Melatonin seed priming improves early establishment and water stress tolerance of peanut.

Water stress is a major cause of yield loss in peanut cultivation. Melatonin seed priming has been used to enhance stress tolerance in several crops, but not in peanut. We investigated the impact of seed priming with melatonin on the growth, development, and drought tolerance of two peanut cultivars, TUFRunner™ '511', a drought tolerant cultivar, and New Mexico Valencia A, a drought sensitive cultivar. Peanut seed priming tests using variable rates of melatonin (0-200 µM), indicated that 50 µM of melatonin resulted in more uniform seed germination and improved seedling growth in both cultivars under non stress conditions. Seed priming with melatonin also promoted vegetative growth, as evidenced by higher whole-plant transpiration, net CO2 assimilation, and root water uptake under both well-watered and water stress conditions in both cultivars. Higher antioxidant activity and protective osmolyte accumulation, lower reactive oxygen species accumulation and membrane damage were observed in primed compared with non-primed plants. Seed priming with melatonin induced a growth promoting effect that was more evident under well-watered conditions for TUFRunnner™ '511', whereas for New Mexico Valencia A, major differences in physiological responses were observed under water stress conditions. New Mexico Valencia A primed plants exhibited a more sensitized stress response, with faster down-regulation of photosynthesis and transpiration compared with non-primed plants. The results demonstrate that melatonin seed priming has significant potential to improve early establishment and promote growth of peanut under optimal conditions, while also improve stress tolerance during water stress.

Cardiac Surgery Outcomes in Patients Receiving Hemodialysis Versus Peritoneal Dialysis.

Rationale & Objective: We sought to compare outcomes of patients receiving dialysis after cardiothoracic surgery on the basis of dialysis modality (intermittent hemodialysis [HD] vs peritoneal dialysis [PD]). Study Design: This was a retrospective analysis. Setting & Participants: In total, 590 patients with kidney failure receiving intermittent HD or PD undergoing coronary artery bypass graft and/or valvular cardiac surgery at Cleveland Clinic were included. Exposure: The patients received PD versus HD (intermittent or continuous). Outcomes: Our primary outcomes were in-hospital and 30-day mortality. Secondary outcomes were length of stay, days in the intensive care unit, the number of intraoperative blood transfusions, postsurgical pericardial effusion, and sternal wound infection, and a composite of the following 4 in-hospital events: death, cardiac arrest, effusion, and sternal wound infection. Analytical Approach: We used χ2, Fisher exact, Wilcoxon rank sum, and t tests, Kaplan-Meier survival, and plots for analysis. Results: Among the 590 patients undergoing cardiac surgery, 62 (11%) were receiving PD, and 528 (89%) were receiving intermittent HD. Notably, 30-day Kaplan-Meier survival was 95.7% (95% CI: 93.9-97.5) for HD and 98.2% (95% CI: 94.7-100) for PD (P = 0.30). In total, 75 patients receiving HD (14.2%) and 1 patient receiving PD (1.6%) had a composite of 4 in-hospital events (death, cardiac arrest, effusion, and sternal wound infection) (P = 0.005). Out of 62 patients receiving PD, 16 (26%) were converted to HD. Limitations: Retrospective analyses are prone to residual confounding. We lacked details about nutritional data. Intensive care unit length of stay was used as a surrogate for volume status control. Patients have been followed in a single health care system. The HD cohort outnumbered the PD cohort significantly. Conclusions: When compared with PD, HD does not appear to improve outcomes of patients with kidney failure undergoing cardiothoracic surgery. Patients receiving PD had a lower incidence of a composite outcome of 4 in-hospital events (death, cardiac arrest, pericardial effusion, and sternal wound infections).

Patients receiving peritoneal dialysis (PD) are frequently switched to hemodialysis (HD) around the time of an open-heart surgery. More times than not, this is driven by the preference of nonkidney doctors, because HD is perceived to control toxins and fluids better. PD is, however, more advantageous and can achieve similar results while being gentler. In an effort to keep patients on their home PD, we analyzed how they fared when compared with their HD counterparts. Patients maintained on PD did just as well if not better around and after their open-heart surgery. Given the expected increase in patients treated with PD, efforts should be made to maintain them on their home modality even around major surgeries.

Differences in physiological and biochemical responses to short-term flooding among the three avocado (Persea americana Mill.) races.

