Fluorescent Pigment Research Articles

Individual and interactive effects of temperature and blue light on canola growth, lignin biosynthesis and methane emissions.

It is now well documented that plants produce methane (CH4) under aerobic conditions. However, the mechanisms of methane production in plants, its potential precursors, and the factors that are involved in the process are not fully understood. Few studies have considered the effects of blue light on methane emissions from plants; however, the combined effects of temperature and blue light have not been studied. We studied the effects of two temperature regimes (22/18°C and 28/24°C; 16h light/8h dark), and three blue light levels (0, 4, and 8mWcm-2; 400-500nm) on the growth, lignin, and methane emissions of canola (Brassica napus). Plants were grown under experimental conditions for three weeks, and then methane, monolignols and other plant traits, including growth, biomass, growth index, photosynthesis, chlorophyll fluorescence, and photosynthetic pigments, were measured. Blue light significantly increased methane emissions, stem height, and growth rate, but decreased stem diameter, leaf number and area, biomass, specific leaf mass, leaf area ratio, shoot/root mass ratio, photosynthetic pigments, sinapyl alcohol, and coniferyl aldehyde. Higher temperature significantly decreased stem diameter, non-photochemical quenching, sinapyl alcohol, and coniferyl aldehyde. Methane emission was negatively correlated with plant dry mass, leaf area per plant, and maximum quantum yield of photosystem II. However, no significant relationships were found between methane and monolignols. In conclusion, plants emitted more methane under stress conditions; however, further studies are required to understand the potential precursors of methane and the mechanism of its synthesis in plants.

Occurrence of atypical Pseudomonas viridiflava strains on different host plants in southern Italy

AbstractSince 1997, severe bacterial disease symptoms were observed during surveys carried out in farms with field‐grown Molfettese Catalogna chicory (Cichorium intybus var. sylvestre, Catalogna group), sugarloaf chicory (C. intybus var. porphyreum), curly type lettuce (Lactuca sativa var. crispa) cvs Langero and Aleppo, and safflower (Carthamus tinctorius) located in the Apulia and Basilicata regions of southern Italy. Convex colonies with yellowish mucoid material on hypersucrose medium (5% sucrose nutrient agar), producing fluorescent pigments on King's medium B, were isolated from all symptomatic plants. Based on conventional biochemical and nutritional tests, Biolog assays, and analysis of partial 16S rDNA and rpoB sequences, these atypical fluorescent Pseudomonas isolates were identified as Pseudomonas viridiflava. The pathogenicity of the isolates was ascertained by artificial inoculation on their respective original hosts. The analysis of rpoB gene sequences and RAPD‐PCR profiles showed a high genetic variability among the P. viridiflava isolates. To the best of our knowledge, this is the first report of bacterial diseases on horticultural crops caused by atypical strains of P. viridiflava in Italy and the first report of the bacterium on safflower. In addition, P. viridiflava is reported for the first time as a causal agent of leaf spot on potato (Solanum tuberosum). The economic importance of chicory and curly type lettuce in southern Italy and recent spread of atypical and highly virulent P. viridiflava strains require more extensive and careful phytosanitary surveillance, as well as an adjustment of sustainable crop protection management to cope with this new challenge.

In vivo detection of spectral reflectance changes associated with regulated heat dissipation mechanisms complements fluorescence quantum efficiency in early stress diagnosis.

Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Using leaf spectroscopy, we evaluated the capability of pigment spectral unmixing to calculate the fluorescence quantum efficiency (FQE) and simultaneously retrieve fast absorption changes in a drought and nitrogen deficiency experiment with tomato. In addition, active fluorescence measurements and pigment analyses of xanthophylls, carotenes and chlorophylls were conducted. We observed notable responses in noninvasive proximal sensing-retrieved FQE values under stress, but as expected, these alone were not enough to identify the constraints in photosynthetic efficiency. Reflectance-based detection of the 535-nm peak absorption change was able to complement FQE and indicate the activation of regulated heat dissipation for both stress treatments under growing light conditions. However, further complexity in the light harvesting energy regulation needs to be accounted for when considering additional light stress. Our results underscore the potential of complementary in vivo quantitative spectroscopy-based products in the early and nondestructive stress diagnosis of plants, marking the path for further applications.

