UV-B Damage Research Articles

A study on the anti-skin tumor and anti-UVB damage effects of Gastrodia elata Bl. Products transformed by Armillaria mellea

ABSTRACT Skin cancer is a malignant tumour that can spread in the skin and is a serious threat to human health. Excessive ultraviolet radiation is one of the most common factors that leads to skin cancer. The purpose of this study was to evaluate the anti-skin tumour and anti-UVB damage effects of Armillaria mellea (Vahl) P. Kumm transformed Gastrodia elata Bl products (ATGP). Gastrodia elata Blume f.glauca S. Chows from Changbai Mountain and 4 Armillaria mellea (Vahl) P. Kumm strains were used as experimental materials. First, the optimum fungal strains of Armillaria mellea used to transform gastrodin were screened. Then, the MTT assay and scratch test proved that ATGP had anti-B16 melanoma cell activity in vitro. Furthermore, the anti-UVB damage effect of ATGP was proven by a UVB damage mouse skin model and HaCat photoaging model, and its mechanism was preliminarily discussed.

δ-Catenin Requirement in Keratinocyte Proliferation and DNA Repair Identifies a Therapeutic Target for Photoaging

Skin photoaging is a complicated pathological process and is mainly due to UV irradiation, especially UVB irradiation. Damage induction by UVB is a complex process, involving intricate molecular mechanisms. The formation of bulky photoproducts in the DNA globally affects transcription and splicing and results in the dysfunction of keratinocytes. In this study, we show that δ-catenin is predominantly distributed in keratinocytes of the skin epidermis and functionally accelerates cell proliferation and DNA repair. Exvivo protein profiling reveals that δ-catenin upregulates the phosphorylation of RSK2Ser-227 by enhancing the interaction between PDK1 and RSK2 and thereby induces the nuclear accumulation of YB1 to promote proliferation and DNA repair. Moreover, δ-catenin overexpression induces invivo keratinocyte proliferation and DNA repair in UVB-irradiated mouse skin. Notably, acidic fibroblast GF/FGFR1 is identified as one of the key upstream signalings of δ-catenin by inducing δ-catenin stabilization. The involvement of δ-catenin in keratinocyte proliferation and DNA repair may suggest δ-catenin as a target for the treatment of UVB damage.

Optional strategies for low-risk and non-risk applications of fungal pesticides to avoid solar ultraviolet damage.

Solar ultraviolet (UV) irradiation is harmful to formulated conidia as active ingredients of fungal pesticides and hence restrains their field application in sunny days of summer, a season requiring frequent pest controls. This conflict makes it necessary to explore optimal strategies for the application of fungal pesticides to suppress pest populations but avoid solar UV damage during summer. The conidia of Beauveria bassiana, a wide-spectrum fungal pesticide, were tolerable to UVB (major solar UV wavelengths) damage of ≤0.5J cm-2 . The damage of this upper limit caused a loss of conidial viability and infectivity if not photoreactivated by light exposure after irradiation. Intriguingly, the light exposure resulted in a high photoreactivation rate of UVB-inactivated conidia and an insignificant or marginal difference in insecticidal activity between normal conidia and those photoreactivated. Modeling analysis of solar UVB intensity recorded hourly over the daylight of five sunny summer days from 5:00 am to 7:00 pm at 30° 17'57''N and 120°5'7''E revealed a variation of daily accumulated UVB dose from 2.07 to 2.78 J cm-2 , which was far beyond the upper limit. A more tolerable dose of ~0.2J cm-2 appeared between 3:00 pm and 5:00 pm, and no harmful dose accumulated between 5:00 pm and 7:00 pm. Fungal UVB tolerance, fungal photoreactivation capability and the daily accumulation pattern of solar UV irradiation are based to propose an optional strategy for low-risk or non-risk application of fungal pesticides after 3:00 or 5:00 pm during summer. © 2022 Society of Chemical Industry.

