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Bergen auf Rügen, Germany

Miedaner T.,University of Hohenheim | Korzun V.,KWS LOCHOW GMBH
Phytopathology | Year: 2012

Marker-assisted selection (MAS) provides opportunities for enhancing the response from selection because molecular markers can be applied at the seedling stage, with high precision and reductions in cost. About each of 50 genes conferring monogenic resistances and hundreds of quantitative trait loci (QTL) for quantitative disease resistances have been reported in wheat and barley. For detecting single-major gene resistance, MAS could beeasily applied, but is often not necessary because the resistances are selected phenotypically. In quantitative disease resistances, MAS would be very useful, but the individual QTL often have small effects. Additionally, only a few monogenic resistances are durable and only a few QTL with high effects have been successfully transferred into elite breeding material. Further economic and biological constraints, e.g., a low return of investment in small-grain cereal breeding, lack of diagnostic markers, and the prevalence of QTL-\ background effects, hinder the broad implementation of MAS. Examples in which MAS has been successfully applied to practical breeding are the wheat rust resistance genes Lr34 and Yr36, the eyespot resistance gene Pch1, the recessive resistance genes rym4/ rym5 to barley yellow mosaic viruses, mlo to barley powdery mildew, and two QTL for resistance to Fusarium head blight in wheat (Fhb1 and Qfhs.ifa-5A). Newly identified broad-spectrum resistance genes/QTL conferring resistance to multiple taxa of pathogens offer additional perspectives for MAS. In the future, chip-based, highthroughput genotyping platforms and the introduction of genomic selection will reduce the current problems of integrating MAS in practical breeding programs and open new avenues for a molecularbased resistance breeding.

Miedaner T.,University of Hohenheim | Schwegler D.D.,University of Hohenheim | Wilde P.,KWS LOCHOW GMBH | Reif J.C.,Leibniz Institute of Plant Genetics and Crop Plant Research
Theoretical and Applied Genetics | Year: 2014

Key message: We investigated associations between line per se and testcross performance in rye and suggested that selection for per se performance is valuable for several traits in multi-stage selection programs. Genotypic correlation between line per se and testcross performance is an important quantitative-genetic parameter for optimizing hybrid breeding programs. The main goal of this survey was to study the association of line per se and testcross performance at the phenotypic level. We used experimental data from the line per se and testcross performance of two segregating winter rye populations (A, B) with each of 220 progenies tested in six environments for eight agronomic and quality traits. Genotypic variances were considerably larger for per se than for testcross performance of all investigated traits resulting in higher heritabilities of the former in most instances. Genotypic correlations (r g) between testcross and line per se performance decreased with increasing complexity of the trait as shown by the respective heritabilities. They were highest (r g ≥ 0.7) for plant height and test weight in population B, and thousand-kernel weight, falling number and starch content in both populations. A selection of these traits for line per se performance in early generations will save field plots in further testing testcross performance and increase efficiency of hybrid breeding. © 2013 Springer-Verlag Berlin Heidelberg.

Wang Y.,Leibniz Institute of Plant Genetics and Crop Plant Research | Wang Y.,University of Hohenheim | Mette M.F.,Leibniz Institute of Plant Genetics and Crop Plant Research | Miedaner T.,University of Hohenheim | And 4 more authors.
BMC Genomics | Year: 2014