Impact of emerging pollutants mixtures on marine and brackish phytoplankton: diatom Phaeodactylum tricornutum and cyanobacterium Microcystis aeruginosa

Pharmaceuticals and ionic liquids (ILs) are emerging as significant micropollutants with environmental presence and potential ecological impacts. The possible simultaneous occurrence of these two groups of pollutants in aquatic environments raises complex challenges due to their diverse chemical properties and potential for interactive effects. Given the documented widespread presence of pharmaceuticals and the emerging concerns about ILs, the study aims to evaluate the adverse effects of binary mixtures of imidazolium ionic liquid IM1-8C(CN)3 and two representatives of pharmaceuticals: antibiotic oxytetracycline (OXTC) and metabolite carbamazepine 10,11 epoxide (CBZ-E) on the brackish cyanobacterium Microcystis aeruginosa and the marine diatom Phaeodactylum tricornutum during chronic exposure experiments. A comprehensive approach was employed, incorporating various endpoints including oxidative stress, chlorophyll a fluorescence, detailed photoprotective and photosynthetic pigment profiles of target microorganisms to assess modes of action and identify the mixture effects of the selected substances.The observed alterations in pigment production affecting carotenoids synthesis in both selected species may be attributed to the differential impacts of these substances on the photosynthetic pathways and metabolic processes in the cyanobacterial and diatom cells. Changes in chlorophyll a fluorescence-specific parameters suggest impairment of the photosynthetic activity, particularly affecting the efficiency of photosystem II.The application of Concentration Addition (CA) and Independent Action (IA) mathematical models, complemented by the evaluation of Model Deviation Ratios (MDR), revealed predominantly antagonistic interactions within the studied mixtures. The findings of this study provide important insights into the effects of mixtures of organic micropollutants and their potential impact on environment including brackish and marine waters.

Inkjet-Printed Localized Surface Plasmon Resonance Subpixel Gas Sensor Array for Enhanced Identification and Visualization of Gas Spatial Distributions from Multiple Odor Sources

The visualization of the spatial distributions of gases from various sources is essential to understanding the composition, localization, and behavior of these gases. In this study, an inkjet-printed localized surface plasmon resonance (LSPR) subpixel gas sensor array was developed to visualize the spatial distributions of gases and to differentiate between acetic acid, geraniol, pentadecane, and cis-jasmone. The sensor array, which integrates gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), and fluorescent pigments, was positioned 3 cm above the gas source. Hyperspectral imaging was used to capture the LSPR spectra across the sensor array, and these spectra were then used to construct gas information matrices. Principal component analysis (PCA) enabled effective classification of the gases and localization of their sources based on observed spectral differences. Heat maps that visualized the gas concentrations were generated using the mean squared error (MSE) between the sensor responses and reference spectra. The array identified and visualized the four gas sources successfully, thus demonstrating its potential for gas localization and detection applications. The study highlights a straightforward, cost-effective approach to gas sensing and visualization, and in future work, we intend to refine the sensor fabrication process and enhance the detection of complex gas mixtures.

First Report of Robbsia andropogonis Causing Bacterial Blight of Danae racemosa (Poet’s Laurel) in a Virginia Ornamental Nursery

