Resistant and susceptible pea lines harbour different root-rot pathogens and antagonistic fungi

Disease resistance encompasses the mechanisms that allow a plant to withstand or ward off a pathogen. The molecular responses of plants under pathogen attack and the underlying genetics have been extensively studied. However, resistance is not only a trait defined by the warfare between pathogen and host. In fact, resistance is an emergent phenotype of the interactions between the microbial community and the host. Fungal root diseases threaten pea (Pisum sativum L.) cultivation, and therefore a valuable protein source and important crop in low-input farming systems. Resistance in current pea varieties against multiple root pathogens is lacking. In order to acknowledge the rhizosphere microbiome as an integral part of the environment, 261 pea genotypes were screened for resistance on naturally infested field soil in a pot-based experiment. Thereof, eight lines with contrasting disease levels were selected and tested on four soils with different disease pressure in a follow-up pot experiment. Along root rot assessments, pea pathogens (F. solani, F. oxysporum, F. avenaceum, A. euteiches, P. ultimum and D. pinodella) and arbuscular mycorrhizal fungi were quantified in diseased roots using qPCR assays. The amount of fungal DNA detected in the roots differed among the pea genotypes and the four soils and a significant pea genotype x soil interaction was evidenced for several pathogen species. For example, the quantity of F. avenaceum in the roots mostly depends on the soil (two-way ANOVA, p < 0.01) and differs significantly between pea genotypes (p = 0.013). F. oxysporum and F. solani quantities showed significant pea genotype x soil interactions (p < 0.01 for both species). Significant correlations were found between F. avenaceum and F. solani quantity and root rot index (rs = 0.38, p < 0.01 and rs = 0.56, p < 0.01, respectively ). On the other hand, F. oxysporum quantity shows no relationship with root rot (rs = 0.007, p = 0.95). These results suggest differential roles of the microbes in the pea root rot and highlight the importance of incorporating the complexity of the soil microbiome at early stages of resistance screenings and breeding efforts. Resistance breeding against root rot will be challenged by the fact that soil microbes interact with each other and the plant and that their composition varies between different soils. Further insights into plant-microbe interactions and emerging molecular plant breeding tools will fuel future plant breeding

Neutrino Masses and Mixing in Brane-World Theories

We present a comprehensive study of five-dimensional brane-world models for neutrino physics based on flat compactifications. Particular emphasis is put on the inclusion of bulk mass terms. We derive a number of general results for such brane-world models with bulk mass terms. In particular, in the limit of small brane-bulk couplings, the electroweak eigenstates are predominantly given as a superposition of three light states with non-trivial small admixtures of bulk states. As a consequence, neutrinos can undergo standard oscillations as well as oscillation into bulk Kaluza-Klein states. We use this structure to construct a specific model based on Z_2 orbifolding and bulk Majorana masses which is compatible with all observed oscillation phenomena. The solar neutrino deficit is explained by oscillations into sterile bulk states while the atmospheric neutrino deficit is due to mu - tau oscillations with naturally maximal mixing. In addition, the model can accommodate the LSND result and a significant neutrino dark matter component. We also analyze the constraints from supernova energy loss on neutrino brane-world theories and show that our specific model is consistent with these constraints.Comment: 45 pages, Latex, 1 eps-figur

Improving disease resistance of pea - clues from plant-microbe interactions

Pea (Pisum sativum L.) is a valuable protein source for food and feed. Pea is able to significantly improve soil fertility and, hence, represents an ecologically important crop in low-input farming systems. Despite their importance, pea cultivation remains below expectations due to low and unstable yields caused by a complex of soil-borne pathogens. The goal of this project is to improve our understanding of resistance mechanisms of pea against soil-borne diseases. To achieve this goal, more than 300 pea lines were evaluated for resistance in pot-experiments and a subset of susceptible and resistant pea genotypes has been identified. In a next step, key pathogens and beneficials in the pea rhizosphere and the role of root exudates in determining the occurrence of these microbes will be investigated. The study will shed light on the complex interactions between pea genotypes and soil microbes, and promote resistance breeding programmes for legumes

Improving disease resistance of pea through selection at the plant-soil interface

