Genetic Mapping of the Common and Dwarf Bunt Resistance Gene Bt12 Descending From the Wheat Landrace PI119333

Common bunt (CB), caused by Tilletia caries and T. foetida, and dwarf bunt (DB), caused by T. controversa, are particularly destructive diseases of wheat grown under organic (low-input) production conditions and negatively affect both grain yield and quality. A total of 16 race specific bunt resistance genes have been proposed to date. Thereof, only Bt9 and Bt10 have been mapped so far. A mapping and two validation populations comprising 176 recombinant inbred lines were evaluated for CB and DB in artificially inoculated field trials. The mapping population was derived from the cross of the Bt12 carrier PI119333 and the susceptible cultivar ‘Rainer’. The population was genotyped with the Illumina 15 K SNP chip and the major QTL QBt.ifa-7DS representing Bt12 was identified on chromosome 7DS, explaining 39% and 14% of the phenotypic variation for CB and DB resistance, respectively. Selected SNP markers were turned into Kompetitive Allele-Specific (KASP) markers and used to validate Bt12 in two independent validation populations. These markers can be used for introgressing Bt12 into regionally adapted elite breeding material

Assessment of genetic diversity of wheat genotypes using microsatellite markers

Background and Purpose: Genetic diversity is the material basis for crop improvement. In this study, genetic diversity of 30wheat genotypeswas evaluated at theDNAlevel using 24 simple sequence repeat (SSRs) markers. Materials and Methods: DNA extraction was performed according to the modified CTAB-method. Microsatellite analysis was performed using fluorescent fragment detection on a LI-COR 4200 DNA. Results and Discussion: The number of alleles per locus ranged from 1 to 14 with an average number of 8.44 alleles per locus. The highest number of alleles per locus was detected in the genome A with 7.2, compared to 5.9 and 5.0 for genomes B and D, respectively. The highest number of alleles was recorded at chromosome 7 (9.5), while the lowest number of alleles was detected at chromosomes 3 and 4 (5.0 and 5.3). The smallest genetic distance characterized genotypes Super Zitarka and Zitarka, Tena and Osjecanka, Tena and Bezostaja, Lela and Toras, Janica and Alka, Felix and Seka.Genotypes Pipi and Courtot showed the least genetic similiarities with rest of the genotypes. Conclusions: The identification of genetic diversity should be a good tool of selecting genotypes in breeding programs

Assessment of genetic diversity of wheat genotypes using microsatellite markers

Background and Purpose: Genetic diversity is the material basis for crop improvement. In this study, genetic diversity of 30wheat genotypeswas evaluated at theDNAlevel using 24 simple sequence repeat (SSRs) markers. Materials and Methods: DNA extraction was performed according to the modified CTAB-method. Microsatellite analysis was performed using fluorescent fragment detection on a LI-COR 4200 DNA. Results and Discussion: The number of alleles per locus ranged from 1 to 14 with an average number of 8.44 alleles per locus. The highest number of alleles per locus was detected in the genome A with 7.2, compared to 5.9 and 5.0 for genomes B and D, respectively. The highest number of alleles was recorded at chromosome 7 (9.5), while the lowest number of alleles was detected at chromosomes 3 and 4 (5.0 and 5.3). The smallest genetic distance characterized genotypes Super Zitarka and Zitarka, Tena and Osjecanka, Tena and Bezostaja, Lela and Toras, Janica and Alka, Felix and Seka.Genotypes Pipi and Courtot showed the least genetic similiarities with rest of the genotypes. Conclusions: The identification of genetic diversity should be a good tool of selecting genotypes in breeding programs

Mapping of quantitative adult plant field resistance to leaf rust and stripe rust in two European winter wheat populations reveals co-location of three QTL conferring resistance to both rust pathogens