Avocado (P. americana Mill.) trees are classified into three botanical races, Mexican (M), Guatemalan (G), and West Indian (WI), each distinguished by their geographical centers of origin. While avocados are considered highly sensitive to flooding stress, comparative responses of the different races to short-term flooding are not known. This study assessed the differences in physiological and biochemical responses among clonal, non-grafted avocado cultivars of each race to short-term (2-3 days) flooding. In two separate experiments, each with different cultivars of each race, container-grown trees were divided into two treatments: 1) flooded and 2) non-flooded. Net CO2 assimilation (A), stomatal conductance (gs), and transpiration (Tr) were measured periodically over time beginning the day before treatments were imposed, through the flooding period, and during a recovery period (after unflooding). At the end of the experiments, concentrations of sugars in leaves, stems, and roots, and reactive oxygen species (ROS), antioxidants, and osmolytes in leaves and roots were determined. Guatemalan trees were more sensitive to short-term flooding than M or WI trees based on decreased A, gs, and Tr and survival of flooded trees. Guatemalan trees generally had less partitioning of sugars, particularly mannoheptulose, to the roots of flooded compared to non-flooded trees. Principal component analysis showed distinct clustering of flooded trees by race based on ROS and antioxidant profiles. Thus, differential partitioning of sugars and ROS and antioxidant responses to flooding among races may explain the greater flooding sensitivity of G trees compared to M and WI trees.

Genetic engineering and genome editing in plants, animals and humans: Facts and myths.

Human history is inextricably linked to the introduction of desirable heritable traits in plants and animals. Selective breeding (SB) predates our historical period and has been practiced since the advent of agriculture and farming more than ten thousand years ago. Since the 1970s, methods of direct plant and animal genome manipulation are constantly being developed. These are collectively described as "genetic engineering" (GE). Plant GE aims to improve nutritional value, insect resistance and weed control. Animal GE has focused on livestock improvement and disease control. GE applications also involve medical improvements intended to treat human disease. The scientific consensus built around marketed products of GE organisms (GEOs) is usually well established, noting significant benefits and low risks. GEOs are exhaustively scrutinized in the EU and many non-EU countries for their effects on human health and the environment, but scrutiny should be equally applied to all previously untested organisms derived directly from nature or through selective breeding. In fact, there is no evidence to suggest that natural or selectively bred plants and animals are in principle safer to humans than GEOs. Natural and selectively bred strains evolve over time via genetic mutations that can be as risky to humans and the environment as the mutations found in GEOs. Thus, previously untested plant and animal strains aimed for marketing should be proven useful or harmful to humans only upon comparative testing, regardless of their origin. Highlighting the scientific consensus declaring significant benefits and rather manageable risks provided by equitably accessed GEOs, can mitigate negative predispositions by policy makers and the public. Accordingly, we provide an overview of the underlying technologies and the scientific consensus to help resolve popular myths about the safety and usefulness of GEOs.

Acute but not chronic heart failure is associated with higher mortality among patients hospitalized with pneumonia: An analysis of a nationwide database☆.

Background: Among patients admitted for pneumonia, heart failure (HF) is associated with worse outcomes. It is unclear whether this association is due to acute HF exacerbations, complex medical management, or chronic co-morbid conditions. Methods: This is a retrospective cohort study of patients admitted between July 2010 and June 2015 at 651 US hospitals with a principal diagnosis of either pneumonia or secondary diagnosis of pneumonia with a primary diagnosis of respiratory failure or sepsis. Comorbidities were identified by ICD-9 codes and medical management by daily charge codes. Patients were categorized according to the presence and acuity of admission diagnosis of HF. In-hospital mortality was the primary outcome. Secondary outcomes included length of stay, hospital cost, ICU admission, use of mechanical ventilation, vasopressors and inotropes. Logistic regression was used to study the association of outcomes with presence and acuity of HF. Results: Of 783,702 patients who met inclusion criteria, 212,203 (27%) had a diagnosis of HF. Of these, 56,306 (26.5%) had acute while 48,188 (22.7%) had chronic HF on admission; 51% had a diagnosis of unspecified HF. In multivariable-adjusted models, having any HF was associated with increased mortality (OR 1.35 [1.33 - 1.38]) compared to those without HF; increased mortality was associated with acute HF (OR 1.19 [1.15 - 1.22]) but not chronic HF (OR 0.92 [0.89 - 0.96]). Conclusion: The worse outcomes for pneumonia patients with HF appear due to acute HF exacerbations. Adjustment for HF without accounting for chronicity could lead to biased prognostic and billing estimates.

Spectral light distribution affects photosynthesis, leaf reflective indices, antioxidant activity and growth of Vanillaplanifolia.

