All BGRI Abstracts

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

Targeting stem rust resistance genes Sr32 and Sr1644 for cloning by mutagenesis and sequence capture

BGRI 2015 Poster Abstract
Wulff John Innes Centre, UK

Resistance offers the best means of control of the cereal rusts, but must be strategically deployed so as to avoid exposure of single major genes, which have faltered so many times in the past. The pyramiding of multiple effective resistance genes is a strategy that has proven effective in a number of wheat production areas around the world. However, the process of incorporating multiple resistance genes into a single cultivar using standard breeding techniques is time consuming, laborious, and hampered by the problem of linkage drag. If a suite of effective resistance genes could be efficiently cloned and transferred into wheat as a cassette, it would accelerate the development of durably resistant varieties without the problem of linkage drag. Toward this end, we have developed a resistance gene cloning technology based on resistance gene enrichment sequencing (RenSeq) of EMS-derived mutant R gene alleles. As a proof of concept test, we successfully ‘re’-cloned the already characterized gene Sr33 and are now targeting the cloning of eight other effective resistance genes. For the identification of susceptible mutants for the cloning of Sr32 from Aegilops speltoides, we screened 1,109 M2 families with race TPMKC — as a surrogate for race TTKSK. Five susceptible M2 mutants were confirmed by progeny testing. These mutants were also susceptible to race TTKSK. For the population involving Sr1644 from Ae. sharonensis, 1,649 M2 families were screened, yielding 33 M2 families that appeared to segregate for susceptibility. Thirteen of 33 families were confirmed as bona fide susceptible mutants by progeny tests in the M3 generation. Identification of susceptible EMS mutants of Sr32 and Sr1644 suggests that the underlying resistance in these lines is conferred by single genes. We will report on progress to clone and characterize these genes using R gene exome capture and sequencing technology (RenSeq).

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Resistance to wheat stem rust in selected accessions of Iranian wheat landraces

BGRI 2015 Poster Abstract
Mojerlou Tarbiat Modares University of Tehran, Iran
View mojerlou.pdf (199.61 KB)

Stem rust is a potentially destructive fungal disease of wheat worldwide. In 1998 Pgt pathotype TTKSK virulent to Sr31 was detected in Uganda. The same pathotype was confirmed in Lorestan and Hamedan provinces of Iran in 2007. We used a derivative of race TTKSK to phenotype 62 Iranian wheat landraces (resistant to stripe rust in a previous study) at the seedling stage to this new pathotype (TTSSK). Twenty eight accessions were evaluated for the presence of resistance genes Sr2, Sr22, Sr24, Sr25, Sr26, Sr35, Sr36 and Srweb using SSR markers. None carried Sr2, Sr24 or Sr26, but the presence of Sr22, Sr25, Sr35 and Sr36 was indicated. Some susceptible landraces predicted to carry Sr2 by marker analysis require further investigation. To evaluate defense gene expression in compatible and incompatible stem rust interactions we sampled resistant and susceptible cultivars at 0, 12, 18, 24, 72 hours post-inoculation (hpi). ?-1,3 glucanase expression was studied using qGLU-S and qGLUU-AS primers and a real-time PCR step-one ABI machine, with ?-tubulin and EF1-? genes used as internal controls. In incompatible interactions defense gene expression was increased at 24 hpi, but in compatible interactions the highest level of expression occurred at 12 hpi and was significantly decreased at 18 hpi. The results revealed that expression of defense genes such as ?-1,3 glucanase was earlier in compatible than in incompatible interactions but the expression level was less in incompatible interactions. On the other hand, in susceptible genotypes the expression of defense genes increased immediately after inoculation and declined sharply after infection. In contrast defense gene expression in resistant genotypes began to increase after establishment of the pathogen.

