The underground world of plant disease: Rhizosphere dysbiosis reduces above-ground plant resistance to bacterial leaf spot and alters plant transcriptome.

Just as the human gut microbiome is colonized by a variety of microbes, so too is the rhizosphere of plants. An imbalance in this microbial community, known as dysbiosis, can have a negative impact on plant health. This study sought to explore the effect of rhizosphere dysbiosis on the health of tomato plants (Solanum lycopersicum L.), using them and the foliar bacterial spot pathogen Xanthomonas perforans as model organisms. The rhizospheres of 3-week-old tomato plants were treated with either streptomycin or water as a control, and then spray-inoculated with X. perforans after 24 h. Half of the plants that were treated with both streptomycin and X. perforans received soil microbiome transplants from uninfected plant donors 48 h after the streptomycin was applied. The plants treated with streptomycin showed a 26% increase in disease severity compared to those that did not receive the antibiotic. However, the plants that received the soil microbiome transplant exhibited an intermediate level of disease severity. The antibiotic-treated plants demonstrated a reduced abundance of rhizobacterial taxa such as Cyanobacteria from the genus Cylindrospermum. They also showed a down-regulation of genes related to plant primary and secondary metabolism, and an up-regulation of plant defence genes associated with induced systemic resistance. This study highlights the vital role that beneficial rhizosphere microbes play in disease resistance, even against foliar pathogens.

Ki67 Index Correlates with Tumoral Volumetry and 5-ALA Residual Fluorescence in Glioblastoma.

BACKGROUND: Malignant gliomas are the most prevalent primary malignant cerebral tumors. Preoperative imaging plays an important role, and the prognosis is closely related to surgical resection and histomolecular aspects. Our goal was to correlate Ki67 indexes with tumoral volumetry in semiautomatic segmentation on preoperative magnetic resonance images and residual fluorescence in a 5-ALA-assisted resection cohort. METHODS: We included 86 IDH-wildtype glioblastoma patients with complete preoperative imaging submitted to 5-ALA assisted resections. Clinical, surgical, and histomolecular findings were also obtained. Preoperative magnetic resonance studies were preprocessed and segmented semiautomatically on Visualization and Analysis for whole tumor (WT) on 3D FLAIR, enhancing tumor (ET), and necrotic core on 3D postgadolinium T1. We performed a linear regression analysis for Ki67 and a multivariate analysis for surgical outcomes. RESULTS: Higher Ki-67 indexes correlated positively with higher WT (P = 0.048) and ET (P = 0.002). Lower Ki67 correlated with 5-ALA free margins (P = 0.045). WT and ET volumes correlated with the extent of resection (EOR; P = 0.002 and 0.002, respectively). Eloquence did not impact EOR (P = 0.14). CONCLUSIONS: There is a correlation between Ki67, the metabolically active tumoral volumes (WT and ET), and 5-ALA residual fluorescence. Methodological inconsistencies are probably responsible for contradictory literature findings, and further prospective studies are needed to validate and reproduce these findings.

Gradients in embolism resistance within stems driven by secondary growth in herbs.

The stems of some herbaceous species can undergo basal secondary growth, leading to a continuum in the degree of woodiness along the stem. Whether the formation of secondary growth in the stem base results in differences in embolism resistance between the base and the upper portions of stems is unknown. We assessed the embolism resistance of leaves and the basal and upper portions of stems simultaneously within the same individuals of two divergent herbaceous species that undergo secondary growth in the mature stem bases. The species were Solanum lycopersicum (tomato) and Senecio minimus (fireweed). Basal stem in mature plants of both species displayed advanced secondary growth and greater resistance to embolism than the upper stem. This also resulted in significant vulnerability segmentation between the basal stem and the leaves in both species. Greater embolism resistance in the woodier stem base was found alongside decreases in the pith-to-xylem ratio, increases in the proportion of secondary xylem, and increases in lignin content. We show that there can be considerable variation in embolism resistance across the stem in herbs and that this variation is linked to the degree of secondary growth present. A gradient in embolism resistance across the stem in herbaceous plants could be an adaptation to ensure reproduction or basal resprouting during episodes of drought late in the lifecycle.