Molecular characterization, antiviral activity, and UV-B damage responses of Caspase-9 from Amphiprion clarkii

Apoptosis plays a vital role in maintaining cellular homeostasis in multicellular organisms. Caspase-9 (casp-9) is one of the major initiator caspases that induces apoptosis by activating downstream intrinsic apoptosis pathway genes. Here, we isolated the cDNA sequence (1992 bp) of caspase-9 from Amphiprion clarkii (Accasp-9) that consists of a 1305 bp coding region and encodes a 434 aa protein. In silico analysis showed that Accasp-9 has a theoretical isoelectric point of 5.81 and a molecular weight of 48.45 kDa. Multiple sequence alignment revealed that the CARD domain is located at the N-terminus, whereas the large P-20 and small P-10 domains are located at the C-terminus. Moreover, a highly conserved pentapeptide active site (296QACGG301), as well as histidine and cysteine active sites, are also retained at the C-terminus. In phylogenetic analysis, Accasp-9 formed a clade with casp-9 from different species, distinct from other caspases. Accasp-9 was highly expressed in the gill and intestine compared with other tissues analyzed in healthy A. clarkii. Accasp-9 expression was significantly elevated in the blood after stimulation with Vibrio harveyi and polyinosinic:polycytidylic acid (poly I:C; 12–48 h), but not with lipopolysaccharide. The nucleoprotein expression of the viral hemorrhagic septicemia virus was significantly reduced in Accasp-9 overexpressed fathead minnow (FHM) cells compared with that in the control. In addition, other in vitro assays revealed that cell apoptosis was significantly elevated in poly I:C and UV-B-treated Accasp-9 transfected FHM cells. However, H248P or C298S mutated Accasp-9 significantly reduced apoptosis in UV-B irradiated cells. Collectively, our results show that Accasp-9 might play a defensive role against invading pathogens and UV-B radiation and H248 and C298 active residues are significantly involved in apoptosis in teleosts.

Effect of Apple (Malus domestica) Stem Cells on UVB-Induced Damage Skin with Anti-Inflammatory Properties: An In Vivo Study

Objective. Apple (Malusdomesticus) stem cells have beneficial effects in preventing photodamages caused by UVB responsible for inflammation in different stages of various skin disorders. This study aimed to investigate Apple stem cells’ anti-inflammatory and repairing effects on UVB-induced rat dorsal skin damage via microscopic and macroscopic analyses. Materials and Methods. Therapeutic effects of the apple stem cells (ASCs) extract were evaluated after UVB irradiation with macroscopic and microscopic studies, including pathological analysis, inflammatory cytokines measuring, and biometric studies containing investigation of thickness, density, erythema, melanin, sebum, and moisture content of epidermis and dermis layers in rat models. After biometric studies, skin samples were taken for histopathologic and biochemical analyses. Results. ASC extract could attenuate infiltration of inflammatory cells caused by UVB and ameliorate collagen regulation of the photodamaged skin. In addition, improved skin biometrics was considerable, such as reducing thickened epidermal and dermal layers compared to other rat groups. Furthermore, moisture content enhancement of the skin showed clinical advantages in treating damages and inflammation. Furthermore, TNF-α expression was downregulated after ASC application. ASC extract could treat UVB damages and indicate anti-inflammatory effects in animal models. Conclusion. The ASCs can be an appropriate candidate for treating inflammation and damages induced by UVB in clinical studies.

Study from microcosms and mesocosms reveals Escherichia coli removal in high rate algae ponds during domestic wastewater treatment is primarily caused by dark decay.