Danae racemosa (L.) Moench (Asparagaceae, Monocots) is a shade-tolerant, evergreen shrub native to Persia. On 02 July 2024, at an ornamental nursery in Hanover County, Virginia, 300 plants in 7.6 L containers were observed with blotchy, rust-colored, water-soaked lesions on the cladophylls and stems. Heavy bacterial streaming was observed from the lesions under the microscope, and sterilized tissue was cultured on King's B medium at 22 ± 2°C. After 72 hours, cream-colored colonies developed that were oxidase and gram negative and did not produce fluorescent pigments on King B medium. PCR amplification and sequencing of the partial 16S rRNA, gyrB, and rpoD genes from strain GS24-DSB16 were deposited into the NCBI Genbank database (PQ181184, PQ182786, PQ182787). Based on the morphological and molecular characteristics, the causal agent was identified as Robbsia andropogonis (Smith) Lopes-Santos et al. Koch’s postulates were fulfilled by wounding twenty cladophylls from each plant with a sterile needle, and 10 μl of an aqueous bacterial suspension was pipetted on each wound. R. andropogonis has a wide global distribution from a host range spanning >15 plant families, including maize, sorghum, sugarcane, citrus, coffee, and carnation. To the authors knowledge, this is the first report of the bacteria causing blight on D. racemosa, and the first host in Asparagaceae.

Seasonal biases in fluorescence-estimated chlorophyll-a derived from biogeochemical profiling floats

Marine phytoplankton biomass and chlorophyll-a concentration are often estimated from pigment fluorescence measurements, which have become routine despite known variability in the fluorescent response for a given amount of chlorophyll-a. Here, we present a near-global, monthly climatology of chlorophyll-a fluorescence measurements from profiling floats combined with ocean color satellite estimates of chlorophyll-a concentration to illuminate seasonal biases in the fluorescent response and expand upon previously observed regional patterns in this bias. Global biases span over an order of magnitude, and can vary seasonally by a factor of 10. An independent estimate of chlorophyll-a from light attenuation shows similar global patterns in the chlorophyll-fluorescence bias when compared to biases derived from satellite estimates. Without accounting for these biases, studies or models using fluorescence-estimated chlorophyll-a will inherit the seasonal and regional biases described here.

Tolerance and phytoremediation capacity of atrazine and S-metolachlor by two duckweeds.

The phytotoxicity and removal of atrazine and S-metolachlor in sterile duckweed systems were estimated in this study. Herbicides were added at environmentally relevant ranges: 0-400µg/L for atrazine or 0-200µg/L for S-metolachlor in systems with Spirodela polyrhiza or Lemna minor. Toxicity biomarkers, i.e., changes in plant biomass, surface area, chlorophyll fluorescence parameters, pigments, lipid peroxidation, protein concentration, and antioxidative enzyme activities in plants were estimated after 7days. S. polyrhiza (RGRbiomass-EC50 = 164.8µg/L) was more tolerant to atrazine than L. minor (RGRbiomass-EC50 = 101.0µg/L). Atrazine caused damage to photosystem II (ΦM), a reduction in electron transport between PSII and PSI (Φ'M), as well as disruption in energy distribution pathways (decrease in qPrel and increase in UQFrel), most prominently in L. minor. However, L. minor (RGRbiomass-EC50 = 128.9µg/L) was more tolerant to S-metolachlor than S. polyrhiza (RGRbiomass-EC50 = 15.5μg/L). The highest sensitivity of S. polyrhiza to S-metolachlor was attributed to a decrease in absorbed energy used in photochemistry (qPrel) and an increase in lipid peroxidation, indicating that S. polyrhiza plants were experiencing oxidative stress. Residual pesticide analysis in the water after seven days allowed us to conclude that plants were responsible for reducing up to 16.5% of atrazine and 28.7% of S-metolachlor in the duckweed system. S. polyrhiza showed higher atrazine phytoremediation capacity than L. minor. S. polyrhiza was more efficient at an environmentally relevant concentration of S-metolachlor (25μg/L) and L. minor at higher concentrations (200μg/L).

1, 3, 6, 8-pyrene sulfonic acid tetrasodium fluorescent pigment synthesis and security ink production

Colorants used in security inks are special pigments that radiate in the UV region or IR region. Obtained pigments can be from valuable rare earth elements or they can be organic based. Organic-based pigments are generally insoluble in water, which limits their use. For this purpose, an organic-based UV-radiating pigment was synthesized and made water-soluble by forming its salt. With the obtained salt-formed pigment, inkjet ink that can be used in counterfeiting was applied and its printability and resistance properties were determined. In this study, 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was synthesized and water-based inkjet inks with hydroxy ethyl cellulose binder were produced. The prepared inks were printed on the paper surface. The color and gloss of the prints obtained were measured both in the visible region and in the UV region. Its optical properties were detected by UV spectroscopy. Strength properties such as light fastness, nitro resistance, alkali resistance, acid resistance, rub resistance, drying time, adhesion and dry film weight of the prints were determined. As a result; Inkjet ink with 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was produced and it was concluded that it has good resistance properties.

