Resistance of Maize (Zea mays L.) Against the European Corn Borer (Ostrinia nubilalis Hb.) and its Association with Mycotoxins Produced by Fusarium spp.

Der Maiszünsler (ECB, Ostrinia nubilalis Hübner) ist einer der Hauptschädlinge im europäischen Maisanbau (Zea mays L.) und breitet sich derzeit weiter in nördlicher gelegene Anbaugebiete aus. ECB-Schäden beeinträchtigen daher zunehmend die Ertragssicherheit in der Maisproduktion. Zusätzlich besitzen die vom ECB befallenen Pflanzen oft eine erhöhte Empfindlichkeit gegenüber den von Fusariumpilzen (Fusarium spp.) verursachten Sekundärkinfektionen. Allerdings sind derzeit noch keine Informationen zu Bt-Maishybriden (Event 176, MON810) verfügbar, welche eventuell auch unter zentraleuropäischen Wachstumsbedingungen Ertragsverluste und Mykotoxinkontaminationen verringern könnten. Jedoch besteht die Gefahr, dass monogene Resistenzen vom Schadinsekt überwunden werden können. Daher kann die Verbesserung der natürlichen Widerstandskraft der Pflanze ein ökonomisches sowie ein ökologisches Konzept für den integrierten Pflanzenschutz bieten. Ziel der vorliegenden Studie war die Untersuchung alternativer Züchtungsstrategien zur Verbesserung der Resistenz von Mais gegen ECB und Fusariosen. Hierzu wurden (1) ein Selektionsexperiment im frühreifen Europäischen Flintpool initiiert und ein Peedigreezuchtprogramm zur Verbesserung der ECB-Resistenz im frühreifen Europäischen Dentpool evaluiert; (2) die Wirkung von quantitativen Resistenzen und Bt-Resistenz miteinander verglichen; (3) die Mykotoxingehalte in Genotypen mit verbesserter ECB Resistenz ermittelt und (4) der Zusammenhang zwischen wichtigen agronomischen Eigenschaften, der ECB-Resistenz und der Mykotoxinkonzentration im frühreifen europäischen Maismaterial untersucht. Ziel eines 1992 iniitierten Zuchtprogramms war die Identifizierung von Maislinien mit verbesserter Eigen- und Testkreuzungsleistung für wichtige agronomische Merkmale und ECB-Resistenzeigenschaften. Der Zuchtgang wurde mit einer spaltenden S1 Population begonnen. Die Eigenleistung der Genotypen für die ECB-Resistenz wurde in Generation S1, S3 und S5 ermittelt. Mit den Maislinien der S2, S4 und S5 Generation wurden Testkreuzungen erstellt, um deren agronomische Leistung zu bewerten. Die Selektion basierte auf der ECB-Resistenz und der Testkreuzungsleistung für Kornertrag und Frühreife. Um die Bt-Maishybriden, welche das Event 176 oder MON810 besitzen, mit ihren isogenen Partnerhybriden, sowie Sorten- und Experimentalhybriden zu vergleichen, wurde in verschiedenen Umwelten von 1998 bis 2000 Feldversuche durchgeführt. Darüber hinaus wurde 1998 ein Laborversuch mit neonaten ECB-Larven angelegt, um deren Mortaliät und den vorhandenen Antibiosegrad im Hybridmaterial bestimmen zu können. Die Resistenzmerkmale Schadensbonitur des Stengels, Anzahl geschädigter Pflanzen und Anzahl der Larven pro Pflanze wurden nur in den manuell mit ECB infestierten Parzellen erhoben. Die agronomischen Merkmale Kornertrag, Korntrockensubstanzgehalt und Wuchshöhe wurden sowohl in den mit Insektizid geschützten als auch in den manuell mit ECB infestierten Großparzellen ermittelt. Zusätzlich wurden Körnerproben aus jeder Parzelle gezogen und separat auf die folgenden Fusarientoxine hin untersucht: Typ B Trichothecene (DON, NIV), Zearalenon (ZEN), Fumonisin (FUM) und Moniliformin (MON). Alle getesteten Inzuchtlinien zeigten eine signifikante genotypische Variation für die untersuchten Resistenzmerkmale. Jedoch wurden im Verlauf des weiteren Zuchtganges viele Dent- und Flintlinien mit verbesserter ECB-Resistenz aufgrund ihrer unzureichenden agronomischen Leistungen verworfen. Zudem wurden negative Korrelationen zwischen Kornertrag und Frühreife sowie der Schadensbonitur des Stengels gefunden. Jedoch konnten aus dem Zuchtprogramm drei Dentlinien (P028, P029, P030) mit mittlerer