While high rate algal ponds (HRAPs) can provide efficient pathogen removal from wastewater, the mechanisms involved remain unclear. To address this knowledge gap, the mechanisms potentially causing Escherichia coli (E. coli) removal during microalgae-based wastewater treatment were successively assessed using laboratory microcosms designed to isolate known mechanisms, and bench scale assays performed in real HRAP broth. During laboratory assays, E. coli decay was only significantly increased by alkaline pH (above temperature-dependent thresholds) due to pH induced toxicity, and direct sunlight exposure via UV-B damage and/or endogenous photo-oxidation. Bench assays confirmed alkaline pH toxicity caused significant decay but sunlight-mediated decay was not significant, likely due to light attenuation in the HRAP broth. Bench assays also evidenced the existence of uncharacterized 'dark' decay mechanism(s) not observed in laboratory microcosms. To numerically evaluate the contribution of each mechanism and the uncertainty associated, E. coli decay was modelled assuming dark decay, alkaline pH induced toxicity, and direct sunlight-mediated decay were independent mechanisms. The simulations confirmed E. coli decay was mainly caused by dark decay during bench assays (48.2-89.5% estimated contribution to overall decay at the 95% confidence level), followed by alkaline-pH induced toxicity (8.3-46.5%), and sunlight-mediated decay (0.0-21.9%).

Anticancer Activities of Marine-Derived Phenolic Compounds and Their Derivatives.

Since the middle of the last century, marine organisms have been identified as producers of chemically and biologically diverse secondary metabolites which have exerted various biological activities including anticancer, anti-inflammatory, antioxidant, antimicrobial, antifouling and others. This review primarily focuses on the marine phenolic compounds and their derivatives with potent anticancer activity, isolated and/or modified in the last decade. Reports on the elucidation of their structures as well as biosynthetic studies and total synthesis are also covered. Presented phenolic compounds inhibited cancer cells proliferation or migration, at sub-micromolar or nanomolar concentrations (lamellarins D (37), M (38), K (39), aspergiolide B (41), fradimycin B (62), makulavamine J (66), mayamycin (69), N-acetyl-N-demethylmayamycin (70) or norhierridin B (75)). In addition, they exhibited anticancer properties by a diverse biological mechanism including induction of apoptosis or inhibition of cell migration and invasive potential. Finally, phlorotannins 1–7 and bromophenols 12–29 represent the most researched phenolic compounds, of which the former are recognized as protective agents against UVB or gamma radiation-induced skin damages. Finally, phenolic metabolites were assorted into six main classes: phlorotannins, bromophenols, flavonoids, coumarins, terpenophenolics, quinones and hydroquinones. The derivatives that could not be attributed to any of the above-mentioned classes were grouped in a separate class named miscellaneous compounds.

Effect of nano-selenium loaded with lycium barbarum polysaccharide on the proliferation of lens epithelial cells after UVB damage in vitro.

To investigate the effect of nano-selenium loaded with different concentrations of lycium barbarum polysaccharide (LBP-SeNPs) on the proliferation of human lens epithelial cells (HLECs) from UV irradiation. LBP-SeNPs were prepared and their particle size was detected. HLECs (SRA01/04) were irradiated with UVB for different time (0, 10, 20, 30, 40, 50, 60min) to construct a damaged model, the survival rate of cells was determined by methylthiazol tetrazolium (MTT) assay. The 4',6-Diamidine-2'-phenylindole dihydrochloride (DAPI) staining was used to observe the status of cell nucleus and drug entering cytoplasm through cell membrane in SRA01/04 cells after adding LBP-SENPS loaded with coumarin fluorescence agent 24h under fluorescence microscope. SRA01/04 normal and UVB-damaged cells were treated with different amounts of LBP-SeNPs at different concentrations, cells proliferation were observed. The particle size of LBP-SeNPs was stable in the range of 150-200 nm. The survival rate changes with time after UVB irradiation were statistically significant. The 10min of UVB exposure as the time was chosen to construct the cell damage model. With DAPI staining, LBP-SeNPs were observed to enter the cytoplasm through the cell membrane under fluorescence inverted microscope. Cytotoxicity of SRA01/04 at different concentrations of LBP-SeNPs were measured. Cell survival rate was statistically different compared with the control group. The higher the loading concentration of LBP in nano-Se drugs was, the higher the cell proliferation rate was (P<0.05). The lower the concentration of LBP-SeNPs, the higher the cell proliferation rate, showing a negative growth trend (P<0.05). The group with the highest average cell proliferation rate was 0.5 µmol/L 2.0 mg/mL LBP-SeNPs (128.80%). When the 2.0 mg/mL LBP-SeNPs group was selected for cell photography, the cell density was higher at 0.5 µmol/L. With the increase of concentration, SRA01/04 cells appeared more cytoplasm dehydration, cell shrinkage and apoptotic bodies, and cell density decreased. LBP-SeNPs has moderate particle size and good stability. LBP-SeNPs can protect HLECs (SRA01/04) from UVB-induced damage, and the cell proliferation rate is further increased with increasing the amount of loaded LBP and decreasing nano-selenium concentration.