Differential content of leaf and fruit pigment in tomatoes culminate in a complex metabolic reprogramming without growth impacts.

Although significant efforts to produce carotenoid-enriched foods either by biotechnology or traditional breeding strategies have been carried out, our understanding of how changes in the carotenoid biosynthesis might affect overall plant performance remains limited. Here, we investigate how the metabolic machinery of well characterized tomato carotenoid mutant plants [namely crimson (old gold-og), Delta carotene (Del) and tangerine (t)] adjusts itself to varying carotenoid biosynthesis and whether these adjustments are supported by a reprogramming of photosynthetic and central metabolism in the source organs (leaves). We observed that mutations og, Del and t did not greatly affect vegetative growth, leaf anatomy and gas exchange parameters. However, an exquisite metabolic reprogramming was recorded on the leaves, with an increase in levels of amino acids and reduction of organic acids. Taken together, our results show that despite minor impacts on growth and gas exchange, carbon flux is extensively affected, leading to adjustments in tomato leaves metabolism to support changes in carotenoid biosynthesis on fruits (sinks). We discuss these data in the context of our current understanding of metabolic adjustments and carotenoid biosynthesis as well as regarding to improving human nutrition.

Carbon gain is coordinated with enhanced stomatal conductance and hydraulic architecture in coffee plants acclimated to elevated [CO2]: The interplay with irradiance supply.

We recently demonstrated that, under elevated [CO2] (eCa), coffee (Coffea arabica L.) plants grown at high light (HL), but not at low light (LL), display higher stomatal conductance (gs) than at ambient [CO2] (aCa). We then hypothesized that the enhanced gs at eCa/HL, if sustained at the long-term, would lead to adjustments in hydraulic architecture. To test this hypothesis, potted plants of coffee were grown in open-top chambers for 12 months under HL or LL (ca. 9 or 1 mol photons m-2 day-1, respectively); these light treatments were combined with two [CO2] levels (ca. 437 or 705 µmol mol-1, respectively). Under eCa/HL, increased gs was closely accompanied by increases in branch and leaf hydraulic conductances, suggesting a coordinated response between liquid- and vapor-phase water flows throughout the plant. Still under HL, eCa also resulted in increased Huber value (sapwood area-to-total leaf area), sapwood area-to-stem diameter, and root mass-to-total leaf area, thus further improving the water supply to the leaves. Our results demonstrate that Ca is a central player in coffee physiology increasing carbon gain through a close association between stomatal function and an improved hydraulic architecture under HL conditions.

Abscisic acid acts essentially on stomata, not on the xylem, to improve drought resistance in tomato.

Drought resistance is essential for plant production under water-limiting environments. Abscisic acid (ABA) plays a critical role in stomata but its impact on hydraulic function beyond the stomata is far less studied. We selected genotypes differing in their ability to accumulate ABA to investigate its role in drought-induced dysfunction. All genotypes exhibited similar leaf and stem embolism resistance regardless of differences in ABA levels. Their leaf hydraulic resistance was also similar. Differences were only observed between the two extreme genotypes: sitiens (sit; a strong ABA-deficient mutant) and sp12 (a transgenic line that constitutively overaccumulates ABA), where the water potential inducing 50% embolism was 0.25 MPa lower in sp12 than in sit. Maximum stomatal and minimum leaf conductances were considerably lower in plants with higher ABA (wild type [WT] and sp12) than in ABA-deficient mutants. Variations in gas exchange across genotypes were associated with ABA levels and differences in stomatal density and size. The lower water loss in plants with higher ABA meant that lethal water potentials associated with embolism occurred later during drought in sp12 plants, followed by WT, and then by the ABA-deficient mutants. Therefore, the primary pathway by which ABA enhances drought resistance is via declines in water loss, which delays dehydration and hydraulic dysfunction.

Anthocyanins and reactive oxygen species: a team of rivals regulating plant development?

