Search

Purpose: Hyperpolarized 129Xe MRI benefits from non‐Cartesian acquisitions that sample k‐space efficiently and rapidly. However, their reconstructions are complex and burdened by decay processes unique to hyperpolarized gas. Currently used gridded reconstructions are prone to artifacts caused by magnetization decay and are ill‐suited for undersampling. We present a compressed sensing (CS) reconstruction approach that incorporates magnetization decay in the forward model, thereby producing images with increased sharpness and contrast, even in undersampled data. Methods: Radio‐frequency, T1, and T2*$$ {\mathrm{T}}_2^{\ast } $$ decay processes were incorporated into the forward model and solved using iterative methods including CS. The decay‐modeled reconstruction was validated in simulations and then tested in 2D/3D‐spiral ventilation and 3D‐radial gas‐exchange MRI. Quantitative metrics including apparent‐SNR and sharpness were compared between gridded, CS, and twofold undersampled CS reconstructions. Observations were validated in gas‐exchange data collected from 15 healthy and 25 post‐hematopoietic‐stem‐cell‐transplant participants. Results: CS reconstructions in simulations yielded images with threefold increases in accuracy. CS increased sharpness and contrast for ventilation in vivo imaging and showed greater accuracy for undersampled acquisitions. CS improved gas‐exchange imaging, particularly in the dissolved‐phase where apparent‐SNR improved, and structure was made discernable. Finally, CS showed repeatability in important global gas‐exchange metrics including median dissolved‐gas signal ratio and median angle between real/imaginary components. Conclusion: A non‐Cartesian CS reconstruction approach that incorporates hyperpolarized 129Xe decay processes is presented. This approach enables improved image sharpness, contrast, and overall image quality in addition to up‐to threefold undersampling. This contribution benefits all hyperpolarized gas MRI through improved accuracy and decreased scan durations. [ABSTRACT FROM AUTHOR]

Increasing seawater influence in coastal areas is an ongoing environmental issue. Gardening is a widespread activity mainly in touristic areas such as the Mediterranean coasts. However, the use of exotic species well adapted to salinity encompasses the risk of invasive species introduction. This study aimed to evaluate salinity tolerance of native geophytes, Pancratium maritimum L. and Eryngium maritimum L., to assess their use as ornamental species in salt affected coastal areas. Experiments were conducted using cultivated plants for flowering response and physiological and enzymatic antioxidant response. Six treatments were applied for two months, exposing plants to seawater (SW) dilutions (Tap-Water, 6.25%SW, 12.5%SW, 25%SW, 50%SW and 100%SW). Taxa decreased inflorescence production being this effect more architectonical in E. maritimum and affecting all inflorescence integrity in P. maritimum. Flowering time was strongly delayed and reduced in P. maritimum, while E. maritimum showed smaller effects among treatments. Physiological and biochemical response showed at moderate salinity levels (1/4SW) variation concomitant with late stress response and senescence in P. maritimum, with decreased water use efficiency, NPQ values, and enzymatic activity, and increased malondialdehyde (MDA) levels. In contrast, E. maritimum showed early stress response with steady gas exchange response, increasing NPQ values and catalase (CAT) and superoxide dimutase (SOD) activity, and decreasing MDA levels with salinity. Glutathione enzymes showed limited participation in both species. The results of this study suggest that neither species can be classified as halophytes, but they exhibit tolerance to low and moderate salinity levels, making them suitable for ornamental use. [ABSTRACT FROM AUTHOR]

Improving the efficiency of the legume–rhizobia symbiosis in African soils for increased grain yield would require the use of highly effective strains capable of nodulating a wide range of legume plants. This study assessed the photosynthetic functioning, N2 fixation, relative symbiotic effectiveness (%RSE) and C assimilation of 22 jack bean (Canavalia ensiformis L.) microsymbionts in Eswatini soils as a first step to identifying superior isolates for inoculant production. The results showed variable nodule number, nodule dry matter, shoot biomass and photosynthetic rates among the strains tested under glasshouse conditions. Both symbiotic parameters and C accumulation differed among the test isolates at the shoot, root and whole-plant levels. Although 7 of the 22 jack bean isolates showed much greater relative symbiotic efficiency than the commercial Bradyrhizobium strain XS21, only one isolate (TUTCEeS2) was statistically superior to the inoculant strain, which indicates its potential for use in inoculant formulation after field testing. Furthermore, the isolates that recorded high %RSE elicited greater amounts of fixed N. [ABSTRACT FROM AUTHOR]