Pea (Pisum sativum L.) belongs to the legume family (Fabaceae). Legumes form mutualistic symbiosis with nitrogen fixing rhizobacteria and, thereby, are able to improve soil fertility. Legume crops are important protein source for food and feed and contribute to the nitrogen demand of succeeding crops. Despite their importance, cultivation of cool-season legumes in temperate zones remains below expectations due to low and unstable yields. Soil fatigue is caused by a complex of different soil-borne pathogens and thought to be the main reason for yield losses, especially in pea. Plants have the ability to actively shape the community of root associated microbes through root exudations. Evidence is growing that there is considerable genetic variation for plant traits involved in the regulation of plant-microbe interactions, and that these genetic resources can be exploited by plant breeders. The overall goal of this project is to improve resistance of pea against soil-borne diseases. So far, more than 300 pea accessions have been screened for resistance in a standardised growth chamber pot-experiment and a subset of susceptible and tolerant pea genotypes has been identified. The results of the pot-experiment will be verified in on-farm trials with repeated pea cultivation in the recent crop rotation history or clear evidence for soil fatigue. In a next step, key pathogens and beneficials will be assessed by quantitative real-time PCR and linked to root exudate profiles of pea varieties with contrasting resistance levels. The role of root exudates in shaping the plants’ own detrimental or beneficial microbial community in the rhizosphere will be investigated using High-Performance-Thin-Layer-Chromatography. Furthermore, we will identify resistance associated quantitative trait loci (QTL) via genome-wide association study. The study will shed light on the complex interactions between pea and soil microbes and promote resistance breeding programmes for legumes

Genome-wide association study for resistance of pea against a complex of root rot pathogens

Fungal root diseases severely narrow yield in pea (Pisum sativum L.) cultivation, threatening this highly valuable protein source and important crop in low input-farming systems. Adequate resistance in current pea varieties against various root pathogens is largely lacking. The control of these pathogens is challenging, as they occur as pathogen complexes in the field, themselves embeded in entangled interactions in the rhizosphere. Plants have the ability to actively shape their rootassociated microbiome and genetic variation for rhizosphere related traits exists that can potentially be harnessed in resistance breeding. Results from a controlled pot-based resistance screening of 312 pea cultivars, advanced breeding lines and gene bank accessions on naturally infested soil will be presented. Based on different disease assessments, significant differences in resistance level between pea lines were identified. Validation of a subset of most contrasting lines in the field confirmed significant differences for diseases susceptibility. ITS amplicon sequencing of the fungal rhizosphere community showed a root community of evenly abundant fungal taxonomic units not dominated by a few taxa. This finding points at complex interactions within the fungal community. Along the microbiome sequencing approach, quantitative real-time PCR assays targeting the most important pathogen species are being implemented for the analysis of pot and field rhizosphere samples. Finally, first results of a genome-wide association study on resistance to root rot will be presented

Improving disease resistance of pea through selection at the plant-soil interface

Legumes are able to improve soil fertility via a mutualistic symbiosis with nitrogen-fixing rhizobacteria. Therefore, they represent ecologically important crops for sustainable farming systems. Besides their ecological function, grain legumes considerably contribute to the dietary protein N needs of humans (Graham and Vance 2003). Despite their importance, legume cultivation remains low due to low and unstable yields (Rubiales and Mikic 2015). Soil fatigue, also called legume yield depression syndrome, is caused by a complex of different soil-borne pathogens and thought to be the main reason for these yield losses, especially in pea (Pisum sativum) (Fuchs et al. 2014). The overall goal of this project is to improve the resistance of pea against soil-borne diseases. More than 250 pea lines (varieties, advanced breeding material and GenBank accessions) will be screened for resistance in standardised growth chamber experiments and on-farm. A screening tool for breeders will be developed in collaboration with Getreidezüchtung Peter Kunz. The role of root exudates in shaping the plants’ own detrimental or beneficial microbial community in the rhizosphere will be investigated by HPTLC in collaboration with Giessen University, Germany, and CAMAG, Switzerland. Key pathogens and beneficials will be characterised by quantitative real-time PCR and linked to root exudate profiles of pea varieties with contrasting resistance levels. In addition, we will identify resistance associated quantitative trait loci via genome-wide association study. Our study will shed light on the complex interactions between pea and soil microbes and promote resistance breeding programmes for legumes. This project is supported by the Mercator Foundation Switzerland and the Swiss Federal Office of Agriculture

