Verminderung von Alkaloiden in der Nahrungskette durch die züchterische Verbesserung der Mutterkorn-Resistenz von Winterroggen

Rye as an outcrossing crop is highly susceptible to ergot infection caused by Claviceps purpurea. It is ecologically the best solution to avoid the infection already in the field by growing resistant varieties. Aim of our study is the analysis of inheritance of self-fertile rye material for ergot resistance and alcaloid content. Sixty CMS inbred lines and their 90 CMS crosses were tested in pollen-isolated fields in three environ-ments under the conditions of Ecological Farming by artificial inoculation. The sclerotia weight per head was evaluated as resistance trait. Both, CMS lines and testcrosses showed significant genotypic differences at the individual environments. Correlation between both groups was significant (r=0,6-0,7; P=0,01). The alcaloid contents and the alcaloid spectra of 25 CMS lines revealed no genotypic difference. Breeding of self-fertile rye for a higher resistance to ergot should be successful on the long run

Genetic variation for resistance to ergot (Claviceps purpurea [Fr.] Tul.) in self-incompatible and self-fertile rye populations

Mutterkorn ist eine der bedeutendsten Ährenkrankheiten des Roggens. Der Mutterkornpilz (Claviceps purpurea [Fr.] Tul.) bildet bei Befall zur Blüte anstelle der Körner schwarze Über-dauerungsformen (Sklerotien), die eine Vielzahl von schädlichen Alkaloiden enthalten. In der vorliegenden Arbeit wurde unter angewandt-züchterischer Zielsetzung die genetische Variation zwischen und innerhalb selbstinkompatibler Roggenpopulationen für die Mutterkorn-Resistenz geschätzt. Ferner wurde die Resistenz von CMS-Linien und ihren Testkreuzungen gegen Mutterkorn unter Pollenisolation in mehreren Umwelten ermittelt. Zur Ermittlung der genetischen Variation zwischen selbstinkompatiblem Roggen wurden 2002 und 2004 an je zwei Standorten 65 Populationen auf Mutterkorn-Resistenz geprüft (Experiment 1). Darunter waren 13 zugelassene Populationssorten und 52 Genetische Ressourcen. Zur Schätzung der genetischen Variation innerhalb der Populationen (Experiment 2) wurden aus fünf ausgewählten Populationen jeweils 50 Vollgeschwisterfamilien (VGF) erstellt und in vier Umwelten (Jahr-Ort-Kombinationen) geprüft. Um genetische Unterschiede in der Anfälligkeit des Fruchtknotens und Blütenbodens nach Eindringen der Pilzsporen in das Innere der Blüte zu ermitteln, wurde in Experiment 3 ein Sortiment von 64 aktuellen CMS-Linien in den Jahren 2003 und 2004 sowie deren männlich-sterile Testkreuzungen mit drei Testern (= Sätze) im Jahr 2004 unter Pollenisolation angebaut. Alle Experimente wurden mit einem aggressiven Isolategemisch von Claviceps purpurea dreimalig während der Blüte inokuliert. Zur Minderung der Nachbarschaftseffekte wurden die Mikroparzellen schachbrettartig angeordnet und durch Anbau von Weizen voneinander getrennt. Alle Experimente wurden unter Bedingungen des Ökologischen Landbaus durchgeführt. Als Resistenzmerkmal dienten in Experiment 1 und 2 das Verhältnis der befallenen Ähren relativ zur Gesamtzahl der Ähren einer Parzelle und der Mutterkornanteil im Erntegut relativ zum Gesamterntegewicht der Parzelle. Die Pollenschüttung, ein entscheidendes morphologisches Merkmal für die unterschiedliche Anfälligkeit der Roggensorten gegenüber Mutterkorn, wurde durch eine Antherenbonitur auf einer Skala von 1-9 (1 = steril, 9 = vollstäubend) erfasst. Im Experiment 3 wurde das Gewicht der Mutterkörner pro Ähre (MKÄ) erfasst. Da die Inzuchtlinien sich erheblich in der Anzahl der Spindelstufen unterschieden, wurde zusätzlich das Gewicht der Mutterkörner je Spindelstufe (MKS) bestimmt. Für den Mutterkornanteil im Erntegut wurden bei den Roggenpopulationen signifikante genotypische und Genotyp-Umwelt-Interaktionsvarianzen festgestellt. Kein Genotyp war mutterkornfrei. Zwischen den zugelassenen Populationssorten und den Genetischen Ressourcen gab es im Mittel keinen Unterschied. Die genetische Variation innerhalb der Population war für alle fünf Populationen signifikant. Es fanden sich stets einzelne Nachkommen, die resistenter als das Populationsmittel waren. Das Mittel der Ausgangs-populationen unterschied sich kaum vom Mittel der jeweiligen Nachkommenschaft. Dies ist ein Hinweis auf die überwiegend additive Vererbung der Resistenz. Damit konnte erstmals an Züchtungspopulationen gezeigt werden, dass es innerhalb des selbstinkompatiblen Genpools genetisch bedingte Mutterkorn-Resistenz gibt. Aufgrund der gleichmäßig hohen Pollenschüttung sollte diese genotypische Varianz auf überwiegend physiologische Resistenzursachen zurückzuführen sein. Die 64 CMS-Linien zeigten unter Pollenisolation eine signifikante genetische Variation bezüglich der Mutterkorn-Resistenz. Die dazugehörenden Testkreuzungen hatten meist ein höheres Mutterkorngewicht/Ähre als ihre CMS-Linien. Zwischen den drei Testkreuzungsserien ergaben sich deutliche Unterschiede im Resistenzniveau. Dabei zeigten Kreuzungen mit Tester 1 die größte Mutterkornanfälligkeit, während die Kreuzungen mit Tester 2 kaum über dem Mittel der Elternlinien lagen. Alle Materialgruppen hatten eine quantitative Merkmalsverteilung. Für das Mutterkorngewicht/Ähre der Linien ergaben sich schwache bis mäßige Korrelationen zwischen den einzelnen Orten (0,33 ? 