A promising perspective to upgrade cotton dyeing performances when dyed with a red fluorescent pigment

This paper studied the dyeing with a fluorescent red pigment, and several dyeing performance problems were detected. This research aims to improve these performances, particularly those of dyeing fastness. Various surface treatments have been applied to bleached cotton fabrics to do this. Two commercial agents have been used, namely ST1 and ST2, which are essentially quaternary ammonium preparations with a cationic character. In addition, the dyeing process parameters have been studied, namely, the dyeing temperature, time and pH, to achieve the best conditions allowing acceptable dyeing performances with the fluorescent red pigment. Moreover, SEM images were taken for treated and untreated cotton fabrics, and no great morphological differences were detected. Finally, dyeing performances were evaluated based on the measurement of colourimetric coordinates, colour yield K/S and dyeing fastness properties. Very promising results have been found following a surface treatment with 8% of the agent ST1, a dyeing process of 30 inutes at 50°C for a pH of 8.

Toxicity of Moxifloxacin on the Growth, Photosynthesis, Antioxidant System, and Metabolism of Microcystis aeruginosa at Different Phosphorus Levels.

Moxifloxacin (MOX), a widely used novel antibiotic, may pose ecological risks at its actual environmental concentrations, as has been detected in aquatic systems. However, its ecotoxicity to aquatic organisms and regulatory mechanisms of phosphorus in eutrophic aqueous environments are still limited. This study aimed to analyze its physiological and biochemical parameters, including cellular growth, chlorophyll fluorescence, photosynthetic pigments, oxidative stress biomarkers, and metabolomics to elucidate the toxicity induced by environmental concentrations of MOX in Microcystis aeruginosa at different phosphorus levels. The results revealed that the EC50 values of MOX on M. aeruginosa at different phosphorus concentrations were 8.03, 7.84, and 6.91 μg/L, respectively, indicating MOX toxicity was exacerbated with increasing phosphorus levels. High phosphorus intensified the suppression of chlorophyll fluorescence and photosynthetic pigments, while activating the antioxidant enzyme, indicating severe peroxidation damage. Metabolomic analysis showed MOX induced different discriminating metabolites under different phosphorus levels, and perturbed more biological pathways at higher phosphorus concentrations, such as starch and sucrose metabolism, pyrimidine metabolism, and glycerolipid metabolism. This indicates that phosphorus plays an important role in regulating metabolism in M. aeruginosa exposed to MOX. The findings provide valuable information on the mechanisms involved in cyanobacteria responses to antibiotic stress, and offer a theoretical basis for accurately assessing antibiotic toxicity in eutrophic aqueous environments.

Exploring the Feasibility of Eu(TTA)3TPPO as Pigment for Fluorescent Paint

We outline the synthesis of rare earth hybrid organic β-diketonate Eu(TTA)3TPPO complex [Eu: Europium, TTA: Thenoyl Trifluoro Acetone, TPPO: Triphenylphosphine oxide] pigment to formulate luminous paints. Epoxy and urea formaldehyde resins were synthesized by catalytic homo polymerization and solution polymerization technique, respectively. The fluorescent pigment was synthesized at ambient temperature by solution technique, maintaining the stoichiometric ratio at pH 7. Nextly, fluorescent paint was developed on glass substrate with epoxy (E) and urea formaldehyde (UF) resins and toluene as solvent with thickness 0.1 mm, respectively. Photoluminescence (PL) spectra and photometric assessment of the complex were carried out to probe its photophysical parameters. The excitation spectra of the synthesized complex depicts a wide-ranging excitation peak at 466 nm with a wide shoulder at 538 nm, while emission spectra discloses an intense peak, recorded at 617 nm which portrays colour in the reddish-orange region of the visible spectrum. The paint compositions were checked for tack-free, hard dry, adhesion, water, salt, alkali and acid spray test to study their resistance against distinct surroundings. The painted panels also portrayed reddish orange emission at a unique wavelength of 617 nm. Amid all the paint compositions, the intensity of the painted panel with urea formaldehyde as a binder was found to be maximum, followed by the painted panel with epoxy as the binder. Photometric evaluation revealed reddish-orange emission from pure pigment as well as painted panels, which portrayed in the visible spectrum. This proposes a way to develop fluorescent paints that find applications in several areas such as flexible displays, glow-in-dark road paints, OLED devices, automotive rare lighting, fluorescent sensors, aircraft cabin and floor lighting, architectural and interior decorations and many more.

