Identification of a locus conferring dominant susceptibility to Pyrenophora tritici-repentis in barley

The fungus Pyrenophora tritici-repentis (Ptr) causes tan spot, a destructive foliar disease of wheat worldwide. The pathogen produces several necrotrophic effectors, which induce necrosis or chlorosis on susceptible wheat lines. Multiple races of Ptr have been identified, based on their ability to produce one or more of these effectors. Ptr has a wide host range of cereal and non-cereal grasses, but is known to cause damage only on wheat. Previously, we showed that Ptr can interact specifically with cultivated barley (Hordeum vulgare ssp. vulgare), and that the necrotrophic effector Ptr ToxB induces mild chlorosis in a highly selective manner when infiltrated into certain barley genotypes. In the present study, a barley doubled-haploid (DH) population was evaluated for reaction to Ptr race 5, a Ptr ToxB-producer. Then a comprehensive genetic map composed of 381 single nucleotide polymorphism (SNP) markers was used to map the locus conditioning this chlorosis. The F1 seedlings, and 92 DH lines derived from a cross between the resistant Japanese malting barley cultivar Haruna Nijo and the susceptible wild barley (H. vulgare ssp. spontaneum) OUH602 were inoculated with a conidial suspension of Ptr race 5 isolate at the two-leaf stage. The seedlings were monitored daily for symptoms and assessed for chlorosis development on the second leaf, 6 days after inoculation. All tested F1 seedlings exhibited chlorosis symptoms similar to the susceptible parent, and the DH lines segregated 1:1 for susceptible:resistant phenotypes, indicating the involvement of a single locus. Marker-trait linkage analysis based on interval mapping identified a single locus on the distal region of the short arm of chromosome 2H. We designate this locus Susceptibility to P. tritici-repentis1 (Spr1). The region encompassing this locus has 99 high confidence gene models, including membrane receptor-like kinases (RLKs), intracellular nucleotide-binding, leucine-rich repeat receptors (NLRs), and ankyrin-repeat proteins (ANKs). This shows the involvement of a dominant locus conferring susceptibility to Ptr in barley. Further work using high-resolution mapping and transgenic complementation will be required to identify the underlying gene

Field Crops Research

Downy brome (Bromus tectorum L.) is a problematic weed for the conventional fallow/winter wheat (F/W) production system in the low precipitation-region (\u3c 350mm yr−1) of the Pacific Northwest. A 4-yr field experiment was conducted to determine if incorporating spring barley (B, Hordeum vulgare L.) or spring carinata (C, Brassica carinata A. Braun) into 3-yr crop rotations with W would benefit weed management. The experimental design was a split-plot with four replications where each phase was present every year for the following rotations: 1) F/W, 2) F/W/B, and 3) F/W/C. Reduced tillage, consisting of a single undercutting operation with a wide-blade sweep, and herbicides were used to control weeds during the fallow period. The seeded plots were subdivided in three different weed management areas: a weed-free area where weeds were pulled by hand, a weedy area with no weed control and a general area where weeds were chemically controlled. Weed density and cover per species and W yield were evaluated in each rotation. Grass cover and density after one and two complete cropping cycles were significantly higher in F/W than in F/W/B and F/W/C. Reduction in density and cover of total weeds was found after two cycles. However, differences in community biodiversity were only found between F/W, and F/W/B or F/W/C in 2017. Winter wheat plots of F/W had more downy brome than F/ W/B or F/W/C indicating the greater capacity of the latter to control this weed. In 2018, the 3-yr rotation with barley had greater winter wheat grain yield compared with F/W when weeds were not present though weeds were more competitive in F/W/B. Intensifying the F/W cropping system into a 3-yr crop rotation of W followed by spring barley or spring carinata may reduce weed infestations of winter annual grasses that are difficult to control in W and the most competitive due to larger similarities in their life cycle with this crop

Characteristics of Subjects Who Avoid Activities and Participation Due to a Fear of Falling in Parkinson’s Disease