0,47). Bei den Testkreuzungen waren die Beziehungen zwischen den Orten noch schwächer. Zwischen den CMS-Linien und ihren Testkreuzungen waren mit Ausnahme von Satz 1 nur schwache Beziehungen für das Mutterkorngewicht/Ähre zu verzeichnen. Der Liniensatz I und die korrespondierenden Kreuzungen mit Tester 1 zeigten an beiden Standorten eine enge Beziehung für MKÄ (rp = 0,65). Die Schätzwerte der fehlerbereinigten Korrelationen lagen bei allen Materialgruppen höher als die der phänotypischen Korrelationen. Die auf den Alkaloidgehalt ihrer Sklerotien untersuchten CMS-Linien zeigten keine genetischen Unterschiede in diesem Merkmal. Die Studie zeigt, dass sowohl bei selbstinkompatiblem Roggen als auch im aktuellen Hybridzuchtmaterial genügend große genetische, quantitativ vererbte Variation für Mutterkorn-Resistenz vorhanden ist. Aufgrund der bedeutenden Genotyp × Umwelt-Interaktion können die Genotypen nur durch Prüfung in mehreren Umwelten eindeutig hinsichtlich ihrer Resistenz beurteilt werden. Eine Selektion auf erhöhte Mutterkornresistenz bei Roggen sollte langfristig erfolgreich sein.Ergot (Claviceps purpurea [Fr.] Tul.) is one of the most important diseases in rye. Infection during flowering results in the production of black, overwintering organs (sclerotia) instead of kernels, which contain harmful alcaloids. Three experiments were conducted to estimate quantitative-genetic parameters of the resistance of rye to ergot under the conditions of organic farming. The general aim was the estimation of genetic variation among and within self-incompatible rye populations and among CMS lines and their male-sterile testcrosses. In 2002 and 2004, genetic variation in resistance to ergot was tested among 65 rye populations at each of two locations (Experiment 1). Thirteen populations were registered rye varieties and the remaining 52 were genetic resources. To assess genetic variation within populations, 50 full-sib families (FSF) from each of five rye populations were developed and tested at four locations (Experiment 2). To test genetic differences in the susceptibility of ovaries towards fungal penetration in the absence of pollen, (i) 64 currently available CMS lines and (ii) their male-sterile crosses with three testers (=sets) were tested in 2003 and 2004, and in 2004, respectively. Inoculation was performed by spraying an aggressive mixture of isolates of Claviceps purpurea three times during the flowering period. The micro-plots were grown in a chess-board design separated by wheat plots to reduce the neighbouring effects. Traits of resistance were the proportion of infected spikes relative to the total number of spikes per plot, and the percentage by weight of ergot sclerotia in the grain. In Experiment 3, the weight of slcerotia per spike and per pair of spikelet were measured due to the absence of grain. Amount of pollen shedding was rated on the basis of the anther size and extrusion. Highly significant genotypic and genotype-environment interaction variances were found among rye populations in the percentage of ergot sclerotia in the grain. All genotypes were infected by ergot. No differences in mean among the registered rye varieties and genetic resources were detected. Because all populations were highly pollen shedding, the results indicate the existence of genetically determined resistance to ergot within the self-incompatible rye. Correlation between both resistance traits was significant (rp = 0.92). Genetic variation within populations was highly significant for all five populations. Individual progenies with resistance higher than the population mean were observed. The mean resistance of initial populations hardly differed from the mean of their progeny indicating a predominantly additive inheritance. Highly significant genetic variation in resistance to ergot was also detected among the currently available 64 CMS lines. Corresponding testcrosses mostly had a higher weight of sclerotia per spike than the lines. Considerable differences in the level of resistance were observed among testcrosses. Crosses with tester line 1 were substantially more susceptible, whereas those with tester 2 were hardly over the mean of the parental lines. The material showed a quantitative distribution of ergot resistance. Weak to medium-sized correlations (0.33 ? 0.47) between locations were detected among lines. The correlation between locations was even weaker in testcrosses. Weak correlations in ergot weight per spike were observed between CMS lines and their testcrosses in sets 2 and 3. In set 1, the estimated phenotypic correlation was higher (rp = 0.65). Estimates of error-corrected correlations were always higher than phenotypic correlations. No genetic difference was detected among the CMS lines for the amount of alkaloids in their sclerotia. This study shows that incompatible rye populations as well as self-fertile hybrid populations contain a substantial genetic variation for resistance to ergot that is inherited quantitatively. In both materials, mainly additive genetic variance was found. Because of a significant genotype-environment interaction, multi-environment trials are necessary to select for resistance. The results of this study nevertheless indicate good prospects to improve resistance to ergot in rye breeding in the long term