A novel glyceroglycolipid from brown algae Ishige okamurae improve photoaging and counteract inflammation in UVB-induced HaCaT cells

BackgroundExcessive exposure to Ultraviolet (UV) rays can cause premature skin aging. Ishigoside (IGS) is a new glyceroglycolipid compound isolated from brown algal Ishige okamurae, However, whether it can protect the skin from (Ultraviolet-B) UVB damage has not been illuminated. MethodsThe in vitro anti-photoaging effect of IGS was conducted in UVB-induced HaCaT. The HaCaT cells were divided into the following five groups: (1) cells didn't suffer from UVB irradiation or IGS treatment. (2–5) Cells were treated with various concentrations of IGS (0, 10, 50, and 100 μM) and irradiated by 40 mJ/cm2 UVB. The Matrix metalloproteinase (MMP) of photoaging process was determined by ELISA kits and the latent interaction between IGS and MMP was further performed by molecular docking. The crucial signaling pathway proteins involved in the collagen synthesis and degradation were subsequently evaluated by Western blotting, immunofluorescence and EMSA. ResultsIGS effectively suppresses the high expressions and secretions of matrix metalloproteinases (MMPs) and photo-inflammation by blocking MAPKs, AP-1 and NF-κB. Meanwhile, increasing antioxidant enzyme expression. Molecular docking results suggest that inhibition of IGS on MMPs may be attributed to its hydrogen supply and hydrophobic capacity. In addition, IGS enhanced procollagen production by upregulating the TGF-β/Smad pathways. ConclusionsIGS exhibited anti-photoaging activity in UVB-damage HaCaT. These effects might be a contribution by its suppression of MMPs expression via MAPKs, AP-1 and NF-κB pathway and have anti-oxidative and anti-inflammatory effects. Therefore, IGS has the great potential to become skin-care products or functional foods for preventing skin photoaging.

Cytoprotective Effects of Water Soluble Dihydropyrimidinthione Derivative Against UV-B Induced Human Corneal Epithelial Cell Photodamage.

Excessive UV-B exposure is well known to be a risk factor for corneal phototoxicity including direct DNA damage and disturbances in the antioxidant balance. Here, we showed a successful synthesis of a water-soluble and biocompatible small molecule DHPM 1 with dihydropyrimidinthione skeleton, which could effectively protect human corneal epithelial (HCE-2) cells from UV-B damage. In separate experiments, DHPM 1 absorbed UV-B rays and exhibited scavenging activity against intracellular ROS induced by UV-B radiation, thereby reducing the levels of DNA fragmentation. Additionally, UV-B exposure increased the expression of cleaved caspase-3, as well as the ratio of Bax/Bcl-2 at protein levels, while pretreatment with DHPM 1 significantly reversed these changes. To the best of our knowledge, this is the first report of a study based on dihydropyrimidinthione derivatives to develop a promising eye drops, which may well find extensive applications in UV-B caused corneal damage.

Metabolomics study of fibroblasts damaged by UVB and BaP

We have recently shown that both UVB and BaP can induce the production of ROS, apoptosis and even cancer. However, the differences in the metabolic profiles of skin damaged by UVB, BaP or UVB combined with BaP have not been studied. Therefore, we examined the metabolic changes in the human foreskin fibroblast injured by UVB or BaP or the combination of the two, using ultra performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (qTOF-MS). 24 metabolites were altered in the UVB damage group, 25 in the BaP damage group, and 33 in the UVB combined with BaP group. These alterations indicated that the metabolic mechanisms of HFF-1 cells treated with UVB or BaP are related to multiple main metabolites including glycerophosphocholine (PC), lactosylceramide (LacCer), guanidinosuccinic acid (GSA), glutathione(GSH), and lysophosphatidylcholine (LysoPC) and the main mechanisms involved glycerophospholipid and glutathione metabolism. Thus, our report provided useful insight into the underlying mechanisms of UVB and BaP damage to skin cells.