Background: in COVID-19 acute respiratory failure, the effects of CPAP and FiO2 on respiratory effort and lung stress are unclear. We hypothesize that, in the compliant lungs of early Sars-CoV-2 pneumonia, the application of positive pressure through Helmet-CPAP may not decrease respiratory effort, and rather worsen lung stress and oxygenation when compared to higher FiO2 delivered via oxygen masks. Methods: In this single-center (S.Luigi Gonzaga University-Hospital, Turin, Italy), randomized, crossover study, we included patients receiving Helmet-CPAP for early (< 48 h) COVID-19 pneumonia without additional cardiac or respiratory disease. Healthy subjects were included as controls. Participants were equipped with an esophageal catheter, a non-invasive cardiac output monitor, and an arterial catheter. The protocol consisted of a random sequence of non-rebreather mask (NRB), Helmet-CPAP (with variable positive pressure and FiO2) and Venturi mask (FiO2 0.5), each delivered for 20 min. Study outcomes were changes in respiratory effort (esophageal swing), total lung stress (dynamic + static transpulmonary pressure), gas-exchange and hemodynamics. Results: We enrolled 28 COVID-19 patients and 7 healthy controls. In all patients, respiratory effort increased from NRB to Helmet-CPAP (5.0 ± 3.7 vs 8.3 ± 3.9 cmH2O, p < 0.01). However, Helmet's pressure decreased by a comparable amount during inspiration (− 3.1 ± 1.0 cmH2O, p = 0.16), therefore dynamic stress remained stable (p = 0.97). Changes in static and total lung stress from NRB to Helmet-CPAP were overall not significant (p = 0.07 and p = 0.09, respectively), but showed high interpatient variability, ranging from − 4.5 to + 6.1 cmH2O, and from − 5.8 to + 5.7 cmH2O, respectively. All findings were confirmed in healthy subjects, except for an increase in dynamic stress (p < 0.01). PaO2 decreased from NRB to Helmet-CPAP with FiO2 0.5 (107 ± 55 vs 86 ± 30 mmHg, p < 0.01), irrespective of positive pressure levels (p = 0.64). Conversely, with Helmet's FiO2 0.9, PaO2 increased (p < 0.01), but oxygen delivery remained stable (p = 0.48) as cardiac output decreased (p = 0.02). When PaO2 fell below 60 mmHg with VM, respiratory effort increased proportionally (p < 0.01, r = 0.81). Conclusions: In early COVID-19 pneumonia, Helmet-CPAP increases respiratory effort without altering dynamic stress, while the effects upon static and total stress are variable, requiring individual assessment. Oxygen masks with higher FiO2 provide better oxygenation with lower respiratory effort. Trial registration Retrospectively registered (13-May-2021): clinicaltrials.gov (NCT04885517), https://clinicaltrials.gov/ct2/show/NCT04885517. [ABSTRACT FROM AUTHOR]

Cyanidioschyzonmerolae is an extremophilic red microalga which grows in low-pH, high-temperature environments. The basis of C. merolae's environmental resilience is not fully characterized, including whether this alga uses a carbon-concentrating mechanism (CCM). To determine if C. merolae uses a CCM, we measured CO2 uptake parameters using an open-path infra-red gas analyzer and compared them to values expected in the absence of a CCM. These measurements and analysis indicated that C. merolae had the gas-exchange characteristics of a CCM-operating organism: low CO2 compensation point, high affinity for external CO2, and minimized rubisco oxygenation. The biomass δ13C of C. merolae was also consistent with a CCM. The apparent presence of a CCM in C. merolae suggests the use of an unusual mechanism for carbon concentration, as C. merolae is thought to lack a pyrenoid and gas-exchange measurements indicated that C. merolae primarily takes up inorganic carbon as carbon dioxide, rather than bicarbonate. We use homology to known CCM components to propose a model of a pH-gradient-based CCM, and we discuss how this CCM can be further investigated. [ABSTRACT FROM AUTHOR]

Recent climate extremes in Mongolia have ignited a renewed interest in understanding past climate variability over centennial and longer time scales across north-central Asia. Tree-ring width records have been extensively studied in Mongolia as proxies for climate reconstruction, however, the climate and environmental signals of tree-ring stable isotopes from this region need to be further explored. Here, we evaluated a 182-year record of tree-ring δ13C and δ18O from Siberian Pine (Pinus sibirica Du Tour) from a xeric site in central Mongolia (Khorgo Lava) to elucidate the environmental factors modulating these parameters. First, we analyzed the climate sensitivity of tree-ring δ13C and δ18O at Khorgo Lava for comparison with ring-width records, which have been instrumental in reconstructing hydroclimate in central Mongolia over two millennia. We also compared stable isotope records of trees with partial cambial dieback ('strip-bark morphology'), a feature of long-lived conifers growing on resource-limited sites, and trees with a full cambium ('whole-bark morphology'), to assess the inferred leaf-level physiological behavior of these trees. We found that interannual variability in tree-ring δ13C and δ18O reflected summer hydroclimatic variability, and captured recent, extreme drought conditions, thereby complementing ring-width records. The tree-ring δ18O records also had a spring temperature signal and thus expanded the window of climate information recorded by these trees. Over longer time scales, strip-bark trees had an increasing trend in ring-widths, δ13C (and intrinsic water-use efficiency, iWUE) and δ18O, relative to whole-bark trees. Our results suggest that increases in iWUE at this site might be related to a combination of leaf-level physiological responses to increasing atmospheric CO2, recent drought, and stem morphological changes. Our study underscores the potential of stable isotopes for broadening our understanding of past climate in north-central Asia. However, further studies are needed to understand how stem morphological changes might impact stable isotopic trends. [ABSTRACT FROM AUTHOR]