Key message We detected several, most likely novel QTL for adult plant resistance to rusts. Notably three QTL improved resistance to leaf rust and stripe rust simultaneously indicating broad spectrum resistance QTL. Abstract The rusts of wheat (Puccinia spp.) are destructive fungal wheat diseases. The deployment of resistant cultivars plays a central role in integrated rust disease management. Durability of resistance would be preferred, but is difficult to analyse. The Austrian winter wheat cultivar Capo was released in the 1989 and grown on a large acreage during more than two decades and maintained a good level of quantitative leaf rust and stripe rust resistance. Two bi-parental mapping populations: Capo × Arina and Capo × Furore were tested in multiple environments for severity of leaf rust and stripe rust at the adult plant stage in replicated field experiments. Quantitative trait loci associated with leaf rust and stripe rust severity were mapped using DArT and SSR markers. Five QTL were detected in multiple environments associated with resistance to leaf rust designated as QLr.ifa-2AL, QLr.ifa-2BL, QLr.ifa-2BS, QLr.ifa-3BS, and QLr.ifa-5BL, and five for resistance to stripe rust QYr.ifa-2AL, QYr.ifa-2BL, QYr.ifa-3AS, QYr.ifa-3BS, and QYr.ifa-5A. For all QTL apart from two (QYr.ifa-3AS, QLr.ifa-5BL) Capo contributed the resistance improving allele. The leaf rust and stripe rust resistance QTL on 2AL, 2BL and 3BS mapped to the same chromosome positions, indicating either closely linked genes or pleiotropic gene action. These three multiple disease resistance QTL (QLr.ifa-2AL/QYr.ifa-2AL, QLr.ifa.2BL/QYr.ifa-2BL, QLr.ifa-3BS/QYr.ifa.3BS) potentially contribute novel resistance sources for stripe rust and leaf rust. The long-lasting resistance of Capo apparently rests upon a combination of several genes. The described germplasm, QTL and markers are applicable for simultaneous resistance improvement against leaf rust and stripe rust. © 2014 The Author(s)

Processing-Structure-Property Relationships in Ni-based Superalloy René 41

The cast and wrought Nickel based superalloy René 41 combines excellent strength, toughness, and corrosion properties. Its mechanical properties outperform all similar competitor aerospace alloys such as Waspaloy and Haynes 282. However, processing of René 41 remains challenging due to cracking and inhomogeneous grain size distributions, resulting in poor yield, limiting more wide-spread application. Therefore, despite having been developed in the 1950s, René 41 is not yet widely applied, and published research is limited. However, trends towards higher efficiency aircraft engines have now reignited interest in René 41 as a candidate material in next generation engines due to its excellent property profile. This necessitates new research to reduce the knowledge gaps in the processing-microstructure-property relationships of René 41. Correlative high-resolution microscopy is successfully applied to identify previously ambiguous secondary phases in René 41. This approach reveals complete space group, as well as high quality compositional information. These insights are applied to the development of an experimental precipitation study, and to update a current thermodynamic database for superalloys. The updated database has improved predictive quality regarding phase stability and composition of the grain boundary carbides M6C and M23C6. Applying these results to kinetic simulations also demonstrates higher predictive power. Such improved simulations are required to optimize the precipitation behaviour and predict material properties after processing. Comparison to literature data shows that the updated database yields improvements for other alloys besides René 41 as well, such as Haynes 282, Waspaloy and alloys in the Nimonic series. Further, dynamic restoration processes are studied based on laboratory scale hot-working experiments. Targeted design of the temperature profiles, allows the effect of nm scale γ’ precipitates on microstructural evolution to be isolated. Implementing the gained insights in simulations and phenomenological models advances the capabilities of modern software tools, providing better insights into microstructural processes. The results presented in this thesis will thus advance the understanding of the microstructural evolution in René 41 and the descriptive capabilities of modern thermodynamic simulation packages. This will facilitate higher yield in processing and enable future alloy design for next generation aerospace applications

Transcriptomic characterization of two major Fusarium resistance quantitative trait loci (QTLs), Fhb1 and Qfhs.ifa-5A, identifies novel candidate genes

Fusarium head blight, caused by Fusarium graminearum, is a devastating disease of wheat. We developed near-isogenic lines (NILs) differing in the two strongest known F. graminearum resistance quantitative trait loci (QTLs), Qfhs.ndsu-3BS (also known as resistance gene Fhb1) and Qfhs.ifa-5A, which are located on the short arm of chromosome 3B and on chromosome 5A, respectively. These NILs showing different levels of resistance were used to identify transcripts that are changed significantly in a QTL-specific manner in response to the pathogen and between mock-inoculated samples. After inoculation with F. graminearum spores, 16 transcripts showed a significantly different response for Fhb1 and 352 for Qfhs.ifa-5A. Notably, we identified a lipid transfer protein which is constitutively at least 50-fold more abundant in plants carrying the resistant allele of Qfhs.ifa-5A. In addition to this candidate gene associated with Qfhs.ifa-5A, we identified a uridine diphosphate (UDP)-glycosyltransferase gene, designated TaUGT12887, exhibiting a positive difference in response to the pathogen in lines harbouring both QTLs relative to lines carrying only the Qfhs.ifa-5A resistance allele, suggesting Fhb1 dependence of this transcript. Yet, this dependence was observed only in the NIL with already higher basal resistance. The complete cDNA of TaUGT12887 was reconstituted from available wheat genomic sequences, and a synthetic recoded gene was expressed in a toxin-sensitive strain of Saccharomyces cerevisiae. This gene conferred deoxynivalenol resistance, albeit much weaker than that observed with the previously characterized barley HvUGT13248

