Fluctuation-Driven Molecular Transport in an Asymmetric Membrane Channel

Channel proteins, that selectively conduct molecules across cell membranes, often exhibit an asymmetric structure. By means of a stochastic model, we argue that channel asymmetry in the presence of non-equilibrium fluctuations, fueled by the cell's metabolism as observed recently, can dramatically influence the transport through such channels by a ratchet-like mechanism. For an aquaglyceroporin that conducts water and glycerol we show that a previously determined asymmetric glycerol potential leads to enhanced inward transport of glycerol, but for unfavorably high glycerol concentrations also to enhanced outward transport that protects a cell against poisoning.Comment: REVTeX4, 4 pages, 3 figures; Accepted for publication in Phys. Rev. Let

Arthropods as vectors of esca-related pathogens: Transmission efficiency of ants and earwigs and the potential of earwig feces as inoculum source in vineyards

The spread of Grapevine trunk diseases (GTDs) such as esca concerns wine growers worldwide. Besides rain-splash and air currents, arthropods may play an additional role in the dissemination of esca-related pathogens such as Phaeomoniella chlamydospora (Pch) and Phaeoacremonium minimum (Pmm). The present study confirms that black garden ants (Lasius niger L., Formicidae: Formicinae) and European earwigs (Forficula auricularia L., Dermaptera: Forficulidae) can, under artificial conditions, efficiently transmit spores of Pch and Pmm to healthy grapevine cuttings, causing new infections. The potential of earwig feces as inoculum source in vineyards is additionally discussed. Spores of Pch and Pmm retained germination ability after earwig gut passage, and infectious feces successfully infected wounded grapevine cuttings under artificial conditions. However, molecular detection frequencies of esca-related pathogens in earwig feces collected from the field were very low. With this, the risk of earwig feces as inoculum source for esca-related pathogens is probably only marginal. However, arthropods carrying esca-related spores on their exoskeletons, such as ants and earwigs, might contribute to the overall spread of esca in vineyards. The invasion of GTDs during the phase of pruning wound susceptibility, either by arthropod vectors or by airborne spores, can efficiently be prevented by adequate pruning wound protection

Effects of canopy architecture and microclimate on grapevine health in two training systems

Semi minimal pruned hedge (SMPH) is a time and cost saving grapevine training system, which is becoming more and more popular in German viticulture. In this study we compared the canopy architecture and its effect on the microclimate of SMPH trained grapevines with those of plants trained in vertical shoot positioning (VSP). We detected a 3 % points higher humidity and a 0.9 °C lower mean temperature within the complex canopy architecture of SMPH trained vines compared to VSP. Moreover, we investigated the influence of the differing microclimate, canopy and bunch architecture, as well as berry skin characteristics of the two training systems on the incidence of the major fungal grapevine diseases Downy Mildew, Powdery Mildew and Botrytis Bunch Rot, as well as on the occurrence and damage of the invasive insect pest Drosophila suzukii. We demonstrate that SMPH trained vines can be more susceptible to Downy Mildew and Powdery Mildew than VSP trained vines. The incidence of Botrytis Bunch Rot can be higher in the latter system, even if berry skin characteristics are the same in both training systems. We trapped a higher number of D. suzukii in SMPH canopies, however no increased berry damage was observed. Based on our results we recommend a more adapted plant protection regime for SMPH trained vines due to their higher susceptibility to the major fungal diseases. Furthermore, we propose a combination of SMPH and fungal resistant grapevine cultivars, e.g. 'Reberger', to achieve a more competitive, environmentally friendly and high quality grapevine production

Pushing forward white lupin as a local source for protein and nitrogen in Central Europe

White lupin (Lupinus albus L.) is a promising leguminous crop. Europe is fully dependent on protein and nitrogen fertilizer imports. This has tremendous negative effects both in Europe and the producing countries, such as loss of terrestrial biodiversity, pollution of freshwater, increase of greenhouse gases and soil acidification. Diverse crop-rotations with a substantial amount of pulses are a proven solution. The protein composition and yield potential of white lupin suggest that it could become the ‘Soy of the North’. Currently, the seed-borne pathogen Colletotrichum lupini is substantially impeding the cultivation of white lupin in Central Europe. We developed a DNA-based diagnostic test to identify and quantify the fungal pathogen in plants and seeds. This technique will allow us to improve our understanding of the Colletotrichum lupini life cycle and, thereby, lay the basis for an advanced resistance breeding approach

Identification of Hemileia vastatrix candidate effectors reveals new ways of promoting pathogen variability through alternative splicing

info:eu-repo/semantics/publishedVersio

Genetic diversity of Colletotrichum lupini and its virulence on white and Andean lupin