BackgroundExisting methods for directly measuring photosynthetic capacity (Amax) have low throughput, which creates a key bottleneck for pre-breeding and ecological research. Currently available commercial leaf gas exchange systems are not designed to maximize throughput, on either a cost or time basis.ResultsWe present a novel multiplexed semi-portable gas exchange system, OCTOflux, that can measure Amax with approximately 4-7 times the throughput of commercial devices, despite a lower capital cost. The main time efficiency arises from having eight leaves simultaneously acclimate to saturating CO2 and high light levels; the long acclimation periods for each leaf (13.8 min on average in this study) thus overlap to a large degree, rather than occurring sequentially. The cost efficiency arises partly from custom-building the system and thus avoiding commercial costs like distribution, marketing and profit, and partly from optimizing the system's design for Amax throughput rather than flexibility for other types of measurements.ConclusionThroughput for Amax measurements can be increased greatly, on both a cost and time basis, by multiplexing gas streams from several leaf chambers connected to a single gas analyzer. This can help overcome the bottleneck in breeding and ecological research posed by limited phenotyping throughput for Amax.

The evolution of hemoglobin function in the transition from water‐ to air‐breathing has been highly debated but remains unresolved. Here, we characterized the hemoglobin function in five closely related water‐ and air‐breathing catfishes. We identify distinct directions of hemoglobin evolution in the clades that evolved air‐breathing, and we show strong selection on hemoglobin function within the catfishes. These findings show that the lack of a general direction in hemoglobin function in the transition from water‐ to air‐breathing may have resulted from divergent selection on hemoglobin function in independent clades of air‐breathing fishes. Research highlights: 1.We show that the evolution of air‐breathing resulted in distinct changes in hemoglobin function.2.This illustrates that the adaptations to air‐breathing cannot be generalized across independent groups of air‐breathing fishes. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rice (Oryza sativa) is a water-intensive crop, and like other plants uses stomata to balance CO2 uptake with water-loss. To identify agronomic traits related to rice stomatal complexes, an anatomical screen of 64 Thai and 100 global rice cultivars was undertaken. Epidermal outgrowths called papillae were identified on the stomatal subsidiary cells of all cultivars. These were also detected on eight other species of the Oryza genus but not on the stomata of any other plant species we surveyed. Our rice screen identified two cultivars that had “mega-papillae” that were so large or abundant that their stomatal pores were partially occluded; Kalubala Vee had extra-large papillae, and Dharia had approximately twice the normal number of papillae. These were most accentuated on the flag leaves, but mega-papillae were also detectable on earlier forming leaves. Energy dispersive X-Ray spectrometry revealed that silicon is the major component of stomatal papillae. We studied the potential function(s) of mega-papillae by assessing gas exchange and pathogen infection rates. Under saturating light conditions, mega-papillae bearing cultivars had reduced stomatal conductance and their stomata were slower to close and re-open, but photosynthetic assimilation was not significantly affected. Assessment of an F3 hybrid population treated with Xanthomonas oryzae pv. oryzicola indicated that subsidiary cell mega-papillae may aid in preventing bacterial leaf streak infection. Our results highlight stomatal mega-papillae as a novel rice trait that influences gas exchange, stomatal dynamics, and defense against stomatal pathogens which we propose could benefit the performance of future rice crops.

Rice (Oryza sativa) is a water-intensive crop, and like other plants uses stomata to balance CO2 uptake with water-loss. To identify agronomic traits related to rice stomatal complexes, an anatomical screen of 64 Thai and 100 global rice cultivars was undertaken. Epidermal outgrowths called papillae were identified on the stomatal subsidiary cells of all cultivars. These were also detected on eight other species of the Oryza genus but not on the stomata of any other plant species we surveyed. Our rice screen identified two cultivars that had "mega-papillae" that were so large or abundant that their stomatal pores were partially occluded; Kalubala Vee had extra-large papillae, and Dharia had approximately twice the normal number of papillae. These were most accentuated on the flag leaves, but mega-papillae were also detectable on earlier forming leaves. Energy dispersive X-Ray spectrometry revealed that silicon is the major component of stomatal papillae. We studied the potential function(s) of mega-papillae by assessing gas exchange and pathogen infection rates. Under saturating light conditions, mega-papillae bearing cultivars had reduced stomatal conductance and their stomata were slower to close and re-open, but photosynthetic assimilation was not significantly affected. Assessment of an F3 hybrid population treated with Xanthomonas oryzae pv. oryzicola indicated that subsidiary cell mega-papillae may aid in preventing bacterial leaf streak infection. Our results highlight stomatal mega-papillae as a novel rice trait that influences gas exchange, stomatal dynamics, and defense against stomatal pathogens which we propose could benefit the performance of future rice crops. [ABSTRACT FROM AUTHOR]