Anthocyanins are a family of water-soluble vacuolar pigments present in almost all flowering plants. The chemistry, biosynthesis and functions of these flavonoids have been intensively studied, in part due to their benefit for human health. Given that they are efficient antioxidants, intense research has been devoted to studying their possible roles against damage caused by reactive oxygen species (ROS). However, the redox homeostasis established between antioxidants and ROS is important for plant growth and development. On the one hand, high levels of ROS can damage DNA, proteins, and lipids, on the other, they are also required for cell signaling, plant development and stress responses. Thus, a balance is needed in which antioxidants can remove excessive ROS, while not precluding ROS from triggering important cellular signaling cascades. In this article, we discuss how anthocyanins and ROS interact and how a deeper understanding of the balance between them could help improve plant productivity, nutritional value, and resistance to stress, while simultaneously maintaining proper cellular function and plant growth.

Growth and Leaf Gas Exchange Upregulation by Elevated [CO2] Is Light Dependent in Coffee Plants.

Coffee (Coffea arabica L.) plants have been assorted as highly suitable to growth at elevated [CO2] (eCa), although such suitability is hypothesized to decrease under severe shade. We herein examined how the combination of eCa and contrasting irradiance affects growth and photosynthetic performance. Coffee plants were grown in open-top chambers under relatively high light (HL) or low light (LL) (9 or 1 mol photons m-2 day-1, respectively), and aCa or eCa (437 or 705 µmol mol-1, respectively). Most traits were affected by light and CO2, and by their interaction. Relative to aCa, our main findings were (i) a greater stomatal conductance (gs) (only at HL) with decreased diffusive limitations to photosynthesis, (ii) greater gs during HL-to-LL transitions, whereas gs was unresponsive to the LL-to-HL transitions irrespective of [CO2], (iii) greater leaf nitrogen pools (only at HL) and higher photosynthetic nitrogen-use efficiency irrespective of light, (iv) lack of photosynthetic acclimation, and (v) greater biomass partitioning to roots and earlier branching. In summary, eCa improved plant growth and photosynthetic performance. Our novel and timely findings suggest that coffee plants are highly suited for a changing climate characterized by a progressive elevation of [CO2], especially if the light is nonlimiting.

The Use of Synthetic Microbial Communities to Improve Plant Health.

Despite the numerous benefits plants receive from probiotics, maintaining consistent results across applications is still a challenge. Cultivation-independent methods associated with reduced sequencing costs have considerably improved the overall understanding of microbial ecology in the plant environment. As a result, now, it is possible to engineer a consortium of microbes aiming for improved plant health. Such synthetic microbial communities (SynComs) contain carefully chosen microbial species to produce the desired microbiome function. Microbial biofilm formation, production of secondary metabolites, and ability to induce plant resistance are some of the microbial traits to consider when designing SynComs. Plant-associated microbial communities are not assembled randomly. Ecological theories suggest that these communities have a defined phylogenetic organization structured by general community assembly rules. Using machine learning, we can study these rules and target microbial functions that generate desired plant phenotypes. Well-structured assemblages are more likely to lead to a stable SynCom that thrives under environmental stressors as compared with the classical selection of single microbial activities or taxonomy. However, ensuring microbial colonization and long-term plant phenotype stability is still one of the challenges to overcome with SynComs, as the synthetic community may change over time with microbial horizontal gene transfer and retained mutations. Here, we explored the advances made in SynCom research regarding plant health, focusing on bacteria, as they are the most dominant microbial form compared with other members of the microbiome and the most commonly found in SynCom studies.

Characterization of biophysical contexts leading to severe wildfires in Portugal and their environmental controls.