Background and Purpose: The purpose of this study is to examine and identify key characteristics of and differences between people with Parkinson’s Disease (PD) who exhibit moderate/high fear of falling avoidance behaviors and those that exhibit low fear of falling avoidance behaviors. Subjects: A total of 24 subjects (5 females, 19 males; mean age= 72.2, SD=9.1) participated in this study. Methods: A cross-sectional design was used to identify descriptive characteristics of subjects with PD associated with moderate/high levels of fear avoidance behavior (MHA) or low levels of fear avoidance (LA) as measured by the Fear of Falling Avoidance-Behavior Questionnaire (FFABQ). Then six profiles were used to test for differences between the MHA and LA groups: 1) demographic profile including age, socioeconomic status, and education; 2) a PD profile including the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) and its subscales, the Hoehn and Yahr Scale, the Parkinson’s Disease Questionnaire (PDQ-39) and its subscales; 3) a fall profile, including number of falls during the last month, falls in the last year, and number of falls resulting in injury; 4) a balance profile, including the Berg Balance Scale (BBS) and the Activities Specific Balance Scale (ABC); 5) a strength and conditioning profile, including the 2 minute step test (2MST), 30 second Sit to Stand Test (30STS), Timed UP and Go Test (TUGT), and the activPAL physical activity monitor; 6) and a psychological profile including the Zung Anxiety Scale (ZAS), Beck Depression Inventory (BDI), Falls Efficacy Scale (FES), Catastrophizing About Falls Scale (CAFS), and Consequences of Falling Questionnaire (CoFQ). Results: A significant difference was found between the LA and MHA groups in the following measures: Age, MDS-UPDRS, MDS-UPDRS ADL subscore, PDQ-39 mobility subscore, ABC, BBS, CAFS, and CoFQ. Discussion/Conclusion: Results of this study will assist clinicians to identify possible risk factors for high avoidance behaviors in the PD population. Further research is suggested to determine if modifiable factors can be improved and subsequently decrease avoidance behaviors in this population.

The pangenome of the wheat pathogen <i>Pyrenophora tritici-repentis</i> reveals novel transposons associated with necrotrophic effectors <i>ToxA</i> and <i>ToxB</i>

BACKGROUND: In fungal plant pathogens, genome rearrangements followed by selection pressure for adaptive traits have facilitated the co-evolutionary arms race between hosts and their pathogens. Pyrenophora tritici-repentis (Ptr) has emerged recently as a foliar pathogen of wheat worldwide and its populations consist of isolates that vary in their ability to produce combinations of different necrotrophic effectors. These effectors play vital roles in disease development. Here, we sequenced the genomes of a global collection (40 isolates) of Ptr to gain insights into its gene content and genome rearrangements. RESULTS: A comparative genome analysis revealed an open pangenome, with an abundance of accessory genes (~ 57%) reflecting Ptr’s adaptability. A clear distinction between pathogenic and non-pathogenic genomes was observed in size, gene content, and phylogenetic relatedness. Chromosomal rearrangements and structural organization, specifically around effector coding genes, were detailed using long-read assemblies (PacBio RS II) generated in this work in addition to previously assembled genomes. We also discovered the involvement of large mobile elements associated with Ptr’s effectors: ToxA, the gene encoding for the necrosis effector, was found as a single copy within a 143-kb ‘Starship’ transposon (dubbed ‘Horizon’) with a clearly defined target site and target site duplications. ‘Horizon’ was located on different chromosomes in different isolates, indicating mobility, and the previously described ToxhAT transposon (responsible for horizontal transfer of ToxA) was nested within this newly identified Starship. Additionally, ToxB, the gene encoding the chlorosis effector, was clustered as three copies on a 294-kb element, which is likely a different putative ‘Starship’ (dubbed ‘Icarus’) in a ToxB-producing isolate. ToxB and its putative transposon were missing from the ToxB non-coding reference isolate, but the homolog toxb and ‘Icarus’ were both present in a different non-coding isolate. This suggests that ToxB may have been mobile at some point during the evolution of the Ptr genome which is contradictory to the current assumption of ToxB vertical inheritance. Finally, the genome architecture of Ptr was defined as ‘one-compartment’ based on calculated gene distances and evolutionary rates. CONCLUSIONS: These findings together reflect on the highly plastic nature of the Ptr genome which has likely helped to drive its worldwide adaptation and has illuminated the involvement of giant transposons in facilitating the evolution of virulence in Ptr. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12915-022-01433-w

Resistance and Tolerance of Landrace Wheat in Fields Infested with Pratylenchus neglectus and P. thornei