Purpose: This study develops a tracer kinetic model of xenon uptake in the human brain to determine the transfer rate of inhaled hyperpolarized 129Xe from cerebral blood to gray matter that accounts for the effects of cerebral physiology, perfusion and magnetization dynamics. The 129Xe transfer rate is expressed using a tracer transfer coefficient, which estimates the quantity of hyperpolarized129Xe dissolved in cerebral blood under exchange with depolarized129Xe dissolved in gray matter under equilibrium of concentration. Theory and Methods: Time‐resolved MR spectra of hyperpolarized 129Xe dissolved in the human brain were acquired from three healthy volunteers. Acquired spectra were numerically fitted with five Lorentzian peaks in accordance with known 129Xe brain spectral peaks. The signal dynamics of spectral peaks for gray matter and red blood cells were quantified, and correction for the 129Xe T1 dependence upon blood oxygenation was applied. 129Xe transfer dynamics determined from the ratio of the peaks for gray matter and red blood cells was numerically fitted with the developed tracer kinetic model. Results: For all the acquired NMR spectra, the developed tracer kinetic model fitted the data with tracer transfer coefficients between 0.1 and 0.14. Conclusion: In this study, a tracer kinetic model was developed and validated that estimates the transfer rate of HP 129Xe from cerebral blood to gray matter in the human brain. [ABSTRACT FROM AUTHOR]

The paper shows that creation of materials with antibacterial and antifungal action presupposes an introduction of additives in them. One of the directions concerning fight against mold fungi is an inclusion of biocide additives having vegetable origin in structure of polymer materials used for manufacturing packing products. The main mission of anti-microbial additives is reduction of microbe amount in product mass and on its surface. Activity of anti-microbial compounds depends on the following parameters: concentration of active component, pH, temperature, polymer type, introduction method (with plasticizer or in melting state) and time period of their contact with polymer. In addition it is necessary to take into account such not unimportant factor as sensitivity of micro-organisms. Modern film polymer materials ensure only a certain level of product protection. They can not targetedly affect biochemical and microbiological changes in a packing product. It is necessary to develop new packing materials with selective permeability that create a barrier on the way of extremely intensive gas and moisture exchange, outside microflora flow, and prevent an evolution of undesired micro-organisms on packing products. Polymers have been selected as a basis for a bactericide packing material. Investigations have shown that composition including PEHP 98% (polyethylene of high pressure) + DGR (disproportionate gum rosin) + DETA (diethylenetriamine) has inhibited (hindered) sufficiently in a good way growth of mold fungi and PEHP composition with additives of tallow pitch and polyethylenepolyamine has demonstrated a rapid deterioration of strength characteristics and an increase in additive of the supposed mixture including pine oleoresin (POR) with DETA and DGR (with DETA more than 2%) hinders rapidly strength material characteristics.

When measuring photosynthesis in mosses, the non-photosynthetic (brown) sections are usually removed and only the green sections are measured. However, how this pretreatment affects photosynthesis rates is unclear. Therefore, we studied the effect of removing the non-photosynthetic sections in three moss species with distinct morphological and stem-anatomical structures, comparing net CO2 assimilation rates (AN) of detached green and brown sections to those of intact shoots. Right after separation, the summed AN of the separated sections was significantly lower than those of the intact shoots for Pogonatum nudiusculum Mitt. and Pleuroziopsis ruthenica (Weinm.) Kindb. ex E. Britton, while no significant difference was found for Actinothuidium hookeri (Mitt.) Broth. However, AN recovered within a day, and the progressive reduction of AN expected if carbonsink removal was an important mechanism was not observed. Our study indicates that removal of non-photosynthetic sections results in an underestimation of the photosynthetic capacity of the green moss sections, but only for the species with relatively complex internal transport structures, and only immediately after the separation. The fast and transient response suggests a mechanism via an electrical signal induced by wounding or reduced hydraulic integrity, rather than through a reduced carbon-sink strength. More comprehensive investigations on signaling and other mechanisms regulating moss photosynthesis will contribute to more accurate measurement methods as well as a deeper understanding of moss ecophysiology and the contribution of mosses to carbon fluxes in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