Exploring the Feasibility of Eu(TTA)<sub>3</sub>TPPO as Pigment for Fluorescent Paint

We outline the synthesis of rare earth hybrid organic β-diketonate Eu(TTA)3TPPO complex [Eu: Europium, TTA: Thenoyltrifluoroacetone, TPPO: Triphenylphosphine oxide] pigment to formulate luminous paints. Epoxy and urea-formaldehyde resins were synthesized by catalytic homo polymerization and solution polymerization technique, respectively. The fluorescent pigment was synthesized at ambient temperature by solution technique, maintaining the stoichiometric ratio at pH 7. Nextly, fluorescent paint was developed on glass substrate with epoxy (E) and urea-formaldehyde (UF) resins and toluene as solvent with thickness 0.1 mm, respectively. Photoluminescence spectra and photometric assessment of the complex were carried out to probe its photophysical parameters. The excitation spectra of the synthesized complex depict a wide-ranging excitation peak at 466 nm with a wide shoulder at 538 nm, while emission spectra disclosed an intense peak, recorded at 617 nm which portrays color in the reddish-orange region of the visible spectrum. The paint compositions were checked for tack-free, hard dry, adhesion, water, salt, alkali, and acid spray test to study their resistance against distinct surroundings. The painted panels also portrayed reddish-orange emission at a unique wavelength of 617 nm. Amid all the paint compositions, the intensity of the painted panel with UF as a binder was found to be maximum, followed by the painted panel with epoxy as the binder. Photometric evaluation revealed reddish-orange emission from pure pigment as well as painted panels, which are portrayed in the visible spectrum. This proposes a way to develop fluorescent paints that find applications in several areas such as flexible displays, glow-in-dark road paints, OLED devices, automotive rare lighting, fluorescent sensors, aircraft cabin and floor lighting, architectural and interior decorations, and many more. Received: 23 January 2024 | Revised: 1 April 2024 | Accepted: 27 May 2024 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available on request from the corresponding author upon reasonable request. Author Contribution Statement Vyankatesh Rajhans: Formal analysis, Investigation, Data curation, Writing – original draft, Visualization. N. Thejo Kalyani: Conceptualization, Methodology, Validation, Resources, Writing – review & editing, Supervision, Project administration. Akhilesh Ugale: Software, Writing – review & editing. S. J. Dhoble: Supervision, Project administration.

Temperature and soil moisture manipulation yields evidence of drought-induced pollen limitation in bee-pollinated squash.