ECB-Resistenz entwickelt werden. In allen Experimenten demonstrierten die Bt-Hybriden ihre Überlegenheit in der Kontrolle von ECB. Die nichttransgenen Hybriden zeigten eine signifikante genetische Varianz für die erhobenen Resistenzmerkmale und den Kornertrag, wobei deren Kornertragsreduktion unter manueller ECB-Infestierung zwischen 8,6% und 21,8% schwankte. Alle Resistenzmerkmale waren hoch signifikant miteinander korreliert und zeigten eine signifikante und negative Korrelation zur Kornertragsreduktion. Zudem waren die Bt-Hybriden in ihren agronomischen Merkmalen nahezu nicht von den isogenen Partnerhybriden zu unterscheiden. Hochsignifikante Umwelt- sowie Genotyp × Umwelt-Interaktionen wurden außer bei MON für alle Mykotoxine nachgewiesen. Die MON-Konzentration war in den mit ECB infestierten Parzellen ungefähr zweimal höher als in den insektizidgeschützten Parzellen. Ein ähnlicher Trend wurde ebenfalls für FUM festgestellt. Die Bt-Hybriden zeigten signifikant niedrigere MON Konzentrationen als die nichttransgenen Hybriden, sowie signifikant niedrigere DON Konzentrationen als ihre isogenen Partnerhybriden unter ECB-Infestierung. Es wurden hochsignifikante Korrelationen zwischen den ECB-Resistenzmerkmalen und der MON-Konzentration gefunden. Jedoch wurde für DON, 15-A-DON, FUM und MON eine signifikante genetische Variation gefunden, was wiederum zeigt, dass ein unterschiedliches Resistenzniveau gegen Fusarium spp. in den Elitehybriden vorhanden ist. Mit Hilfe einer Pyramidisierung von verschiedenen monogenen Bt-Resistenzquellen und der verbesserten quantitativen ECB-Resistenz wäre es prinzipiell möglich, Genotypen mit einer stabilen Resistenz zu schaffen. Um neue Resistenzquellen zu identifizieren und geeignete Zuchtprogramme zu entwickeln, sind allerdings weitergehende Untersuchungen nötig. Desweiteren kann durch eine verbesserte Fusariosenresistenz ein höherer Wirkungsgrad zur Verminderung von Mykotoxinbelastungen im Erntegut erreicht werden als dies derzeit durch ein hohes ECB-Resistenzniveau möglich ist. Da ECB- und Fusariosenresistenz weitgehend unabhängig voneinander vererbt werden, ist eine gleichzeitige züchterische Bearbeitung beider Resistenzen nötig, um die Ertragssicherheit und Qualität künftiger Sorten bei Mais weiter zu verbessern.The European corn borer (ECB, Ostrinia nubilalis Hübner) is a major pest of maize (Zea mays L.) in Europe and continues to spread to northern maize growing regions. The ECB severely affects commercial maize production by decreasing yield stability. In addition, damaged plants often show an increased susceptibility to secondary infections caused by Fusarium spp.. Information about the potential of Bt hybrids (event 176, MON810) to reduce yield losses and mycotoxin contamination under Central European growing conditions is still lacking. However, such monogenic resistances with a strong negative effect on the ECB will break down rapidly. Improving the natural host plant resistance of maize could provide an economical and ecological tool for an integrated pest management system. The overall goal of this study was to evaluate alternative breeding strategies for improving resistance of maize against ECB damage and Fusarium spp.. The objectives were to (1) initiate a selection experiment in the early maturing European flint pool and evaluate a breeding program for ECB resistance in the European dent pool, (2) compare the efficiency of host plant resistance vs. Bt resistance in maize, (3) determine Fusarium-caused mycotoxin contamination of maize genotypes with improved host plant resistance to ECB, and (4) study the association between important agronomic traits, ECB resistance traits, and mycotoxin concentration in early European maize germplasm. The goal of the Hohenheim ECB breeding program, initiated in 1992, was to select lines with improved per se and testcross performance