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Performance of CIMMYT germplasm in Ethiopia: Key materials for variety development

BGRI 2015 Poster Abstract
Abeyo CIMMYT-Ethiopia

CIMMYT wheat germplasm flow to Ethiopia started in the late 1960s. Over 90 bread wheat varieties were released over the decades. Of these, about 77% had CIMMYT origins or were derived from CIMMYT materials. Wheat is a traditional rainfed crop grown by 5 million small-scale farmers on 1.6 ha more or less. Yields have increased from 1.0 t/ha in the 1960s to 2.54 t/ha in 2014 mainly due to high yielding semi-dwarf bread wheat varieties and modern agronomic practices. Using such technologies, better farmers often get 5-6 t/ha. The rusts are the most important production constraints. For example, the 2010 yellow rust epidemic debilitated the mega varieties Kubsa and Galama in the highlands. In 2013/14, stem rust caused up to 100% yield losses in the widely adopted bread wheat variety Digalu in Arsi and Bale. This epidemic was caused by Pgt race TKTTF, which is virulent to the gene SrTmp that is present in Digalu, but is avirulent to Sr31, which is overcome by race Ug99 (TTKSK) and derivatives. To avert the increasing threat of rusts, CIMMYT developed a shuttle breeding program where germplasm moves back and forth between Mexico and Kenya and has increased nursery testing sites (Holetta, Kulumsa, Debre Zeit, Sinana, Adet, and Melkassa) in Ethiopia from two to six. The germplasm passes through rigorous tests against major diseases during both the main- and off-seasons. To obtain high yielding rust resistant germplasm, many hundreds of genotypes were introduced and tested over the last two years. In 2014/15, 266 (25%) lines with multiple disease resistances and high yield were promoted to national trials. CIMMYT continues to be an important source of germplasm. Fast tracked variety testing and release, accelerated seed multiplication, demonstration and popularization of new varieties with high yield, multiple disease resistance, and acceptable quality will continue.

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Evaluation of wild wheat introgression lines for rust resistance and yield

BGRI 2015 Poster Abstract
Abugaliyeva Kazakh Research Institute of Agriculture and Plant Growing

Wild species are sources and donors of many valuable traits for wheat improvement. We studied winter wheat introgression lines for productivity traits, disease resistance, and protein, globulin, gliadin and glutenin contents as well as grain mineral concentrations. Laboratory and field studies allowed selection in populations segregating for resistance to yellow rust and leaf rust. Lines 1718, 1721-9, 1721-4, 1675 and 1727 had the highest yields (6.2 t/ha) and stable leaf rust and stem rust resistances, but were still variable in response to stripe rust (30-80 S). Lines 1718 (Bezostaya 1 x Ae. cylindrica, genomes CCDD) and 1721 (Bezostaya 1 x T. militinae2 - 6, ABG) were resistant to stripe rust in trials at yield levels of 3.7-7.6 t/ha and from 5.7 to 8.2 t/ha, respectively. Line 1675 (Zhetisu x T. kiharae, ABGD) was resistant to all three rusts. Line 1676 (Steklovidnaya 24 x T. timopheevi, ABG) was resistant to LR and SR at a yield level of 8.3 t/ha, and 1671 (Zhetisu x T. militinae, ABG) was resistant to YR and SR at a yield level of 7.5 t/ha. Protein contents of the lines ranged from 13.6 to 18.4%, and grain mineral contents were above average.

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Surveillance and Pgt race analysis in Iran, 2014

BGRI 2015 Poster Abstract
Afshari Seed and Plant Improvement Institute (SPII), Iran

Stem (black) rust is a potentially important disease in northern, western and southern Iran. A new Pgt race with virulence to gene Sr31 appeared in Iran in 2007. Similar races have spread in Africa and some CWANA countries. In 2014 stem rust was widespread in western, northern, northwestern and central Iran, but at low severities. Thirty-nine stem rust samples were collected for race analysis. After purification and increase each isolate was inoculated to a set of 20 North American differentials in the greenhouse. Infection types were recorded 12-14 days after inoculation using the scale described by McIntosh et al. (1995, Wheat Rusts: An Atlas of Resistance Genes, CSIRO, East Melbourne, Australia). Races TKSTC (59%), TKTTC (20%), TTTTC, KTTSK (virulent on plants with Sr31), TTSTC, PTTTF and TTTTF were detected. Race TKSTC was common in western, northwestern and central Iran. Except for avirulence to Sr17 this race is similar to the race (TKTT) that caused a stem rust epidemic in Ethiopia in 2013.

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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 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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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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