It is common practice to manipulate CO2 and O2 mole fraction during gas‐exchange experiments to suppress or exacerbate photorespiration, or simply carry out CO2 response curves. In doing so, it is implicitly assumed that metabolic pathways other than carboxylation and oxygenation are altered minimally. In the past few years, targeted metabolic analyses have shown that this assumption is incorrect, with changes in the tricarboxylic acid cycle, anaplerosis (phosphoenolpyruvate carboxylation), and nitrogen or sulphur assimilation. However, this problem has never been tackled systematically using non‐targeted analyses to embrace all possible affected metabolic pathways. Here, we exploited combined NMR, GC–MS, and LC–MS data and conducted non‐targeted analyses on sunflower leaves sampled at different O2/CO2 ratios in a gas exchange system. The statistical analysis of nearly 4,500 metabolic features not only confirms previous findings on anaplerosis or S assimilation, but also reveals significant changes in branched chain amino acids, phenylpropanoid metabolism, or adenosine turn‐over. Noteworthy, all of these pathways involve CO2 assimilation or liberation and thus affect net CO2 exchange. We conclude that manipulating CO2 and O2 mole fraction has a broad effect on metabolism, and this must be taken into account to better understand variations in carboxylation (anaplerotic fixation) or apparent day respiration. It is generally assumed that metabolic pathways other than carboxylation and oxygenation are altered minimally by changing CO2 and O2 conditions during gas exchange. Using isotope‐assisted metabolomics analyses, we show that manipulating CO2 and O2 has a broad effect on different major metabolic pathways, and this must be taken into to better interpret variations in carboxylation (anaplerotic fixation) or apparent day respiration. [ABSTRACT FROM AUTHOR]

Abstract Background Existing methods for directly measuring photosynthetic capacity (A max) have low throughput, which creates a key bottleneck for pre-breeding and ecological research. Currently available commercial leaf gas exchange systems are not designed to maximize throughput, on either a cost or time basis. Results We present a novel multiplexed semi-portable gas exchange system, OCTOflux, that can measure A max with approximately 4–7 times the throughput of commercial devices, despite a lower capital cost. The main time efficiency arises from having eight leaves simultaneously acclimate to saturating CO2 and high light levels; the long acclimation periods for each leaf (13.8 min on average in this study) thus overlap to a large degree, rather than occurring sequentially. The cost efficiency arises partly from custom-building the system and thus avoiding commercial costs like distribution, marketing and profit, and partly from optimizing the system’s design for A max throughput rather than flexibility for other types of measurements. Conclusion Throughput for A max measurements can be increased greatly, on both a cost and time basis, by multiplexing gas streams from several leaf chambers connected to a single gas analyzer. This can help overcome the bottleneck in breeding and ecological research posed by limited phenotyping throughput for A max.

A system for the shipboard measurement of air-sea CO2 fluxes by eddy covariance was developed and tested. The system was designed to reduce two major sources of experimental uncertainty previously reported. First, the correction for in situ water vapor fluctuations (the “Webb” correction) was reduced by 97% by drying the air sample stream. Second, motion sensitivity of the gas analyzer was reduced by using an open-path type sensor that was converted to a closed-path configuration to facilitate drying of the air stream. High-quality CO2 fluxes were obtained during 429 14 min flux intervals during two cruises in the North Atlantic. The results suggest that the gas analyzer resolved atmospheric CO2 fluctuations well below its RMS noise level. This noise was uncorrelated with the vertical wind and therefore filtered out by the flux calculation. Using climatological data, we estimate that the techniques reported here could enable high-quality measurements of air-sea CO2 flux over much of the world oceans.

Strawberry and wild strawberry are among the most popular horticultural crops. Due to the development of soilless cultivation systems, the whole-year production of these economically important fruit crops is achievable even in countries with temperate climate. However, the responses of strawberry (Fragaria × ananassa Duch.) and wild strawberry (Fragaria vesca L.) to microclimate conditions in greenhouse gutter cultivation in the autumn–winter season in Poland have not been yet determined. The aim of this study was to analyze the physiological, biochemical, and biometrical responses of two cultivars of strawberry ‘Ostara’ and ‘San Andreas’ and two cultivars of wild strawberry ‘Baron von Solemacher’ and ‘Regina’ grown for 20 weeks, starting from September 17th, in controlled greenhouse conditions on coconut mats in gutters in the autumn–winter season and irradiated with sodium lamps. Strawberry ‘San Andreas’ produced 30% larger leaves and almost three-fold higher fresh and dry weight of biomass than ‘Ostara’. The strawberry plants ‘San Andreas’ had a higher content (20%) of chlorophyll a and 30% of chlorophyll b than ‘Ostara’ plants. Generally, ‘San Andreas’ displayed an overall higher concentration of intercellular CO2 (about 14%) than ‘Ostara’ plants providing higher gas exchange processes. Photosynthetic rate amounted to 13.0 μmol·m−2·s−1 for ‘San Andreas’ that was almost two-fold higher than for ‘Ostara’. ‘San Andreas’ flower and fruit productions were uniform and the six-fold higher individual fruit yield proved the excellent attributes of this cultivar to the greenhouse cultivation. Even though the productivity of the two studied wild strawberry cultivars was similar, ‘Regina’ showed higher values of some parameters than ‘Baron von Solemacher’ (40% larger leaves, 25% higher photosynthetic rate, 10% higher concentration of intercellular CO2). A high nutritional value of fruits is maintained compared to traditional open-air cultivation.