for multiple agronomic traits and ECB resistance. In the standard breeding scheme, line development started from a segregating S1 population. Genotypes were evaluated for their line per se ECB resistance in generations S1, S3, and S5. Lines from the S2, S4, and S5 generations were testcrossed and evaluated for their agronomic performance. Selection was based on ECB resistance and TC performance for grain yield and maturity. In order to compare transgenic Bt maize hybrids carrying event 176 or MON810 with their isogenic counterparts and commercial hybrids or experimental hybrids, field trials in multiple environments were conducted in 1998 to 2000. Furthermore, a laboratory bioassay with neonate ECB larvae was performed to assess mortality and subsequently the level of Bt antibiosis present in the used hybrids of 1998. Resistance traits such as damage rating of stalks, number of damaged plants, and number of larvae per plant were assessed exclusively in manually ECB infested plots. Grain yield, grain dry matter content and plant height were determined in the insecticide protected and the ECB infested main plots. In addition, grain samples from each subplot were drawn at random and analyzed separately for Fusarium mycotoxins such as type B trichothecenes (DON, NIV), Zearalenon (ZEN), Fumonisins (FUM), and Moniliformin (MON). The inbred lines displayed a significant genotypic variance for all ECB resistance traits evaluated. However, in the further course of selection and topcross testing, most dent and flint lines, especially those displaying improved resistance to ECB larvae feeding, were discarded because of their poor agronomic performance. Negative correlations between grain yield, early maturity and the damage rating of stalks were identified. However, three dent lines (P028, P029, P030) with moderate resistance to ECB were developed. In all experiments, Bt hybrids were superior to other hybrids in the control of ECB larvae. Non-Bt hybrids displayed a significant genotypic variance for all evaluated resistance traits; grain yield reductions ranged from 8.6 to 21.8% under manual infestation of ECB. All evaluated resistance traits were highly significantly correlated with each other and showed significant negative correlations to grain yield reduction. Bt hybrids did not differ from their isogenic counterparts for most agronomic traits. Highly significant location and genotype × location interactions were identified for all mycotoxins evaluated, except MON. MON concentration doubled under manual infestation of ECB compared to insecticide protected conditions and a similar trend was found for FUM. Bt hybrids displayed significantly lower MON concentrations than non-Bt hybrids and significantly lower DON concentrations than their isogenic counterparts under ECB infestation. Highly significant correlations between ECB resistance traits and MON were found. However, a significant genotypic variance was observed for DON, 15-A-DON, FUM, and MON concentrations, suggesting variation for resistance against Fusarium spp. in current elite hybrids. By combining different sources of monogenic Bt resistance and quantitatively inherited resistances to ECB, it may be possible to develop hybrids with multiple resistance by pyramiding the underlying genes in one genotype. Therefore, further research is required to identify new sources of ECB resistance and new breeding strategies should be developed. Furthermore, there is indication that an improved resistance against Fusarium spp. possesses a greater potential for reducing mycotoxin contamination of maize kernels than a high level of ECB resistance. Since resistance to ECB and resistance to Fusarium spp. are inherited fairly independently, simultaneous improvement of both resistances seems to be necessary for improving the stability and quality of future maize hybrids