Climate change alters environmental conditions in ways that directly and indirectly affect plants. Flowering plants, for example, modify reproductive allocation in response to heat and drought stress, and such changes can in turn affect pollinator visitation and, ultimately, plant reproduction. Although the individual effects of warming and drought on plant reproductive allocation are well known, these factors may interact to influence reproduction. Here, we conducted a fully crossed temperature by irrigation manipulation in squash (Cucurbita pepo) to test how temperature and soil moisture variation affect pollinator-mediated reproduction. To tease apart the direct and indirect effects of temperature and soil moisture, we compared hand-pollinated plants to bee-pollinated plants and restricted bee foraging (i.e., pollen transfer) to one experimental group per day. Temperature and soil-moisture limitation acted independently of one another: warming decreased flower size and increased pollen production, whereas the effects of soil-moisture limitation were uniformly inhibitory. While treatments did not change squash bee (Xenoglossa spp.) behavior, floral visitation by the honey bee (Apis mellifera) increased with temperature in male flowers and decreased with soil moisture in female flowers. Pollen deposition by bees was independent of plant soil moisture, yet reducing soil moisture increased pollen limitation. This result stemmed at least in part from the effects of soil-moisture limitation on pollen viability; seed set declined with increasing deposition of fluorescent pigment (a proxy for pollen) from plants experiencing decreased soil moisture. These findings suggest that the transfer of lower-quality pollen from plants experiencing soil-moisture limitation led to drought-induced pollen limitation. Similar effects may occur in a wide variety of flowering plant species as climate warming and drought increasingly impact animal-pollinated systems.

Naturally Bred Korean Silkworm Cocoon Showing Strong Green Fluorescence and Its Textile-Based Environmental Sensing Applications

ABSTRACT Mulberry silkworms have provided many valuable byproducts to humans for 5,000 years. However, numerous possibilities for their utilization still exist owing to the countless varieties of silkworms. Here, we report the application of Yeonnokjam silk (pistachio silk, PS), one of the characteristic silk varieties in Korea, as a smart fabric environmental sensor. Unlike the previously reported extrinsically modified silk varieties, this new silk textile emits fluorescence under external stimuli. PS cocoons were exposed to different concentrations of HCl vapors. Due to the large surface-to-volume ratio of the cocoon textile, a very low concentration (5 ppm) of HCl vapor can be detected by reading the decrease in the fluorescence intensity. At a lethal concentration (3000 ppm), an instantaneous fluorescence response is obtained. Additionally, the fluorescent pigment in PS can respond to temperature and can be extracted using ethanol, indicating that PS exhibits temperature and ethanol-sensing capabilities. The findings of this study prove that natural PS can be used in bio-optical applications.

Characterization of Erwinia amylovora causing Twig Blight of Loquat Tree in Loquat Growing Areas of Punjab and KPK, Pakistan

Twig blight of loquat (Eriobotrya japonica Lindl.), caused by the gram-negative enterobacterium Erwinia amylovora, is a major constraint to loquat production worldwide. Recent surveys in loquat-growing areas of Punjab and KPK, Pakistan—specifically in Chakwal (Kalar Kahar, Choa Saidan Shah), Rawalpindi (Taxila, Wah), Murree (Tret and Chattar), and Haripur (Haripur, Khanpur, and Sara i Saleh)—revealed that this disease is highly prevalent. Twig blight compromises the health and vigor of loquat trees, often leading to their death, which discourages farmers from cultivating loquat commercially. Consequently, the area under loquat cultivation and its production have both been declining. Despite the severity of the issue, no systematic studies had been conducted to address this problem until now. A survey was carried out over two consecutive years (2016 and 2017) in 10 loquat-growing locations in Punjab and KPK (three orchards per location). The incidence of twig blight was higher in 2017 compared to 2016. The highest incidence was recorded in Taxila, with 69.74% in 2016 and 78.39% in 2017, while the lowest was in Kalar Kahar (20.86%). The incidence in Kalar Kahar showed a slight increase of less than 1% from the previous year, likely due to effective control measures implemented to limit the spread of the disease. The pathogen E. amylovora was isolated from diseased samples. Out of 102 bacterial isolates, 92 strains were gram-negative, and 72 tested positive in various biochemical assays (Levan, lipase, KOVAC oxidase, glucose fermentation, catalase oxidase, growth at 39°C, production of fluorescent pigment, and pectolytic activity tests). Three highly virulent isolates were identified through pathogenicity tests and confirmed by biochemical and molecular indicators. Molecular tagging of two chromosomal genes (amsB [MN902191] and Pst-glms [MN915084]) and one plasmid gene (pAE29 [MN902192]) was performed, confirming the identity of the isolates as E. amylovora. This study represents the first report of E. amylovora infecting loquat in Pakistan.