Summary: It has been suggested that plant carbon (C) use by symbiotic arbuscular mycorrhizal fungi (AMF) may be compensated by higher photosynthetic rates because fungal metabolism creates a strong C sink that prevents photosynthate accumulation and downregulation of photosynthesis. This mechanism remains largely unexplored and lacks experimental evidence.We report here two experiments showing that the experimental manipulation of the mycorrhizal C sink significantly affected the photosynthetic rates of cucumber host plants. We expected that a sudden reduction in sink strength would cause a significant reduction in photosynthetic rates, at least temporarily.Excision of part of the extraradical mycorrhizal mycelium from roots, and causing no disturbance to the plant, induced a sustained (10–40%) decline in photosynthetic rates that lasted from 30 min to several hours in plants that were well‐nourished and hydrated, and in the absence of growth or photosynthesis promotion by mycorrhizal inoculation. This effect was though minor in plants growing at high (700 ppm) atmospheric CO2.This is the first direct experimental evidence for the C sink strength effects exerted by arbuscular mycorrhizal symbionts on plant photosynthesis. It encourages further experimentation on mycorrhizal source–sink relations, and may have strong implications in large‐scale assessments and modelling of plant photosynthesis. [ABSTRACT FROM AUTHOR]

Plant simulation models are abstractions of plant physiological processes that are useful for investigating the responses of plants to changes in the environment. Because photosynthesis and transpiration are fundamental processes that drive plant growth and water relations, a leaf gas-exchange model that couples their interdependent relationship through stomatal control is a prerequisite for explanatory plant simulation models. Here, we present a coupled gas-exchange model for C4 leaves incorporating two widely used stomatal conductance submodels: Ball–Berry and Medlyn models. The output variables of the model includes steady-state values of CO2 assimilation rate, transpiration rate, stomatal conductance, leaf temperature, internal CO2 concentrations, and other leaf gas-exchange attributes in response to light, temperature, CO2, humidity, leaf nitrogen, and leaf water status. We test the model behavior and sensitivity, and discuss its applications and limitations. The model was implemented in Julia programming language using a novel modeling framework. Our testing and analyses indicate that the model behavior is reasonably sensitive and reliable in a wide range of environmental conditions. The behavior of the two model variants differing in stomatal conductance submodels deviated substantially from each other in low humidity conditions. The model was capable of replicating the behavior of transgenic C4 leaves under moderate temperatures as found in the literature. The coupled model, however, underestimated stomatal conductance in very high temperatures. This is likely an inherent limitation of the coupling approaches using Ball–Berry type models in which photosynthesis and stomatal conductance are recursively linked as an input of the other.

Flowers are likely to be under various selective pressures not limited to reproduction and resource trade-offs. Here, we investigate the physiological responses (conductance, transpiration and respiration) of flowers under augmented temperature and supplemental watering, link these responses to actual flower longevity, and search for evidence of adaptive plasticity. Flower maintenance costs and plant fitness were investigated using the Andean geophyte, Rhodolirium montanum , in a manipulative field experiment. Maintenance determined by gas exchange was measured on fully expanded tepals; along with flower duration and its components, opening and closing. Fitness measured by fruit and seed production and seed set (mature/total) was examined. We artificially increased temperature and supplementally watered plants. Our study showed that flower longevity decreased under drier conditions, but the effect on flower opening and closing was even stronger, both of which advanced under higher temperatures without supplemental watering. Gas exchange also decreased, limiting water loss, under drier, warmer conditions. Those plants that reduced flower longevity under warming had higher total seed production and seed set. Plants that reduced conductance under warmed conditions also had higher seed set. These results suggest that plants are plastically optimizing fitness by reducing flower maintenance costs. Possible flower longevity and fitness connotations of our results under climate change are discussed. [ABSTRACT FROM AUTHOR]