Characterizing the fire regime in regions prone to extreme wildfire behavior is essential for providing comprehensive insights on potential ecosystem response to fire disturbance in the context of global change. We aimed to disentangle the linkage between contemporary damage-related attributes of wildfires as shaped by the environmental controls of fire behavior across mainland Portugal. We selected large wildfires (≥100 ha, n = 292) that occurred during the 2015-2018 period, covering the full spectrum of large fire-size variation. Ward's hierarchical clustering on principal components was used to identify homogeneous wildfire contexts at landscape scale on the basis of fire size, proportion of high fire severity, and fire severity variability, and their bottom-up (pre-fire fuel type fraction, topography) and top-down (fire weather) controls. Piecewise Structural Equation Modeling was used to disentangle the direct and indirect relationships between fire characteristics and fire behavior drivers. Cluster analysis evidenced severe and large wildfires in the central region of Portugal displaying consistent fire severity patterns. Thus, we found a positive relationship between fire size and proportion of high fire severity, which was mediated by distinct fire behavior drivers involving direct and indirect pathways. A high fraction of conifer forest within wildfire perimeters and extreme fire weather were primarily responsible for those interactions. In the context of global change, our results suggest that pre-fire fuel management should be targeted at expanding the fire weather settings in which fire control is feasible and promote less flammable and more resilient forest types.

Promoter replacement of ANT1 induces anthocyanin accumulation and triggers the shade avoidance response through developmental, physiological and metabolic reprogramming in tomato.

The accumulation of anthocyanins is a well-known response to abiotic stresses in many plant species. However, the effects of anthocyanin accumulation on light absorbance and photosynthesis are unknown . Here, we addressed this question using a promoter replacement line of tomato constitutively expressing a MYB transcription factor (ANTHOCYANIN1, ANT1) that leads to anthocyanin accumulation. ANT1-overexpressing plants displayed traits associated with shade avoidance response: thinner leaves, lower seed germination rate, suppressed side branching, increased chlorophyll concentration, and lower photosynthesis rates than the wild type. Anthocyanin-rich leaves exhibited higher absorbance of light in the blue and red ends of the spectrum, while higher anthocyanin content in leaves provided photoprotection to high irradiance. Analyses of gene expression and primary metabolites content showed that anthocyanin accumulation produces a reconfiguration of transcriptional and metabolic networks that is consistent with, but not identical to those described for the shade avoidance response. Our results provide novel insights about how anthocyanins accumulation affects the trade-off between photoprotection and growth.

Elevated carbon assimilation and metabolic reprogramming in tomato high pigment mutants support the increased production of pigments.

KEY MESSAGE: High pigment mutants in tomato (Solanum lycopersicum L.), a loss of function in the control of photomorphogenesis, with greater pigment production, show altered growth, greater photosynthesis, and a metabolic reprogramming. High pigment mutations cause plants to be extremely responsive to light and produce excessive pigmentation as well as fruits with high levels of health-beneficial nutrients. However, the association of these traits with changes in the physiology and metabolism of leaves remains poorly understood. Here, we performed a detailed morphophysiological and metabolic characterization of high pigment 1 (hp1) and high pigment 2 (hp2) mutants in tomato (Solanum lycopersicum L. 'Micro-Tom') plants under different sunlight conditions (natural light, 50% shading, and 80% shading). These mutants occur in the DDB1 (hp1) and DET1 (hp2) genes, which are related to the regulation of photomorphogenesis and chloroplast development. Our results demonstrate that these mutations delay plant growth and height, by affecting physiological and metabolic parameters at all stages of plant development. Although the mutants were characterized by higher net CO2 assimilation, lower stomatal limitation, and higher carboxylation rates, with anatomical changes that favour photosynthesis, we found that carbohydrate levels did not increase, indicating a change in the energy flow. Shading minimized the differences between mutants and the wild type or fully reversed them in the phenotype at the metabolic level. Our results indicate that the high levels of pigments in hp1 and hp2 mutants represent an additional energy cost for these plants and that extensive physiological and metabolic reprogramming occurs to support increased pigment biosynthesis.

Classifying Cyber-Risky Clinical Notes by Employing Natural Language Processing.

