the resistance of the 106 wheat genotypes consisting of Crossing Block Spring Wheat (CBSW) nursery developed by the International Winter Wheat Improved Project (IWWIP). For this purpose, adult plant and seedling test were conducted for yellow rust while only seedling test were conducted for leaf and stem rust. Evaluations were carried out at the research facilities of CRIFC at İkizce and Yenimahalle in Ankara in the 2014 season. For adult plant reactions; the genotypes were inoculated with local Pst populations (virulent on Yr2,6,7,8,9,25,27,Sd,Su,Avs). Stripe rust development on each entry were scored using the modified Cobb scale when the susceptible check Little Club had reached 80S infection severity in June, 2014. Coefficients of infections were calculated and values below 20 were considered to be resistant. For seedling test; the seedling was inoculated with local Pgt (avirulent on Sr24, Sr26, Sr27, and Sr31), Pt (avirulent on Lr9, Lr19, Lr24, and Lr28) and Pst populations. Stripe, leaf and stem rust development on each entry were scored after 14 days with 0-4 and 0-9 scale for leaf-stem rust and yellow rust, respectively. In seedling stage, thirty nine (37%), 47 (44%), and 20 (19%) genotypes were resistant to local Pgt, Pt, and Pst populations, respectively. In adult plant test, 46 (43%) genotypes were resistant to Pst.  The resistance genotypes to stem, leaf, and stripe rust were determined with this research.

 

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The Stubbs Pst Culture Collection: Recovery, avirulence/virulence phenotyping and past population structure at a global scale

BGRI 2015 Poster Abstract
Thach Department of Agroecology, Aarhus University, Denmark

The "Stubbs Collection", began in 1956 by the late Dutch plant pathologist R.W. Stubbs, refers to a unique historic collection of urediniospore samples of Puccinia striiformis that had been stored in liquid nitrogen for decades. Since 2010 the collection has been maintained by the Global Rust Reference Center (GRRC) in Denmark. Part of the collection is now being in a study of past pathogen diversity. A subset of samples collected between 1958 and 1991 from 35 countries was investigated to assess recovery rate, race identity, and previously undetected virulences. A new method for recovery using an airbrush sprayer and NovecTM 7100 fluid as dispersal agent in inoculating host plants was highly successful, resulting in a 96% recovery from 231 isolates. Phenotyping on the World and European differential host sets and additional wheat genotypes revealed 181 apparently uniform isolates, of which race identities were confirmed for 102. Race identities were updated for additional isolates based on improved resolution due to updated and more informative differential lines. Additional virulences corresponding to Yr17, Yr25, and Yr27 were added, as these were not assayed earlier. The past population structure was investigated by genotyping 212 isolates using 19 multilocus microsatellites. Seven distinct populations were detected, including clonal populations and recombinant populations. These results were compared with recent studies and demonstrated an overall consistent population subdivision at the global scale with clear migration events between populations. The outcome of the study facilitates conclusions about long-term temporal dynamics and overall migration patterns within and among world-wide populations of Pst.

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