Although grafting has become an effective tool to enhance many traits in horticultural crops, its role in improving the performance of local landraces is yet to be proven. The aim of this work was to assess the performance of the ‘Ramellet’ tomato, a landrace from the Balearic Islands, when grafted onto different rootstocks. For this purpose, two ‘Ramellet’ genotypes were grafted on two commercial (‘Beaufort’ and ‘Maxifort’) and a wild ( Solanum pimpinellifolium ) tomato rootstock species, and cultivated in greenhouse under commercial conditions. Plant yield, morphology and photosynthetic traits were measured in all combinations, with non-grafted and self-grafted ‘Ramellet’ plants used as controls. A significant effect of the rootstock on key parameters related to yield, plant growth and photosynthesis was found in both ‘Ramellet’ genotypes. Stomatal conductance increased, resulting in a decreased water-use efficiency in both genotypes grafted on the commercial rootstocks. Oppositely, when grafted on S. pimpinellifolium , stomatal conductance decreased and water-use efficiency increased in one of the ‘Ramellet’ genotypes. Remarkably, there was a significant correlation between water-use efficiency, plant growth and yield. Overall, the results highlight the potential of grafting to alter several physiological traits of local landraces and to provide new clues towards advancing our understanding in the underlying determinants of water-use efficiency and plant yield. [ABSTRACT FROM AUTHOR]

Leaf scald caused by Monographella albescens reduces the photosynthetic area, causing yield losses in rice. This study investigated the efficacy of the rhizobacteria Burkholderia pyrrocinia (BRM-32113) and Pseudomonas fluorescens (BRM-32111), combined with silicon (Si) fertilization, to reduce lesion size and the area under the disease progress curve (AUDPC), as well as to minimize the negative effects on gas exchange, chlorophyll a fluorescence, chlorophyll content and the activity of oxidative stress enzymes. The experiment used a completely randomized design with four replications and seven treatments. Compared with plants only fertilized with Si, plants fertilized with Si and treated with BRM-32113 showed reductions of 22% in scald lesion expansion and 37% in AUDPC, a 27% increase in the rate of CO2 assimilation ( A), a 33% decrease in the internal CO2 concentration ( Ci), and a 40% increase in ascorbate peroxidase activity. It was therefore concluded that the combination of BRM-32113 with Si fertilization reduces the severity of leaf scald, protecting the photosynthetic apparatus, thus representing a sustainable method of reducing the loss of income caused by leaf scald in rice. [ABSTRACT FROM AUTHOR]

The enzyme carbonic anhydrase (CA) has well-known functions in acid-base balance, respiratory gas exchange, and osmoregulation in teleost fishes. However, studies concerning the role of CA in elasmobranchs are still scarce. Therefore, the aim of this study is to present the current status of CA studies in sharks and rays, as well as to identify gaps and emerging needs, in order to guide future studies. This review is organized according to the main roles of CA, with further considerations on climate change and CA effects indicated as paramount, as strategies in the face of climate change can be crucial for species response. The literature review revealed a reduction in publications on CA over the years. In addition, a historical research differentiation is noted, where the first assessments on the subject addressed investigations on basic CA functions, while the most recent studies present a comparative approach among species as well as interdisciplinary discussions, such as ecology and phylogeny. Considering that several elasmobranchs are threatened, future studies should prioritize non-lethal methodologies, in addition to expanding studies to climate change effects on CA. [Display omitted] • Elasmobranch carbonic anhydrase studies have declined over the decades. • Osmoregulation is the most studied role involving Carbonic Anhydrase. • Most elasmobranchs did have not yet been assessed regarding carbonic anhydrase. • Environmental alterations, such as climate change and pollution affect this enzyme. [ABSTRACT FROM AUTHOR]

In this study, the effect of Super-AB-A-200 polymer on salt and drought resistance of Eucalyptus globulus Labill. was evaluated. The treatments were: (1) Control, Control + polymer; (2) NaCl, NaCl+ polymer; (3) Drought, Drought + polymer; (4) Drought + NaCl, Drought + NaCl + polymer. The results showed that Super-AB-A-200 in root medium helped E. globulus cuttings to resist the salinity and drought stresses, because of the following reasons: (1) E. globulus roots absorbed the held water from Super-AB-A-200 polymer in soil water-deficit conditions; (2) in saline conditions, Super-AB-A-200 retained Cl- and Na+ in the soil solution because of their high water-holding capability, moreover, the exchangeable K+ included in Super-AB-A-200 resulted in an amended K+/Na+ balance in salinized plants; (3) Super-AB-A-200 helped E. globulus cuttings to resist interactive effects of salinity and drought stresses, which was essentially justified by their salt- and water-holding capabilities. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of the hydrophilic polymer Super-AB-A-300 on salt and drought resistance in Eucalyptus saligna Sm. One-year-old cuttings of E. saligna were treated with salt (2 L of 300 mM NaCl), drought stress, and salt plus drought stress; an untreated set of cuttings was used as a control. All treatments were conducted with and without the Super-AB-A-300 polymer in the soil mixture. The Super-AB-A-300 polymer held more water in the soil during water-deficit conditions and promoted tolerance to salinity and drought stresses in the E. saligna rooted cuttings. In addition, the Super-AB-A-300 polymer retained Cl and Na in the soil solution due to its high water-holding capability and the exchangeable K in the Super-AB-A-300 resulted in an amended K /Na balance in the salt-treated plants. Furthermore, the Super-AB-A-300 polymer promoted greater resistance to salinity plus drought stresses, due to the salt- and water-holding capabilities of the polymer. [ABSTRACT FROM AUTHOR]