Pratylenchus neglectus and P. thornei reduce wheat yields in the Pacific Northwest USA. Resistant landrace cultivars have been identified using controlled environments. Field resistance and tolerance characteristics were compared over three years and two locations for four spring wheat cultivars; the susceptible cultivars Alpowa and Louise, and the resistant landraces AUS28451 and Persia 20. Proportions and densities of P. neglectus and P. thornei differed across seasons and locations. Resistance was evaluated by comparing pre-plant and post-harvest densities of nematodes in soil. Tolerance was evaluated by comparing grain yield and grain quality in plots treated or untreated by the nematicide aldicarb. Alpowa was susceptible and intolerant, Louise was susceptible and moderately tolerant, AUS28451 was resistant and intolerant, and Persia 20 was moderately susceptible and moderately intolerant. The species dominance shifted from P. neglectus to P. thornei in one field over a period of three years in apparent response to cultivars and crops planted. Estimates of economic loss caused by Pratylenchus spp. ranged from $8 to$20/ha. Economic benefits appear to be achievable by developing a spring wheat genotype with tolerance plus resistance, such as with a cross between AUS28451 and Louise

Embedding the value of coastal ecosystem services into climate change adaptation planning

Coastal habitats, such as salt marshes and dune systems, can protect communities from hazards by reducing coastline exposure. However, these critical habitats and their diverse ecosystem services are threatened by coastal development and the impacts from a changing climate. Ever increasing pressure on coastal habitats calls for coastal climate adaptation efforts that mitigate or adapt to these pressures in ways that maintain the integrity of coastal landscapes. An important challenge for decisionmakers is determining the best mitigation and adaptation strategies that not only protect human lives and property, but also safeguard the ability of coastal habitats to provide a broad suite of benefits. Here, we present a potential pathway for local-scale climate change adaptation planning through the identification and mapping of natural habitats that provide the greatest benefits to coastal communities. The methodology coupled a coastal vulnerability model with a climate adaptation policy assessment in an effort to identify priority locations for nature-based solutions that reduce vulnerability of critical assets using feasible land-use policy methods. Our results demonstrate the critical role of natural habitats in providing the ecosystem service of coastal protection in California. We found that specific dune habitats play a key role in reducing erosion and inundation of the coastline and that several wetland areas help to absorb energy from storms and provide a protective service for the coast of Marin county, California, USA. Climate change and adaptation planning are globally relevant issues in which the scalability and transferability of solutions must be considered. This work outlines an iterative approach for climate adaptation planning at a local-scale, with opportunity to consider the scalability of an iterative science-policy engagement approach to regional, national, and international levels

Relationship of glycated haemoglobin and reported hypoglycaemia to cardiovascular outcomes in patients with type 2 diabetes and recent acute coronary syndrome events: The EXAMINE trial.

AIMS: To investigate relationships between glycated haemoglobin (HbA1c) and reported hypoglycaemia and risk of major adverse cardiovascular events (MACE). METHODS: The EXAMINE trial randomized 5380 patients with type 2 diabetes (T2DM) and a recent acute coronary syndrome (ACS) event, in 49 countries, to double-blind treatment with alogliptin or placebo in addition to standard of care. We used Cox proportional hazards models to analyse relationships among MACE, HbA1c levels and hypoglycaemic events. RESULTS: Patients randomized to alogliptin achieved lower HbA1c levels than the placebo group in all baseline HbA1c categories without differences in hypoglycaemia rates. No systematic change was found in MACE rates according to baseline HbA1c (Pinteraction  = 0.971) or HbA1c category at 1 month. Patients in the combined treatment groups (n = 5380) who experienced serious hypoglycaemia (n = 34) had higher MACE rates than those who did not (35.3% vs 11.4%, adjusted hazard ratio [HR] 2.42, 95% confidence interval [CI] 1.27-4.60; P = .007), although the association was less strong when analysing only events after the hypoglycaemic event (adjusted HR 1.60, 95% CI 0.80, 3.20). CONCLUSIONS: There were no relationships between baseline HbA1c levels or HbA1c levels after 1 month of treatment and the risk of MACE. Alogliptin improved glycaemic control without increasing hypoglycaemia. Reported events of hypoglycaemia and serious hypoglycaemia were associated with MACE. These data underscore the safety of alogliptin in improving glycaemic control in T2DM post-ACS. Further study of hypoglycaemia as an independent risk factor for MACE in patients with T2DM and coronary disease is needed

Literature and Environment, the Long View: Thoughts from the Founders of ASLE

The Association for the Study of Literature and Environment (ASLE) is the primary professional organization of scholars, teachers, and writers who study the relationships among literature, culture, and the physical environment. At a recent roundtable discussion at the Western American Literature Association's Annual Conference, "flash papers" from ASLE's founders offered a fascinating array of view points reflecting on ASLE's twenty year history. Papers look at wilderness, post naturalism, science fiction, pedagogy, publishing and climate change. It is our hope that the set of papers collected here will commemorate a historical moment and spark a continuing conversation on the future of the organization