Clinical notes, which can be embedded into electronic medical records, document patient care delivery and summarize interactions between healthcare providers and patients. These clinical notes directly inform patient care and can also indirectly inform research and quality/safety metrics, among other indirect metrics. Recently, some states within the United States of America require patients to have open access to their clinical notes to improve the exchange of patient information for patient care. Thus, developing methods to assess the cyber risks of clinical notes before sharing and exchanging data is critical. While existing natural language processing techniques are geared to de-identify clinical notes, to the best of our knowledge, few have focused on classifying sensitive-information risk, which is a fundamental step toward developing effective, widespread protection of patient health information. To bridge this gap, this research investigates methods for identifying security/privacy risks within clinical notes. The classification either can be used upstream to identify areas within notes that likely contain sensitive information or downstream to improve the identification of clinical notes that have not been entirely de-identified. We develop several models using unigram and word2vec features with different classifiers to categorize sentence risk. Experiments on i2b2 de-identification dataset show that the SVM classifier using word2vec features obtained a maximum F1-score of 0.792. Future research involves articulation and differentiation of risk in terms of different global regulatory requirements.

Exploring leaf hydraulic traits to predict drought tolerance of Eucalyptus clones.

Ongoing changes in climate, and the consequent mortality of natural and cultivated forests across the globe, highlight the urgent need to understand the plant traits associated with greater tolerance to drought. Here, we aimed at assessing key foliar traits, with a focus on the hydraulic component, that could confer a differential ability to tolerate drought in three commercial hybrids of the most important Eucalyptus species utilized in tropical silviculture: E. urophyla, E. grandis and E. camaldulensis. All genotypes exhibited similar water potential when the 90% stomatal closure (Ψgs90) occurs with Ψgs90 always preceding the start of embolism events. The drought-tolerant hybrid showed a higher leaf resistance to embolism, but the leaf hydraulic efficiency was similar among all genotypes. Other traits presented by the drought-tolerant hybrid were a higher cell wall reinforcement, lower value of osmotic potential at full turgor and greater bulk modulus of elasticity. We also identified that the leaf capacitance after the turgor loss, the ratio between cell wall thickness (t) and lumen breadth (b) ratio (t/b)3, and the minimal conductance might be good proxies for screening drought-tolerant Eucalyptus genotypes. Our findings suggest that xylem resistance to embolism can be an important component of drought tolerance in Eucalyptus in addition to other traits aimed at delaying the development of high tensions in the xylem. Highlight Drought tolerance in tropical Eucalyptus hybrids encompasses a high leaf resistance to embolism and a suite of traits aimed at delaying the development of high tensions in the xylem.

Rare case of migration and perforation of the urinary bladder by ventriculoperitoneal shunt catheter with intravesical knotted formation: A case report and literature review.

Background: The most commonly used technique in the management of hydrocephalus is a neurosurgical procedure, known as ventriculoperitoneal shunt (VPS). Several complications of the distal end of a VPS catheter have been described in the literature, although migration and erosive bladder perforation of this shunt are extremely uncommon. Case Description: We relate a rare pediatric case of a 4-year-old boy, with long-term dysuria, intermittent incontinence, and chronic abdominal pain developed during a myelomeningocele postoperative period, without other symptoms. A bladder fistula with the distal end of the VPS inside the bladder was observed while performing an ultrasound to investigate the urinary tract. Two months before the current surgical approach, the patient, with hydrocephalus and alterations compatible with Chiari malformation, was treated with VPS and subsequently subjected to the third ventriculostomy. The child was unsuccessfully treated with an infraumbilical laparotomy, with section and careful traction of the catheter. A vesicostomy was then performed and the catheter was observed to form an intravesical knot. Conclusion: The intravesical knot formation is extremely rare and its mechanism of formation is still not well understood. Patients with VPS need adequate medical follow-up to identify possible complications of the shunt.

Impaired auxin signaling increases vein and stomatal density but reduces hydraulic efficiency and ultimately net photosynthesis.