Advanced backcross QTL mapping of resistance to Fusarium head blight and plant morphological traits in a Triticum macha × T. aestivum population

While many reports on genetic analysis of Fusarium head blight (FHB) resistance in bread wheat have been published during the past decade, only limited information is available on FHB resistance derived from wheat relatives. In this contribution, we report on the genetic analysis of FHB resistance derived from Triticum macha (Georgian spelt wheat). As the origin of T. macha is in the Caucasian region, it is supposed that its FHB resistance differs from other well-investigated resistance sources. To introduce valuable alleles from the landrace T. macha into a modern genetic background, we adopted an advanced backcross QTL mapping scheme. A backcross-derived recombinant-inbred line population of 321 BC2F3 lines was developed from a cross of T. macha with the Austrian winter wheat cultivar Furore. The population was evaluated for Fusarium resistance in seven field experiments during four seasons using artificial inoculations. A total of 300 lines of the population were genetically fingerprinted using SSR and AFLP markers. The resulting linkage map covered 33 linkage groups with 560 markers. Five novel FHB-resistance QTL, all descending from T. macha, were found on four chromosomes (2A, 2B, 5A, 5B). Several QTL for morphological and developmental traits were mapped in the same population, which partly overlapped with FHB-resistance QTL. Only the 2BL FHB-resistance QTL co-located with a plant height QTL. The largest-effect FHB-resistance QTL in this population mapped at the spelt-type locus on chromosome 5A and was associated with the wild-type allele q, but it is unclear whether q has a pleiotropic effect on FHB resistance or is closely linked to a nearby resistance QTL

Common bunt in organic wheat: unravelling infection characteristics relevant for resistance breeding

Common bunt caused by Tilletia tritici and T. laevis has re-emerged as a major threat to wheat yield and quality, especially in organic farming. Resistance against its causal agents is present in the wheat gene pool and provides the most economically efficient and sustainable way to combat the disease since seed treatments approved for organic farming are rare and do not always provide full protection. We tested a winter wheat diversity panel with 128 lines for common bunt resistance in Austria and Czechia, and evaluated the applicability of marker-assisted selection (MAS) via Kompetitive Allele-Specific PCR markers in genotypes with high variation in their genetic background. Field trials were conducted across two years and artificially inoculated with local bunt populations. The virulence patterns of these inocula differed between locations and only 15% of the tested genotypes showed stable resistance across test sites. Number and weight of bunt sori relative to the total number and weight of wheat grains in sampled ears revealed that partial infections of ears were frequently appearing. Forty-two breeding lines harboring combinations of four different resistance QTL were developed through MAS. Out of these, a quarter were resistant with a maximum of 5% common bunt incidence. On the other hand, only six out of 46 tested commercial cultivars and breeding lines showed no infection with common bunt, underlining the present scarcity of bunt-resistant cultivars for organic wheat production. By this study we showed that MAS is a useful tool to speed up the selection of resistant lines even in populations with highly diverse genetic backgrounds, and that it is efficient in pyramiding resistance loci and thereby improving the level of resistance

Suppressed recombination and unique candidate genes in the divergent haplotype encoding Fhb1, a major Fusarium head blight resistance locus in wheat

Fhb1 is a prominent Fusarium head blight resistance locus of wheat, which has been successfully introgressed in adapted breeding material, where it confers a significant increase in overall resistance to the causal pathogen Fusarium graminearum and the fungal virulence factor and mycotoxin deoxynivalenol. The Fhb1 region has been resolved for the susceptible wheat reference genotype Chinese Spring, yet the causal gene itself has not been identified in resistant cultivars. Here, we report the establishment of a 1 Mb contig embracing Fhb1 in the donor line CM-82036. Sequencing revealed that the region of Fhb1 deviates from the Chinese Spring reference in DNA size and gene content, which explains the repressed recombination at the locus in the performed fine mapping. Differences in genes expression between near-isogenic lines segregating for Fhb1 challenged with F. graminearum or treated with mock were investigated in a time-course experiment by RNA sequencing. Several candidate genes were identified, including a pathogen-responsive GDSL lipase absent in susceptible lines. The sequence of the Fhb1 region, the resulting list of candidate genes, and near-diagnostic KASP markers for Fhb1 constitute a valuable resource for breeding and further studies aiming to identify the gene(s) responsible for F. graminearum and deoxynivalenol resistance.(VLID)141383