Overwintering of Erysiphe necator and Inoculum Monitoring for Decision Aids

Grape powdery mildew (Erysiphe necator) causes economic damages to grape worldwide due to the cost of management and injury to berries. Each region where European grapevine (Vitis vinifera) is grown experiences a unique epidemic, and disease prediction models that are based on empirical correlations of weather data to disease fail to predict disease accurately in regions with differing environmental conditions. Near real-time monitoring of grape powdery mildew epidemics using spore sampling and molecular detection techniques allowed grape growers to reduce fungicides applications by ~2.5 applications compared to their standard practice. Although spore sampling allowed growers to reduce fungicide applications, it is only a short-term solution to the lack of understanding of the factors surrounding initial inoculum availability. Additional factors affecting cleistothecia development and ascospore release conditions were also examined in order to improve current modeling efforts. This involved using controlled-environment studies to monitor cleistothecia initiation and development, and quantitative PCR was used to monitor ascospore release. Several established ascospore release models were tested for prediction accuracy, and an improved ascospore release prediction model was developed. The results of this work show that a portion of cleistothecia are capable of releasing ascospores before leaf drop and continue to mature and release ascospores throughout grape dormancy and into the following growing season. The results also show that an improved understanding of inoculum availability may allow grapevine growers to reduce management costs while improving disease control

Comparative Analysis of the Rhizospheric Bacterial Communities of Flue-Cured Tobacco Affected by Granville Wilt

Ralstonia solanacearum is a yield-limiting disease in flue-cured tobacco production in the Southeast United States and other major producing countries worldwide. Studies determining the association between the rhizospheric bacterial community composition, R. solanacearum distribution in the field, and soil physicochemical properties have not been conducted. In this study, the 16S rRNA gene of 144 rhizosphere samples, collected from three different fields (A, B, and C) in North Carolina, were sequenced using Illumina MiSeq v3 chemistry to (i) compare the rhizospheric bacterial community of healthy and diseased plants inside and outside “hot-spots”; (ii) identify potential bacterial indicators for Granville wilt suppression; and (iii) examine edaphic factors associated with rhizospheric bacterial composition and disease distribution in flue-cured tobacco fields. The phylum Proteobacteria was the most abundant in all fields and sampled locations within fields. Eighteen genera, including Bacillus and Pantoea, which are known antagonists of R. solanacearum, were consistently found in the rhizosphere samples from healthy plants in only one of the fields. Organic matter, Mn, and Ca contents were descriptive of the rhizosphere community structure found in healthy samples. In conclusion, the results obtained from the present study suggest that disease outcome and distribution could be associated with variation on community composition driven by edaphic factors and the presence of an antagonist. This study provides evidence of naturally occurring antagonists that could be exploited in novel management strategies for R. solanacearum suppression in modern flue-cured production systems. [Graphic: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license

Development of a quantitative loop-mediated isothermal amplification assay for the field detection of Erysiphe necator

Plant pathogen detection systems have been useful tools to monitor inoculum presence and initiate management schedules. More recently, a loop-mediated isothermal amplification (LAMP) assay was successfully designed for field use in the grape powdery mildew pathosystem; however, false negatives or false positives were prevalent in grower-conducted assays due to the difficulty in perceiving the magnesium pyrophosphate precipitate at low DNA concentrations. A quantitative LAMP (qLAMP) assay using a fluorescence resonance energy transfer-based probe was assessed by grape growers in the Willamette Valley of Oregon. Custom impaction spore samplers were placed at a research vineyard and six commercial vineyard locations, and were tested bi-weekly by the lab and by growers. Grower-conducted qLAMP assays used a beta-version of the Smart-DART handheld LAMP reaction devices (Diagenetix, Inc., Honolulu, HI, USA), connected to Android 4.4 enabled, Bluetooth-capable Nexus 7 tablets for output. Quantification by a quantitative PCR assay was assumed correct to compare the lab and grower qLAMP assay quantification. Growers were able to conduct and interpret qLAMP results; however, the Erysiphe necator inoculum quantification was unreliable using the beta-Smart-DART devices. The qLAMP assay developed was sensitive to one spore in early testing of the assay, but decreased to >20 spores by the end of the trial. The qLAMP assay is not likely a suitable management tool for grape powdery mildew due to losses in sensitivity and decreasing costs and portability for other, more reliable molecular tools

Subgroup-specific structural variation across 1,000 medulloblastoma genomes.

Medulloblastoma, the most common malignant paediatric brain tumour, is currently treated with nonspecific cytotoxic therapies including surgery, whole-brain radiation, and aggressive chemotherapy. As medulloblastoma exhibits marked intertumoural heterogeneity, with at least four distinct molecular variants, previous attempts to identify targets for therapy have been underpowered because of small samples sizes. Here we report somatic copy number aberrations (SCNAs) in 1,087 unique medulloblastomas. SCNAs are common in medulloblastoma, and are predominantly subgroup-enriched. The most common region of focal copy number gain is a tandem duplication of SNCAIP, a gene associated with Parkinson's disease, which is exquisitely restricted to Group 4α. Recurrent translocations of PVT1, including PVT1-MYC and PVT1-NDRG1, that arise through chromothripsis are restricted to Group 3. Numerous targetable SCNAs, including recurrent events targeting TGF-β signalling in Group 3, and NF-κB signalling in Group 4, suggest future avenues for rational, targeted therapy

Subgroup-specific structural variation across 1,000 medulloblastoma genomes.

Medulloblastoma, the most common malignant paediatric brain tumour, is currently treated with nonspecific cytotoxic therapies including surgery, whole-brain radiation, and aggressive chemotherapy. As medulloblastoma exhibits marked intertumoural heterogeneity, with at least four distinct molecular variants, previous attempts to identify targets for therapy have been underpowered because of small samples sizes. Here we report somatic copy number aberrations (SCNAs) in 1,087 unique medulloblastomas. SCNAs are common in medulloblastoma, and are predominantly subgroup-enriched. The most common region of focal copy number gain is a tandem duplication of SNCAIP, a gene associated with Parkinson's disease, which is exquisitely restricted to Group 4α. Recurrent translocations of PVT1, including PVT1-MYC and PVT1-NDRG1, that arise through chromothripsis are restricted to Group 3. Numerous targetable SCNAs, including recurrent events targeting TGF-β signalling in Group 3, and NF-κB signalling in Group 4, suggest future avenues for rational, targeted therapy

Divergent clonal selection dominates medulloblastoma at recurrence

The development of targeted anti-cancer therapies through the study of cancer genomes is intended to increase survival rates and decrease treatment-related toxicity. We treated a transposon-driven, functional genomic mouse model of medulloblastoma with 'humanized' in vivo therapy (microneurosurgical tumour resection followed by multi-fractionated, image-guided radiotherapy). Genetic events in recurrent murine medulloblastoma exhibit a very poor overlap with those in matched murine diagnostic samples (<5%). Whole-genome sequencing of 33 pairs of human diagnostic and post-therapy medulloblastomas demonstrated substantial genetic divergence of the dominant clone after therapy (<12% diagnostic events were retained at recurrence). In both mice and humans, the dominant clone at recurrence arose through clonal selection of a pre-existing minor clone present at diagnosis. Targeted therapy is unlikely to be effective in the absence of the target, therefore our results offer a simple, proximal, and remediable explanation for the failure of prior clinical trials of targeted therapy