Lineage-Specific Chimerism and Outcome After Hematopoietic Stem Cell Transplantation for DOCK8 Deficiency

Bi-allelic variants in the dedicator of cytokinesis 8 (DOCK8) gene cause a combined immunodeficiency, characterized by recurrent sinopulmonary and skin infections, food allergies, eczema, eosinophilia, and elevated IgE. Long-term outcome is poor given susceptibility to infections, malignancy, and vascular complications. Allogeneic hematopoietic stem cell transplantation is currently the only curative treatment option and has shown promising outcome. The impact of mixed chimerism on long-term outcome is unclear. We reasoned that reversal of disease phenotype would depend on cell lineage-specific chimerism. DOCK8 variants were confirmed by Sanger and/or exome sequencing and immunoblot and/or intracellular flow cytometry. Donor chimerism was analyzed by XY-fluorescence in situ hybridization or quantitative short tandem repeat PCR. Outcome was assessed by laboratory tests, lymphocyte subsets, intracellular DOCK8 protein flow cytometry, T-cell proliferation analysis, and multiparameter immunoblot allergy screening. We report on nine patients, four of whom with mixed chimerism, with a median follow-up of 78~months after transplantation. Overall, we report successful transplantation with improvement of susceptibility to infections and allergies, and resolution of eczema in all patients. Immunological outcome in patients with mixed chimerism suggests a selective advantage for wild-type donor T-cells but lower donor B-cell chimerism possibly results in a tendency to hypogammaglobulinemia. No increased infectious and allergic complications were associated with mixed chimerism. Aware of the relatively small cohort size, we could not demonstrate a consistent detrimental effect of mixed chimerism on clinical outcomes. We nevertheless advocate aiming for complete donor chimerism in treating DOCK8 deficiency, but recommend reduced toxicity conditioning

The leukemogenic fusion gene MLL-AF9 alters microRNA expression pattern and inhibits monoblastic differentiation via miR-511 repression

BACKGROUND: In this study we explored the role of microRNAs (miRNAs) as mediators of leukemogenic effects of the fusion gene MLL-AF9, which results from a frequent chromosomal translocation in infant and monoblastic acute myeloid leukemia (AML). METHODS: We performed a specific and efficient knockdown of endogenous MLL-AF9 in the human monoblastic AML cell line THP1. RESULTS: The knockdown associated miRNA expression profile revealed 21 MLL-AF9 dependently expressed miRNAs. Gene ontology analyses of target genes suggested an impact of these miRNAs on downstream gene regulation via targeting of transcriptional modulators as well as involvement in many functions important for leukemia maintenance as e.g. myeloid differentiation, cell cycle and stem cell maintenance. Furthermore, we identified one of the most intensely repressed miRNAs, miR-511, to raise CCL2 expression (a chemokine ligand important for immunosurveillance), directly target cyclin D1, inhibit cell cycle progression, increase cellular migration and promote monoblastic differentiation. With these effects, miR-511 may have a therapeutic potential as a pro-differentiation agent as well as in leukemia vaccination approaches. CONCLUSIONS: Our study provides new insights into the understanding of miRNAs as functional mediators of the leukemogenic fusion gene MLL-AF9 and opens new opportunities to further investigate specific therapeutic options for AML via the miRNA level. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13046-016-0283-5) contains supplementary material, which is available to authorized users

Flow cytometric measurement of STAT5 phosphorylation in cytomegalovirus-stimulated T cells