Low levels of crassulacean acid metabolism (CAM) are demonstrated in two species with C 4 photosynthesis, Portulaca cyclophylla and P. digyna. The expression of CAM in P. cyclophylla and P. digyna is facultative, i.e. optional. Well-watered plants did not accumulate acid at night and exhibited gas-exchange patterns consistent with C 4 photosynthesis. CAM-type nocturnal acidification was reversible in that it was induced following drought and lost when droughted plants were rewatered. In P. cyclophylla , droughting was accompanied by a small but discernible net uptake of CO 2 during the dark, whereas in P. digyna , net CO 2 exchange at night approached the CO 2 compensation point but did not transition beyond it. This report brings the number of known C 4 species with a capacity for expressing CAM to six. All are species of Portulaca . The observation of CAM in P. cyclophylla and P. digyna is the first for species in the opposite-leaved (OL) Portulacelloid-anatomy lineage of Portulaca and for the Australian clade therein. The other four species are within the alternate-leaved (AL) lineage, in the Atriploid-anatomy Oleracea and the Pilosoid-anatomy Pilosa clades. Studies of the evolutionary origins of C 4 and CAM in Portulaca will benefit from a more wide-range survey of CAM across its species, particularly in the C 3 -C 4 intermediate-containing Cryptopetala clade. [ABSTRACT FROM AUTHOR]

Background: Mitochondrial respiration in the dark (Rdark) is a critical plant physiological process, and hence a reliable, efficient and high-throughput method of measuring variation in rates of Rdark is essential for agronomic and ecological studies. However, currently methods used to measure Rdark in plant tissues are typically low throughput. We assessed a high-throughput automated fluorophore system of detecting multiple O2 consumption rates. The fluorophore technique was compared with O2-electrodes, infrared gas analysers (IRGA), and membrane inlet mass spectrometry, to determine accuracy and speed of detecting respiratory fluxes. Results: The high-throughput fluorophore system provided stable measurements of Rdark in detached leaf and root tissues over many hours. High-throughput potential was evident in that the fluorophore system was 10 to 26-fold faster per sample measurement than other conventional methods. The versatility of the technique was evident in its enabling: (1) rapid screening of Rdark in 138 genotypes of wheat; and, (2) quantification of rarely-assessed whole-plant Rdark through dissection and simultaneous measurements of above- and below-ground organs. Discussion: Variation in absolute Rdark was observed between techniques, likely due to variation in sample conditions (i.e. liquid vs. gas-phase, open vs. closed systems), indicating that comparisons between studies using different measuring apparatus may not be feasible. However, the high-throughput protocol we present provided similar values of Rdark to the most commonly used IRGA instrument currently employed by plant scientists. Together with the greater than tenfold increase in sample processing speed, we conclude that the high-throughput protocol enables reliable, stable and reproducible measurements of Rdark on multiple samples simultaneously, irrespective of plant or tissue type. [ABSTRACT FROM AUTHOR]

The purpose of this study is to analyze natural and anthropogenic forest ecosystems in order to establish the functional tools for ecophysiological characterization and monitoring of the investigated sites. Related to leaf traits, the parameters of foliar gas-exchange, specific leaf area (SLA), leaf dry matter content (LDMC) and carbohydrates fractions were analyzed. Four sites (riverside coppices) represented by natural forests and forestry plantations were studied and, a control area the zone with integral protection (Letea Forest, Hăşmacu Mare) was considered; all are located along the Chilia branch from Danube Delta Biosphere Reserve. In plantations, in representative species, the metabolic loss was increased by an enhanced of respiration and transpiration processes, higher than in natural forest ecosystems. Statistical analysis has found significant differences in instant water use efficiency, respiration and leaf dry matter content in species from plantations in comparison with natural forest but not so significant among natural forest and natural reserve (Letea Forest-Hăşmacu Mare) at the p <0.05, level of significance. Furthermore, the native species (Populus alba L., Salix alba L.) had a low specific leaf area (SLA) and a high leaf dry matter content (LDMC) in conditions of habitats of natural/ quasi-natural condition with a lower (semi-controlled) anthropogenic intervention and a high SLA and low LDMC in native species and hybrids poplar at cultivated plantation. The results of this study indicate that representative species are responsive to the habitat conditions indicating the disturbance of the sites and indirectly, the anthropogenic pressure. [ABSTRACT FROM AUTHOR]