M-Theory on S^1/Z_2 : New Facts from a Careful Analysis

We carefully re-examine the issues of solving the modified Bianchi identity, anomaly cancellations and flux quantization in the S^1/Z_2 orbifold of M-theory using the boundary-free "upstairs" formalism, avoiding several misconceptions present in earlier literature. While the solution for the four-form G to the modified Bianchi identity appears to depend on an arbitrary parameter b, we show that requiring G to be globally well-defined, i.e. invariant under small and large gauge and local Lorentz transformations, fixes b=1. This value also is necessary for a consistent reduction to the heterotic string in the small-radius limit. Insisting on properly defining all fields on the circle, we find that there is a previously unnoticed additional contribution to the anomaly inflow from the eleven-dimensional topological term. Anomaly cancellation then requires a quadratic relation between b and the combination lambda^6/kappa^4 of the gauge and gravitational coupling constants lambda and kappa. This contrasts with previous beliefs that anomaly cancellation would give a cubic equation for b. We observe that our solution for G automatically satisfies integer or half-integer flux quantization for the appropriate cycles. We explicitly write out the anomaly cancelling terms of the heterotic string as inherited from the M-theory approach. They differ from the usual ones by the addition of a well-defined local counterterm. We also show how five-branes enter our analysis.Comment: 32 pages, version to appear in Nucl. Phys. B, no figures, uses PHYZZ

A new model for quantum dot light emitting-absorbing devices : dedicated to the memory of Pierre Duclos

Motivated by the Jaynes-Cummings (JC) model, we consider here a quantum dot coupled simultaneously to a reservoir of photons and to two electric leads (free-fermion reservoirs). This Jaynes-Cummings-Leads (JCL) model makes possible that the fermion current through the dot creates a photon flux, which describes a light-emitting device. The same model also describes a transformation of the photon flux into a fermion current, i.e. a quantum dot light-absorbing device. The key tool to obtain these results is an abstract Landauer-Büttiker formula

Bayesian Models for Unit Discovery on a Very Low Resource Language

Developing speech technologies for low-resource languages has become a very active research field over the last decade. Among others, Bayesian models have shown some promising results on artificial examples but still lack of in situ experiments. Our work applies state-of-the-art Bayesian models to unsupervised Acoustic Unit Discovery (AUD) in a real low-resource language scenario. We also show that Bayesian models can naturally integrate information from other resourceful languages by means of informative prior leading to more consistent discovered units. Finally, discovered acoustic units are used, either as the 1-best sequence or as a lattice, to perform word segmentation. Word segmentation results show that this Bayesian approach clearly outperforms a Segmental-DTW baseline on the same corpus.Comment: Accepted to ICASSP 201

Suppression of eukaryotic initiation factor 4E prevents chemotherapy-induced alopecia

BACKGROUND: Chemotherapy-induced hair loss (alopecia) (CIA) is one of the most feared side effects of chemotherapy among cancer patients. There is currently no pharmacological approach to minimize CIA, although one strategy that has been proposed involves protecting normal cells from chemotherapy by transiently inducing cell cycle arrest. Proof-of-concept for this approach, known as cyclotherapy, has been demonstrated in cell culture settings. METHODS: The eukaryotic initiation factor (eIF) 4E is a cap binding protein that stimulates ribosome recruitment to mRNA templates during the initiation phase of translation. Suppression of eIF4E is known to induce cell cycle arrest. Using a novel inducible and reversible transgenic mouse model that enables RNAi-mediated suppression of eIF4E in vivo, we assessed the consequences of temporal eIF4E suppression on CIA. RESULTS: Our results demonstrate that transient inhibition of eIF4E protects against cyclophosphamide-induced alopecia at the organismal level. At the cellular level, this protection is associated with an accumulation of cells in G1, reduced apoptotic indices, and was phenocopied using small molecule inhibitors targeting the process of translation initiation. CONCLUSIONS: Our data provide a rationale for exploring suppression of translation initiation as an approach to prevent or minimize cyclophosphamide-induced alopecia.1U01 CA168409 - NCI NIH HHS; P01 CA 87497 - NCI NIH HHS; P30 CA008748 - NCI NIH HHS; MOP-106530 - Canadian Institutes of Health Research; P01 CA013106 - NCI NIH HH