Rarity of Pseudomonas agarici on Edible Mushrooms Associated with Susceptibility to Biological Competition.

Taxonomically diverse Pseudomonas species induce bacterial blotch of edible mushrooms around the world. Pseudomonas tolaasii, [P. gingeri], and P. agarici are dominant mycopathogenic pseudomonads in mushroom production farms. In this study, among 216 mycopathogenic bacterial strains isolated from edible mushrooms in Iran, 96 strains were identified as Pseudomonas spp., while only three strains were preliminarily identified as P. agarici. Multilocus sequence analysis showed that only one strain (FH2) authentically belonged to P. agarici, while the other two strains either belonged to [P. gingeri] or represented a unique phylogenetic clade. The three strains also differed from each other in phenotypic characteristics, for example, production of fluorescent pigment and the reaction to tolaasin produced by P. tolaasii. Pathogenicity assays under a controlled environment showed that the symptoms induced by authentic P. agarici were far less severe than those caused by the predominant species P. tolaasii. Furthermore, coinoculation of P. agarici with three bacterial pathogens that are prevalent in Iran on mushroom caps, that is, P. tolaasii, Ewingella americana, and Mycetocola sp., resulted in the development of combined symptoms representing characteristics of both pathogens. The antibiosis assay showed that tolaasin-producing strains of P. tolaasii could inhibit the growth of P. agarici, while tolaasin-negative strains of the same species were unable to do so. This led us to the hypothesis that the inhibitory effect of P. tolaasii on P. agarici is driven by tolaasin production in the former species. This inhibitory effect is also associated with the rarity of P. agarici in natural conditions.

Refining Gastrophysa atrocyanea (Coleoptera: Chrysomelidae) identification using UV marking in whole-plant assessment

The host plant quality is crucial for assessing the environmental safety of weed biological control agents, as they rely on the phenotypic characteristics of test plants in host specificity tests and for mass-rearing before field release. In this study, we explored the feasibility of using potted plants by applying ultraviolet (UV) fluorescent pigment to the elytra of the leaf beetle Gastrophysa atrocyanea. They were released separately on Rumex acetosa as the target weed and Buxus sinica var. insularis as a non-target plant in insect cages. UV marking reduced detection time by 2.7 times and increased the detection rates of female leaf beetles on the target weed compared to visible light, resulting in only 7.41% missing leaf beetles. Similarly, UV application reduced detection time by 2.3 times on the non-target plant, with no missing leaf beetles. Further, marking different sexes with UV pigments facilitated identification 4.8 times faster than visual light. The UV mark and recapture method exhibits promising potential in whole-plant testing, simplifying the identification of a potential biological control agent, G. atrocyanea, in insect cages under no-choice tests. Thus, UV marking enables the possibility of mass-rearing weed biological control agents and monitors the foraging behavior of phytophagous insects cost-effectively and non-disruptively in laboratory settings.

Foliar applied potassium nanoparticles (K-NPs) and potassium sulfate on growth, physiological, and phytochemical parameters in Melissa officinalis L. under salt stress.

Salinity stress significantly constrains agricultural productivity and vegetation decline worldwide, particularly in Iran. Potassium, the second most prevalent nutrient in plants, is well known to be essential for cell metabolism. Here, the effects of potassium fertilizer in two biogenic nanoparticles (K-NPs) and conventional (potassium sulfate) forms (0.1 mg/ml) on Melissa officinalis L. under salinity (0, 50, 100, and 150 mM) were investigated. The results demonstrated that stress markers (electrolyte leakage, malondialdehyde, and hydrogen peroxide) increased as salinity levels increased. Plant growth parameters (shoot and root length, fresh and dry weight of shoot and root) and physiological and photosynthetic parameters (stomatal conductance, relative water content, chlorophyll fluorescence, and photosynthetic pigments) were reduced in salinized plants. The highest reduction in fresh weight root, dry weight root, fresh weight shoot, dry weight shoot, root length, and shoot length was recorded under 150 mM NaCl by 30.2%, 51.6%, 30.5%, 24.7%, 26.4%, and 21%, respectively. In contrast, bulk potassium sulfate and K-NPs increased these parameters. Furthermore, K-NPs improved M. officinalis tolerance to NaCl toxicity by enhancing the content of osmolytes such as proline, soluble sugars, and antioxidant enzymes, improving antioxidant contents such as phenols, tannins, anthocyanins, and flavonoids; increasing total protein; and lowering stress markers in plant tissues. Given the results of the physiological, biochemical, and phytochemical parameters obtained from this study, it can be stated that K-NPs, in comparison to the conventional form of potassium fertilizer, exhibit a greater potential to mitigate damages caused by salinity stress in M. officinalis plants.