Vanilla planifolia is an obligate sciophyte (shade plant) with crassulacean acid metabolism (CAM) photosynthesis. Plants were grown for 12 months under black, blue, green, or red photoselective shade netting (PSN) to alter the spectral light distribution impacting the plants. Light wavelengths were measured in each treatment and plants were assessed for photosynthetic characteristics, leaf chlorophyll index (LCI), maximum quantum yield of photosystem II, leaf reflectance indices, leaf area, growth, antioxidant enzymes, lipid peroxidation, reactive oxygen species (ROS), and osmolyte content. Plants grown under red PSN had a higher quantity of red and far-red light and had greater nocturnal net CO2 assimilation (NocA), leaf area and leaf dry weight than plants in the other treatments. Plants grown under blue PSN had a higher quantity of blue light, resulting in a higher LCI and maximum quantum yield than plants in the other treatments. Plants grown under the red and blue PSN had increased leaf spectral reflectance indices compared to plants in the other treatments, which resulted in the highest levels of antioxidant scavenging enzymes, ascorbic acid (AsA), proline, and glycine betaine, and the lowest levels of H2O2. These findings demonstrate that increasing light in the red and far-red or blue portions of the spectrum by using PSN alters the photosynthetic and/or antioxidant responses of V. planifolia and increasing red and far-red light by using red PSN can also accelerate plant growth, possibly due to higher photosynthesis.

Auxin Homeostasis and Distribution of the Auxin Efflux Carrier PIN2 Require Vacuolar NHX-Type Cation/H+ Antiporter Activity.

The Arabidopsis vacuolar Na+/H+ transporters (NHXs) are important regulators of intracellular pH, Na+ and K+ homeostasis and necessary for normal plant growth, development, and stress acclimation. Arabidopsis contains four vacuolar NHX isoforms known as AtNHX1 to AtNHX4. The quadruple knockout nhx1nhx2nhx3nhx4, lacking any vacuolar NHX-type antiporter activity, displayed auxin-related phenotypes including loss of apical dominance, reduced root growth, impaired gravitropism and less sensitivity to exogenous IAA and NAA, but not to 2,4-D. In nhx1nhx2nhx3nhx4, the abundance of the auxin efflux carrier PIN2, but not PIN1, was drastically reduced at the plasma membrane and was concomitant with an increase in PIN2 labeled intracellular vesicles. Intracellular trafficking to the vacuole was also delayed in the mutant. Measurements of free IAA content and imaging of the auxin sensor DII-Venus, suggest that auxin accumulates in root tips of nhx1nhx2nhx3nhx4. Collectively, our results indicate that vacuolar NHX dependent cation/H+ antiport activity is needed for proper auxin homeostasis, likely by affecting intracellular trafficking and distribution of the PIN2 efflux carrier.

Primed acclimation: A physiological process offers a strategy for more resilient and irrigation-efficient crop production.

Optimizing plant physiological function is essential to maintaining crop yields under water scarcity and in developing more water-efficient production practices. However, the most common strategies in addressing water conservation in agricultural production have focused on water-efficient technologies aimed at managing water application or on improving crop water-use efficiency through breeding. Few management strategies explicitly consider the management or manipulation of plant physiological processes, but one which does is termed primed acclimation (PA). The PA strategy uses the physiological processes involved in priming to pre-acclimate plants to water deficits while reducing irrigation. It has been shown to evoke multi-mechanistic responses across numerous crop species. A combination of existing literature and emerging studies find that mechanisms for pre-acclimating plants to water deficit stress include changes in root:shoot partitioning, root architecture, water use, photosynthetic characteristics, osmotic adjustment and anti-oxidant production. In many cases, PA reduces agricultural water use by improving plant access to existing soil water. Implementing PA in seasonally water-limited environments can mitigate yield losses to drought. Genotypic variation in PA responses offers the potential to screen for crop varieties with the greatest potential for beneficial priming responses and to identify specific priming and acclimation mechanisms. In this review we: 1) summarize the concept of priming within the context of plant stress physiology; 2) review the development of a PA management system that utilizes priming for water conservation in agroecosystems; and 3) address the future of PA, how it should be evaluated across crop species, and its utility in managing crop stress tolerance.

Correction to: Serum magnesium, mortality and disease progression in chronic kidney disease.

Following publication of the original article [1], we have been notified that the name of one author was spelled incorrectly as Georges N. Na khoul, when the correct spelling is Georges N. Nakhoul.

Serum magnesium, mortality and disease progression in chronic kidney disease.