Genome-wide association studies and prediction of tan spot (Pyrenophoratritici-repentis) infection in European winter wheat via different marker platforms

Tan spot, caused by the fungus Pyrenophoratritici-repentis (Ptr), is a severe foliar disease of wheat (Triticumaestivum L.). Improving genetic resistance is a durable strategy to reduce Ptr-related losses. Here, we dissected Ptr-infection’s genetic basis in 372 European wheat varieties via single sequence repeats (SSR) in addition to 35k and 90k single nucleotide polymorphism (SNP) marker platforms. In our phenotypic data analyses, Ptr infection showed a significant genotypic variance and a significant negative correlation with plant height. Genome-wide association studies revealed a highly quantitative nature of Ptr infection and identified two quantitative trait loci (QTL), viz., QTs.ipk-7A and QTs.ipk-7B, which imparted 21.23 and 5.84% of the genotypic variance, respectively. Besides, the Rht-D1 gene showed a strong allelic influence on the resistance scores. Due to the complex genetic nature of the Ptr infection, the potential of genome-wide prediction (GP) was assessed via three different genetic models on individual and combined marker platforms. The GP results indicated that the marker density and marker platforms do not considerably impact prediction accuracy (~40–42%) and that higher-order epistatic interactions may not be highly pervasive. Our results provide a further understanding of Ptr-infection’s genetic nature, serve as a resource for marker-assisted breeding, and highlight the potential of genome-wide selection for improved Ptr resistance

Genetic variation for resistance and mycotoxin content of European maize inoculated with Fusarium graminearum and F. verticillioides

Ear rot in maize caused by Fusarium graminearum and/or F. verticillioides is a devastating disease resulting in contamination by several mycotoxins (deoxynivalnol, DON, zearalenone, ZEA, fumonisins, FUM). Significant (P=0.01) genetic variation for resistance to ear rot and mycotoxin content was found in both early and mid-late maturity groups of adapted European maize. The resistance reaction of the genotypes is highly dependent on environment, multi-environment testing is indispensable. F. verticillioides generally produces lower amount of disease compared to F. graminearum , however, the FUM contents are still substantial. High correlations between ear rot rating and DON and FUM concentrations, respectively, allow a prescreening on the basis of visual rating. For ZEA, the results still have to be verified in further experiments

Genetic control and prospects of predictive breeding for European winter wheat's Zeleny sedimentation values and Hagberg-Perten falling number