Background: Marker-assisted selection (MAS) and genomic selection (GS) based on genome-wide marker data provide powerful tools to predict the genotypic value of selection material in plant breeding. However, case-to-case optimization of these approaches is required to achieve maximum accuracy of prediction with reasonable input.Results: Based on extended field evaluation data for grain yield, plant height, starch content and total pentosan content of elite hybrid rye derived from testcrosses involving two bi-parental populations that were genotyped with 1048 molecular markers, we compared the accuracy of prediction of MAS and GS in a cross-validation approach. MAS delivered generally lower and in addition potentially over-estimated accuracies of prediction than GS by ridge regression best linear unbiased prediction (RR-BLUP). The grade of relatedness of the plant material included in the estimation and test sets clearly affected the accuracy of prediction of GS. Within each of the two bi-parental populations, accuracies differed depending on the relatedness of the respective parental lines. Across populations, accuracy increased when both populations contributed to estimation and test set. In contrast, accuracy of prediction based on an estimation set from one population to a test set from the other population was low despite that the two bi-parental segregating populations under scrutiny shared one parental line. Limiting the number of locations or years in field testing reduced the accuracy of prediction of GS equally, supporting the view that to establish robust GS calibration models a sufficient number of test locations is of similar importance as extended testing for more than one year.Conclusions: In hybrid rye, genomic selection is superior to marker-assisted selection. However, it achieves high accuracies of prediction only for selection candidates closely related to the plant material evaluated in field trials, resulting in a rather pessimistic prognosis for distantly related material. Both, the numbers of evaluation locations and testing years in trials contribute equally to prediction accuracy. © 2014 Wang et al.; licensee BioMed Central Ltd.

Whitford R.,University of Adelaide | Fleury D.,University of Adelaide | Reif J.C.,Leibniz Institute of Plant Genetics and Crop Plant Research | Garcia M.,University of Adelaide | And 3 more authors.
Journal of Experimental Botany | Year: 2013

Global food security demands the development and delivery of new technologies to increase and secure cereal production on finite arable land without increasing water and fertilizer use. There are several options for boosting wheat yields, but most offer only small yield increases. Wheat is an inbred plant, and hybrids hold the potential to deliver a major lift in yield and will open a wide range of new breeding opportunities. A series of technological advances are needed as a base for hybrid wheat programmes. These start with major changes in floral development and architecture to separate the sexes and force outcrossing. Male sterility provides the best method to block self-fertilization, and modifying the flower structure will enhance pollen access. The recent explosion in genomic resources and technologies provides new opportunities to overcome these limitations. This review outlines the problems with existing hybrid wheat breeding systems and explores molecular-based technologies that could improve the hybrid production system to reduce hybrid seed production costs, a prerequisite for a commercial hybrid wheat system. © The Author 2013. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved.

Li Y.,TU Munich | Haseneyer G.,TU Munich | Schon C.-C.,TU Munich | Ankerst D.,TU Munich | And 3 more authors.
BMC Plant Biology | Year: 2011

Rye (Secale cereale L.) is the most frost tolerant cereal species. As an outcrossing species, rye exhibits high levels of intraspecific diversity, which makes it well-suited for allele mining in genes involved in the frost responsive network. For investigating genetic diversity and the extent of linkage disequilibrium (LD) we analyzed eleven candidate genes and 37 microsatellite markers in 201 lines from five Eastern and Middle European rye populations.Results: A total of 147 single nucleotide polymorphisms (SNPs) and nine insertion-deletion polymorphisms were found within 7,639 bp of DNA sequence from eleven candidate genes, resulting in an average SNP frequency of 1 SNP/52 bp. Nucleotide and haplotype diversity of candidate genes were high with average values π = 5.6 × 10-3and Hd = 0.59, respectively. According to an analysis of molecular variance (AMOVA), most of the genetic variation was found between individuals within populations. Haplotype frequencies varied markedly between the candidate genes. ScCbf14, ScVrn1, and ScDhn1 were dominated by a single haplotype, while the other 8 genes (ScCbf2, ScCbf6, ScCbf9b, ScCbf11, ScCbf12, ScCbf15, ScIce2, and ScDhn3) had a more balanced haplotype frequency distribution. Intra-genic LD decayed rapidly, within approximately 520 bp on average. Genome-wide LD based on microsatellites was low.Conclusions: The Middle European population did not differ substantially from the four Eastern European populations in terms of haplotype frequencies or in the level of nucleotide diversity. The low LD in rye compared to self-pollinating species promises a high resolution in genome-wide association mapping. SNPs discovered in the promoters or coding regions, which attribute to non-synonymous substitutions, are suitable candidates for association mapping. © 2011 Li et al; licensee BioMed Central Ltd.

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