INTRODUCTION: Magnesium disorders are commonly encountered in chronic kidney disease (CKD) and are typically a consequence of decreased kidney function or frequently prescribed medications such as diuretics and proton pump inhibitors. While hypomagnesemia has been linked with increased mortality, the association between elevated magnesium levels and mortality is not clearly defined. Additionally, associations between magnesium disorders, type of death, and CKD progression have not been reported. Therefore, we studied the associations between magnesium levels, CKD progression, mortality, and cause specific deaths in patients with CKD. METHODS: Using the Cleveland Clinic CKD registry, we identified 10,568 patients with estimated Glomerular Filtration Rate (eGFR) between 15 and 59 ml/min/1.73 m2 in this range for a minimum of 3 months with a measured magnesium level. We categorized subjects into 3 groups based on these magnesium levels (≤ 1.7, 1.7-2.6 and > 2.6 mg/dl) and applied cox regression modeling and competing risk models to identify associations with overall and cause-specific mortality. We also evaluated the association between magnesium level and slope of eGFR using mixed models. RESULTS: During a median follow-up of 3.7 years, 4656 (44%) patients died. After adjusting for relevant covariates, a magnesium level < 1.7 mg/dl (vs. 1.7-2.6 mg/dl) was associated with higher overall mortality (HR = 1.14, 95% CI: 1.04, 1.24), and with higher sub-distribution hazards for non-cardiovascular non-malignancy mortality (HR = 1.29, 95% CI: 1.12, 1.49). Magnesium levels > 2.6 mg/dl (vs. 1.7-2.6 mg/dl) was associated with a higher risk of all-cause death only (HR = 1.23, 95% CI: 1.03, 1.48). We found similar results when evaluating magnesium as a continuous measure. There were no significant differences in the slope of eGFR across all three magnesium groups (p = 0.10). CONCLUSIONS: In patients with CKD stage 3 and 4, hypomagnesemia was associated with higher all-cause and non-cardiovascular non-malignancy mortality. Hypermagnesemia was associated with higher all-cause mortality. Neither hypo nor hypermagnesemia were associated with an increased risk of CKD progression.

Genomics-based diversity analysis of Vanilla species using a Vanilla planifolia draft genome and Genotyping-By-Sequencing.

Demand for all-natural vanilla flavor is increasing, but its botanical source, Vanilla planifolia, faces critical challenges arising from a narrow germplasm base and supply limitations. Genomics tools are the key to overcoming these limitations by enabling advanced genetics and plant breeding for new cultivars with improved yield and quality. The objective of this work was to establish the genomic resources needed to facilitate analysis of diversity among Vanilla accessions and to provide a resource to analyze other Vanilla collections. A V. planifolia draft genome was assembled and used to identify 521,732 single nucleotide polymorphism (SNP) markers using Genotyping-By-Sequencing (GBS). The draft genome had a size of 2.20 Gb representing 97% of the estimated genome size. A filtered set of 5,082 SNPs was used to genotype a living collection of 112 Vanilla accessions from 23 species including native Florida species. Principal component analysis of the genetic distances, population structure, and the maternally inherited rbcL gene identified putative hybrids, misidentified accessions, significant diversity within V. planifolia, and evidence for 12 clusters that separate accessions by species. These results validate the efficiency of genomics-based tools to characterize and identify genetic diversity in Vanilla and provide a significant tool for genomics-assisted plant breeding.

Cation Specificity of Vacuolar NHX-Type Cation/H+ Antiporters.

Cation/H+ (NHX-type) antiporters are important regulators of intracellular ion homeostasis and are critical for cell expansion and plant stress acclimation. In Arabidopsis (Arabidopsis thaliana), four distinct NHX isoforms, named AtNHX1 to AtNHX4, locate to the tonoplast. To determine the concerted roles of all tonoplast NHXs on vacuolar ion and pH homeostasis, we examined multiple knockout mutants lacking all but one of the four vacuolar isoforms and quadruple knockout plants lacking any vacuolar NHX activity. The nhx triple and quadruple knockouts displayed reduced growth phenotypes. Exposure to sodium chloride improved growth while potassium chloride was deleterious to some knockouts. Kinetic analysis of K+ and Na+ transport indicated that AtNHX1 and AtNHX2 are the main contributors to both vacuolar pH and K+ and Na+ uptake, while AtNHX3 and AtNHX4 differ in Na+/K+ selectivity. The lack of any vacuolar NHX activity resulted in no K+ uptake, highly acidic vacuoles, and reduced but not abolished vacuolar Na+ uptake. Additional K+/H+ and Na+/H+ exchange activity assays in the quadruple knockout indicated Na+ uptake that was not H+ coupled, suggesting the existence of an alternative, cation/H+-independent, Na+ conductive pathway in vacuoles. These results highlight the importance of NHX-type cation/H+ antiporters in the maintenance of cellular cation homeostasis and in growth and development.