Sedimentation values and falling number in the last decades have helped maintain high baking quality despite rigorous selection for grain yield in wheat. Allelic combinations of major loci sustained the bread-making quality while improving grain yield. Glu-D1, Pinb-D1, and non-gluten proteins are associated with sedimentation values and falling number in European wheat. Zeleny sedimentation values (ZSV) and Hagberg-Perten falling number (HFN) are among the most important parameters that help determine the baking quality classes of wheat and, thus, influence the monetary benefits for growers. We used a published data set of 372 European wheat varieties evaluated in replicated field trials in multiple environments. ZSV and HFN traits hold a wide and significant genotypic variation and high broad-sense heritability. The genetic correlations revealed positive and significant associations of ZSV and HFN with each other, grain protein content (GPC) and grain hardness; however, they were all significantly negatively correlated with grain yield. Besides, GPC appeared to be the major predictor for ZSV and HFN. Our genome-wide association analyses based on high-quality SSR, SNP, and candidate gene markers revealed a strong quantitative genetic nature of ZSV and HFN by explaining their total genotypic variance as 41.49% and 38.06%, respectively. The association of known Glutenin (Glu-1) and Puroindoline (Pin-1) with ZSV provided positive analytic proof of our studies. We report novel candidate loci associated with globulins and albumins-the non-gluten monomeric proteins in wheat. In addition, predictive breeding analyses for ZSV and HFN suggest using genomic selection in the early stages of breeding programs with an average prediction accuracy of 81 and 59%, respectively

Genome-Based Identification of Heterotic Patterns in Rice

Abstract Background Hybrid rice breeding facilitates to increase grain yield and yield stability. Long-term success of hybrid breeding depends on the recognition of high-yielding complementary heterotic patterns, which is lacking in crops like rice. Result The main goal of this study was to evaluate the potential and limits to use genomics for establishing heterotic patterns in rice. For this purpose, data of a commercial hybrid rice breeding program targeted to India was analyzed, including 1,960 phenotyped hybrids from three market segments and 262 genotyped parental lines. Our cross-validation study revealed that grain yield of all potential single-crosses can be accurately predicted. Based on the full matrix of hybrid performances, high-yielding heterotic patterns were identified. These heterotic patterns increased grain yield up to 9% compared to the currently employed groups. Heterotic groups of around 14 individuals reflect a good compromise between long-term and short-term selection response. Conclusions Our findings clearly underlined the benefits of a genome-based establishment of heterotic patterns in rice as a requirement for a sustainable long-term success of hybrid rice breeding

Additional file 2: of Genome-Based Identification of Heterotic Patterns in Rice

Best linear unbiased estimations for hybrid grain yield experiments in market segments LS, MM, and SS. (XLSX 76 kb

Additional file 1: of Genome-Based Identification of Heterotic Patterns in Rice

for Genome-based identification of heterotic. Figure S1. Decay of linkage disequilibrium measured using r2 with physical map distance. Figure S2. Principal coordinate analysis of all parental lines for market segments LS, MM, and SS. Figure S3. Applied cross validation scenario exemplifying the selected fractions for market segment MM. Figure S4. Unbalanced factorial crossing designs for market segment (A) LS, (B) MM, and (C) SS. Figure S5. Venn diagram of overlapping parental lines of the hybrid evaluation trials in market segments LS, MM, and SS. Figure S6. Experimental design and distribution of checks for hybrid experiment of market segment MM at location HYD. Orange and black lines represent the size of trials and blocks, respectively. White plots were not phenotyped. Table S1. Composition of heterotic groups selected with the simulated annealing algorithm as well as the average hybrid performance between both heterotic groups (Inter) for the market segments LS, MM, and SS. Table S2. Composition of estimation and test populations for market segment LS, MM, and SS. (DOCX 1811 kb

Unlocking big data doubled the accuracy in predicting the grain yield in hybrid wheat

The potential of big data to support businesses has been demonstrated in financial services, manufacturing, and telecommunications. Here, we report on efforts to enter a new data era in plant breeding by collecting genomic and phenotypic information from 12,858 wheat genotypes representing 6575 single-cross hybrids and 6283 inbred lines that were evaluated in six experimental series for yield in field trials encompassing ~125,000 plots. Integrating data resulted in twofold higher prediction ability compared with cases in which hybrid performance was predicted across individual experimental series. Our results suggest that combining data across breeding programs is a particularly appropriate strategy to exploit the potential of big data for predictive plant breeding. This paradigm shift can contribute to increasing yield and resilience, which is needed to feed the growing world population