Cytomegalovirus (CMV)-specific T cells expand with CMV reactivation and are probably prerequisite for control and protection. Given the critical role STAT5A phosphorylation (pSTAT5A) in T cell proliferation, this study presents a simple and sensitive flow cytometric-based pSTAT5A assay to quickly identify CMV-specific T cell proliferation. We determined pSTAT5A in T cells treated with CMV-specific peptide mix (pp65 + IE1 peptides) from 20 healthy adult subjects and three immunodeficient patients with CARMIL-2 mutation. After stimulation, the percentage of pSTAT5A+ T cells in CMV-seropositive (CMV+) subjects significantly increased from 3.0% ± 1.9% (unstimulated) to 11.4% ± 5.9% (stimulated) for 24 h. After 7 days of stimulation, the percentage of expanded T cells amounted to 26% ± 17.2%. Conversely, the percentage of pSTAT5A+ T cells and T cell proliferation from CMV-seronegative (CMV−) subjects hardly changed (from 3.0% ± 1.3% to 3.7% ± 1.8% and from 4.3% ± 2.1% to 5.7% ± 1.7%, respectively). We analyzed the correlation between the percentage of pSTAT5A+ T cells versus (1) CMV-IgG concentrations versus (2) the percentage of expanded T cells and versus (3) the percentage of initial CMV-specific T cells. In immunodeficient patients with CARMIL-2 mutation, CMV-specific pSTAT5A and T cell proliferation were completely deficient. In conclusion, flow cytometric-based pSTAT5A assay represents an appropriate tool to quickly identify CMV-specific T cell proliferation and helps to understand dysfunctions in controlling other pathogens. Flow cytometric-based pSTAT5A assay may be a useful test in clinical practice and merits further validation in large studies

A Minimum Dilution Scenario for Supernovae and Consequences for Extremely Metal-Poor Stars

© 2020 The Author(s) 2020 Published by Oxford University Press on behalf of the Royal Astronomical Society.To date no metal-free stars have been identified by direct observations. The most common method of constraining their properties is searching the spectra of the most metal-poor stars for the chemical elements created in the first stars and their supernova (SN). In this approach, modelled SN yields are compared to the observed abundance patterns in extremely metal-poor stars. The method typically only uses the abundance ratios, i.e. the yields are diluted to the observed level. Following the usual assumption of spherical symmetry we compute a simple lower limit of the mass an SN can mix with and find that it is consistent with all published simulations of early chemical enrichment in the interstellar medium. For three different cases, we demonstrate that this dilution limit can change the conclusions from the abundance fitting. There is a large discrepancy between the dilution found in simulations of SN explosions in minihaloes and the dilution assumed in many abundance fits. Limiting the dilution can significantly alter the likelihood of which supernovae are possible progenitors of observed CEMP-no stars. In particular, some of the faint, very low yield SNe, which have been suggested as models for the abundance pattern of SMSS0313-6708, cannot explain the measured metal abundances, as their predicted metal yields are too small by two orders of magnitude. Altogether, the new dilution model presented here emphasizes the need to better understand the mixing and dilution behaviour of aspherical SNe.Peer reviewedFinal Accepted Versio

Efficiency and maximal CP-asymmetry of scalar triplet leptogenesis

We study thermal leptogenesis induced by decays of a scalar SU(2)_L triplet. Despite the presence of gauge interactions, unexpected features of the Boltzmann equations make the efficiency close to maximal in most of the parameter space. We derive the maximal CP asymmetry in triplet decays, assuming that it is generated by heavier sources of neutrino masses: in this case successful leptogenesis needs a triplet heavier than 2.8 10^{10} GeV and does not further restrict its couplings, allowing detectable mu --> e gamma, tau --> mu gamma rates in the context of supersymmetric models. Triplet masses down to the TeV scale are viable in presence of extra sources of CP-violation.Comment: 12 pages, 6 figures. Interference term added to eq. (16d), figures recomputed (the difference is almost invisible

Leptogenesis in the minimal supersymmetric triplet seesaw model

In the supersymmetric triplet (type-II) seesaw model, in which a single SU(2)_L-triplet couples to leptons, the high-energy neutrino flavour structure can be directly determined from the low-energy neutrino data. We show that even with such a minimal triplet content, leptogenesis can be naturally accommodated thanks to the resonant interference between superpotential and soft supersymmetry breaking terms.Comment: References added, discussion expanded, to appear in PL