Salt tolerance of two perennial grass Brachypodium sylvaticum accessions.

KEY MESSAGE: We studied the salt stress tolerance of two accessions isolated from different areas of the world (Norway and Tunisia) and characterized the mechanism(s) regulating salt stress in Brachypodium sylvaticum Osl1 and Ain1. Perennial grasses are widely grown in different parts of the world as an important feedstock for renewable energy. Their perennial nature that reduces management practices and use of energy and agrochemicals give these biomass crops advantages when dealing with modern agriculture challenges such as soil erosion, increase in salinized marginal lands and the runoff of nutrients. Brachypodium sylvaticum is a perennial grass that was recently suggested as a suitable model for the study of biomass plant production and renewable energy. However, its plasticity to abiotic stress is not yet clear. We studied the salt stress tolerance of two accessions isolated from different areas of the world and characterized the mechanism(s) regulating salt stress in B. sylvaticum Osl1, originated from Oslo, Norway and Ain1, originated from Ain-Durham, Tunisia. Osl1 limited sodium transport from root to shoot, maintaining a better K/Na homeostasis and preventing toxicity damage in the shoot. This was accompanied by higher expression of HKT8 and SOS1 transporters in Osl1 as compared to Ain1. In addition, Osl1 salt tolerance was accompanied by higher abundance of the vacuolar proton pump pyrophosphatase and Na+/H+ antiporters (NHXs) leading to a better vacuolar pH homeostasis, efficient compartmentation of Na+ in the root vacuoles and salt tolerance. Although preliminary, our results further support previous results highlighting the role of Na+ transport systems in plant salt tolerance. The identification of salt tolerant and sensitive B. sylvaticum accessions can provide an experimental system for the study of the mechanisms and regulatory networks associated with stress tolerance in perennials grass.

ABA Is Required for Plant Acclimation to a Combination of Salt and Heat Stress.

Abiotic stresses such as drought, heat or salinity are a major cause of yield loss worldwide. Recent studies revealed that the acclimation of plants to a combination of different environmental stresses is unique and cannot be directly deduced from studying the response of plants to each of the different stresses applied individually. Here we report on the response of Arabidopsis thaliana to a combination of salt and heat stress using transcriptome analysis, physiological measurements and mutants deficient in abscisic acid, salicylic acid, jasmonic acid or ethylene signaling. Arabidopsis plants were found to be more susceptible to a combination of salt and heat stress compared to each of the different stresses applied individually. The stress combination resulted in a higher ratio of Na+/K+ in leaves and caused the enhanced expression of 699 transcripts unique to the stress combination. Interestingly, many of the transcripts that specifically accumulated in plants in response to the salt and heat stress combination were associated with the plant hormone abscisic acid. In accordance with this finding, mutants deficient in abscisic acid metabolism and signaling were found to be more susceptible to a combination of salt and heat stress than wild type plants. Our study highlights the important role abscisic acid plays in the acclimation of plants to a combination of two different abiotic stresses.

pH Regulation by NHX-Type Antiporters Is Required for Receptor-Mediated Protein Trafficking to the Vacuole in Arabidopsis.

Protein trafficking requires proper ion and pH homeostasis of the endomembrane system. The NHX-type Na(+)/H(+) antiporters NHX5 and NHX6 localize to the Golgi, trans-Golgi network, and prevacuolar compartments and are required for growth and trafficking to the vacuole. In the nhx5 nhx6 T-DNA insertional knockouts, the precursors of the 2S albumin and 12S globulin storage proteins accumulated and were missorted to the apoplast. Immunoelectron microscopy revealed the presence of vesicle clusters containing storage protein precursors and vacuolar sorting receptors (VSRs). Isolation and identification of complexes of VSRs with unprocessed 12S globulin by 2D blue-native PAGE/SDS-PAGE indicated that the nhx5 nhx6 knockouts showed compromised receptor-cargo association. In vivo interaction studies using bimolecular fluorescence complementation between VSR2;1, aleurain, and 12S globulin suggested that nhx5 nhx6 knockouts showed a significant reduction of VSR binding to both cargoes. In vivo pH measurements indicated that the lumens of VSR compartments containing aleurain, as well as the trans-Golgi network and prevacuolar compartments, were significantly more acidic in nhx5 nhx6 knockouts. This work demonstrates the importance of NHX5 and NHX6 in maintaining endomembrane luminal pH and supports the notion that proper vacuolar trafficking and proteolytic processing of storage proteins require endomembrane pH homeostasis.