First report of Pseudomonas cichorii causing bacterial leaf blight of pocketbook plant (Calceolaria hybrida) in Taiwan.

Pocketbook plants (Calceolaria spp.) are flowering ornamentals often grown as potted plants (Poesch 1937). In December 2022, leaf blight symptoms were observed on 2-mo-old plants of C. hybrida F1 'Dainty'. The disease was found in a nursery in Ren'ai Township, Nantou, and about 20% of the plants exhibited symptoms. Symptomatic plants had brown or gray necrotic lesions of different sizes and shapes, mostly around leaf margins. Lower leaf wilting was also observed (Fig. S1, A and B). Three plants were sampled. Leaf lesions were surface-disinfected with 75% ethanol and cut into smaller pieces in 10 mM MgCl2. After observing bacterial streaming under a microscope, the bacteria were streaked onto nutrient agar (NA). Following 2 days at 28°C, a type of round, creamy white colony predominated on all the plates. Three strains (Calc-A, Calc-B, and Calc-C) were obtained, one from each plant. The strains produced fluorescent pigments on King's B medium and were tested Gram-negative. The strains were characterized with the LOPAT scheme (Schaad et al. 2001). They did not exhibit activities of pectic enzymes, arginine dihydrolase and levan sucrase, but produced oxidase and induced the hypersensitive response in tobacco. DNA was extracted from the strains for PCR amplification of the 16S rDNA with primer pair 27f/1492r as described by Lane (1991). The 16S rDNA sequences were compared with entries in the GenBank database. The sequences obtained (GenBank accession no. OR824302) matched that of Pseudomonas cichorii MAFF 301158 (accession no. AB724288; 1,403/1,403 bp) and were 99% identical to that of DSM 50259T (accession no. CP074349; 1,391/1,405 bp). The strains were also tested with the species-specific primers hrp1a and hrp2a (Cottyn et al. 2011). The amplicons were sequenced and a BLASTn search showed that the sequences (accession no. OR827305) shared the highest identity (99.3%) with that of P. cichorii strain 83-1 (accession no. DQ168848; 848/854 bp) and were 97.3% identical to the sequence of DSM 50259T (accession no. CP074349; 831/854 bp). Calc-A was selected as a representative strain and deposited in the Bioresource Collection and Research Center, Taiwan (reference no. BCRC 81432). Koch's postulates were fulfilled by spray-inoculating a suspension of Calc-A on three 2-mo-old C. hybrida F1 'Dainty' plants. The inoculum was prepared by suspending NA-grown cells in 10 mM MgCl2 including 0.02% Silwet L-77 (OD600 = 0.3; 1.5 x 108 CFU/ml). For the controls, three plants were sprayed with bacteria-free solution. The plants were bagged throughout the experiment and kept in a growth chamber (14/10 h light/dark; 26/24°C day/night). Leaf blight and wilting symptoms developed on all leaves of the inoculated plants after 30 h, but not the controls (Fig. S1, C and D). The pathogen was reisolated from the treatment group, and colony PCR with hrp1a/hrp2a showed that the reisolated strain shared the same sequence with Calc-A to Calc-C. Repeating the inoculation assay produced consistent results. This is the first report of P. cichorii affecting Calceolaria in Taiwan. The bacterium has been reported infecting diverse crops in Taiwan, such as tomato and lettuce (Tsai et al. 2014). Expanding the understanding of the pathogen's potential hosts could help prevent its spread across important crops.