Auxins are known to regulate xylem development in plants, but their effects on water transport efficiency are poorly known. Here we used tomato plants with the diageotropica mutation (dgt), which has impaired function of a cyclophilin 1 cis-trans isomerase involved in auxin signaling, and the corresponding wild type (WT) to explore the mutation's effects on plant hydraulics and leaf gas exchange. The xylem of the dgt mutant showed a reduced hydraulically weighted vessel diameter (Dh) (24-43%) and conduit number (25-58%) in petioles and stems, resulting in lower theoretical hydraulic conductivities (Kt); on the other hand, no changes in root Dh and Kt were observed. The measured stem and leaf hydraulic conductances of the dgt mutant were lower (up to 81%), in agreement with the Kt values; however, despite dgt and WT plants showing similar root Dh and Kt, the measured root hydraulic conductance of the dgt mutant was 75% lower. The dgt mutation increased the vein and stomatal density, which could potentially increase photosynthesis. Nevertheless, even though it had the same photosynthetic capacity as WT plants, the dgt mutant showed a photosynthetic rate c. 25% lower, coupled with a stomatal conductance reduction of 52%. These results clearly demonstrate that increases in minor vein and stomatal density only result in higher leaf gas exchange when accompanied by higher hydraulic efficiency.

The Role of Plant-Associated Bacteria, Fungi, and Viruses in Drought Stress Mitigation.

Drought stress is an alarming constraint to plant growth, development, and productivity worldwide. However, plant-associated bacteria, fungi, and viruses can enhance stress resistance and cope with the negative impacts of drought through the induction of various mechanisms, which involve plant biochemical and physiological changes. These mechanisms include osmotic adjustment, antioxidant enzyme enhancement, modification in phytohormonal levels, biofilm production, increased water and nutrient uptake as well as increased gas exchange and water use efficiency. Production of microbial volatile organic compounds (mVOCs) and induction of stress-responsive genes by microbes also play a crucial role in the acquisition of drought tolerance. This review offers a unique exploration of the role of plant-associated microorganisms-plant growth promoting rhizobacteria and mycorrhizae, viruses, and their interactions-in the plant microbiome (or phytobiome) as a whole and their modes of action that mitigate plant drought stress.

Aggregation-Induced Emission and Temperature-Dependent Luminescence of Potassium Perylenetetracarboxylate.

Investigation of temperature-dependent photoluminescent properties of potassium perylene-3,4,9,10-tetracarboxylate (K4PTC), a molecule with no internal rotational degrees of freedom, shows aggregation-induced enhanced emission at room temperature. The different excitonic emission processes are dependent of temperature, some of which quenches in an intermediate temperature range (from 50 to 150 K). The exciton excited states switching phenomenon from "dark" to "bright" states is observed and its explained using Herzberg-Teller selection rule. K4PTC is a molecule comparable to the size of its precursor, perylene-3,4,9,10-tetracarboxylic anhydride (PTCDA) and is highly soluble in water, contrary to PTCDA, which is poorly soluble in most solvents. Powder x-ray diffraction measurements corroborate a lesser degree of ordering of bulk K4PTC compared to bulk PTCDA. The green luminescent molecule could, in principle, be used as a biomarker, or in photodynamic therapy, if further studies show relatively low toxicity.

The Lanata trichome mutation increases stomatal conductance and reduces leaf temperature in tomato.

Trichomes are epidermal structures with a large variety of ecological functions and economic applications. Glandular trichomes produce a rich repertoire of secondary metabolites, whereas non-glandular trichomes create a physical barrier on the epidermis: both operate in tandem against biotic and abiotic stressors. A deeper understanding of trichome development and function would enable the breeding of more resilient crops. However, little is known about the impact of altered trichome density on leaf photosynthesis, gas exchange and energy balance. Previous work has compared multiple, closely related species differing in trichome density. Here, we analysed monogenic trichome mutants in the same tomato genetic background (Solanum lycopersicum cv. 'Micro-Tom'). We determined growth parameters, leaf spectral properties, gas exchange and leaf temperature in the hairs absent (h), Lanata (Ln) and Woolly (Wo) trichome mutants. Shoot dry weight, leaf area, leaf spectral properties and cuticular conductance were not affected by the mutations. However, the Ln mutant showed increased net carbon assimilation rate (An), associated with higher stomatal conductance (gs), with no differences in stomatal density or stomatal index between genotypes. Leaf temperature was furthermore reduced in Ln in the hottest, early hours of the afternoon. We show that a single monogenic mutation that modifies trichome density, a desirable trait for crop breeding, concomitantly improves leaf gas exchange and reduces leaf temperature.