Lupin cultivation worldwide is threatened by anthracnose, a destructive disease caused by the seed- and air-borne fungal pathogen Colletotrichum lupini. In this study we explored the intraspecific diversity of 39 C. lupini isolates collected from different lupin cultivating regions around the world, and representative isolates were screened for their pathogenicity and virulence on white and Andean lupin. Multi-locus phylogeny and morphological characterizations showed intraspecific diversity to be greater than previously shown, distinguishing a total of six genetic groups and ten distinct morphotypes. Highest diversity was found across South America, indicating it as the center of origin of C. lupini. The isolates that correspond to the current pandemic belong to a genetic and morphological uniform group, were globally widespread, and showed high virulence on tested white and Andean lupin accessions. Isolates belonging to the other five genetic groups were mostly found locally and showed distinct virulence patterns. Two highly virulent strains were shown to overcome resistance of advanced white lupin breeding material. This stresses the need to be careful with international seed transports in order to prevent spread of currently confined but potentially highly virulent strains. This study improves our understanding of the diversity, phylogeography and pathogenicity of a member of one of the world’s top 10 plant pathogen genera, providing valuable information for breeding programs and future disease management

Genetic mapping of anthracnose resistance in white lupin

White lupin (Lupinus albus) is a valuable grain legume with a high protein content and quality, contributing to soil fertility (Monteiro et al., 2014, Lambers et al., 2013). Its high yield potential could make it a sustainable alternative for imported soybean in Europe (Lucas et al., 2015). However, lupin anthracnose, caused by the air- and soilborne fungus Colletotrichum lupini severely limits cultivation as low levels of seed infestation can already cause total yield loss (Talhinhas et al., 2016). Host resistance is crucial for managing anthracnose but a better insight into the genetic basis is required. We developed a high-throughput phenotyping tool that identifies field-relevant anthracnose resistance under controlled conditions. For inoculation, we identified a local, highly virulent C. lupini strain. Phylogenetic analyses revealed that the strain belongs to a globally dispersed genetic group corresponding to Dubrulle et al.’s (2020) C. lupini group II. Using the developed tool we phenotyped a diverse collection of 200 white lupin accessions, revealing a strong segregation between susceptible and resistant plants, potentially holding novel sources of resistance. Genotyping-bysequencing was performed and the generated single-nucleotide polymorphic markers (SNPs) are currently being used for genetic mapping. Quantitative trait loci (QTLs) for anthracnose resistance will be presented aiding to improve and speed up white lupin breeding programs

Genome‑wide association study reveals white lupin candidate gene involved in anthracnose resistance

White lupin (Lupinus albus L.) is a re-emerging protein crop and promising alternative to soybean. Its cultivation, however, is severely threatened by anthracnose disease caused by the fungal pathogen Colletotrichum lupini. To dissect the genetic architecture for anthracnose resistance, genotyping-by-sequencing (GBS) was performed on white lupin accessions collected from the center of domestication and traditional cultivation regions. GBS resulted in 4,611 high-quality single-nucleotide polymorphisms (SNPs) for 181 accessions, which were combined with resistance data observed under controlled conditions to perform a genome-wide association study (GWAS). Obtained disease phenotypes were shown to highly correlate to overall three-year disease assessments under Swiss field conditions (r > 0.8). GWAS results identified two significant SNPs associated with anthracnose resistance on gene Lalb_Chr05_g0216161 encoding a RING zinc-finger E3 ubiquitin ligase which is potentially involved in plant immunity. Population analysis showed a remarkably fast linkage disequilibrium (LD) decay, weak population structure and grouping of commercial varieties with landraces, corresponding to the slow domestication history and scarcity of modern breeding efforts in white lupin. Together with 15 highly resistant accessions identified in the resistance assay, our findings show promise for further crop improvement. This study provides the basis for marker-assisted selection, genomic prediction and studies aimed at understanding anthracnose resistance mechanisms in white lupin and contributes to improving breeding programs worldwide

Genome prediction of PhoB regulated promoters in Sinorhizobium meliloti and twelve proteobacteria

In proteobacteria, genes whose expression is modulated in response to the external concentration of inorganic phosphate are often regulated by the PhoB protein which binds to a conserved motif (Pho box) within their promoter regions. Using a position weight matrix algorithm derived from known Pho box sequences, we identified 96 putative Pho regulon members whose promoter regions contained one or more Pho boxs in the Sinorhizobium meliloti genome. Expression of these genes was examined through assays of reporter gene fusions and through comparison with published microarray data. Of 96 genes, 31 were induced and 3 were repressed by Pi starvation in a PhoB dependent manner. Novel Pho regulon members included several genes of unknown function. Comparative analysis across 12 proteobacterial genomes revealed highly conserved Pho regulon members including genes involved in Pi metabolism (pstS, phnC and ppdK). Genes with no obvious association with Pi metabolism were predicted to be Pho regulon members in S.meliloti and multiple organisms. These included smc01605 and smc04317 which are annotated as substrate binding proteins of iron transporters and katA encoding catalase. This data suggests that the Pho regulon overlaps and interacts with several other control circuits, such as the oxidative stress response and iron homeostasis