EDNA-Mediated Cutaneous Protection Against UVB Damage Conferred by Staphylococcal Epidermal Colonization.

The human skin is a lush microbial habitat which is occupied by a wide array of microorganisms. Among the most common inhabitants are Staphylococcus spp., namely Staphylococcus epidermidis and, in ≈20% of healthy individuals, Staphylococcus aureus. Both bacteria have been associated with cutaneous maladies, where they mostly arrange in a biofilm, thus achieving improved surface adhesion and stability. Moreover, our skin is constantly exposed to numerous oxidative environmental stressors, such as UV-irradiation. Thus, skin cells are equipped with an important antioxidant defense mechanism, the Nrf2–Keap1 pathway. In this work, we aimed to explore the morphology of S. aureus and S. epidermidis as they adhered to healthy human skin and characterize their matrix composition. Furthermore, we hypothesized that the localization of both types of bacteria on a healthy skin surface may provide protective effects against oxidative stressors, such as UV-irradiation. Our results indicate for the first time that S. aureus and S. epidermidis assume a biofilm-like morphology as they adhere to ex vivo healthy human skin and that the cultures’ extracellular matrix (ECM) is composed of extracellular polysaccharides (EPS) and extracellular DNA (eDNA). Both bacterial cultures, as well as isolated S. aureus biofilm eDNA, conferred cutaneous protection against UVB-induced apoptosis. This work emphasized the importance of skin microbiota representatives in the maintenance of a healthy cutaneous redox balance by activating the skin’s natural defense mechanism.

Mitophagy-A New Player in UV-B Damage Recovery in Plants.

Mitophagy-A New Player in UV-B Damage Recovery in Plants.

Cloves Regulate Na+-K+-ATPase to Exert Antioxidant Effect and Inhibit UVB Light-Induced Skin Damage in Mice.

The purpose of this study was to observe the effect of cloves (Syzygium aromaticum (L.) Merr. & L.M. Perry) on the mouse skin using a UVB-induced skin injury mouse model. The serum, liver, and skin indexes of mice were determined by kits, H&E tissue staining, and qPCR assay. The compound composition of cloves was determined by HPLC. The results showed that cloves increased the activity of Na+-K+-ATPase in the skin and then maintained the sodium and potassium pump in the damaged skin muscle membrane. Cloves alleviated the oxidative stress injury induced by UVB irradiation by normalizing the related oxidative stress indexes (T-SOD, CAT, AGEs, and H2O2) in serum and skin. Inhibition of the proinflammatory cytokines TNF-α, IL-1β, and IL-6 and increased activation of anti-inflammatory cytokines IL-4 and IL-10 occurred after treatment with cloves, which ultimately reduced the inflammatory damage to the body. Further results showed that cloves upregulate SOD1, SOD2, CAT, GSH, IL-10, IκB-α, AMPK, SIRT1, LKB1, PGC-1α, APPL1, and FoxO1 and downregulate NF-κB p65, TNF-α, IL-6, and mTOR mRNA expression in the skin tissues of UVB-damaged mice. The results of composition analysis showed that the five most abundant compounds in cloves are rutin, isoquercitrin, ferulic acid, dihydroquercetin, and quercitrin. Cloves regulate the skin sarcomembrane Na+-K+-ATPase through these five compounds, and because they regulate the oxidation, inflammation, and ATP energy consumption of the body, they subsequently protect the skin from UVB damage.

Preparation and optimization of silibinin-loaded chitosan–fucoidan hydrogel: an in vivo evaluation of skin protection against UVB

Purpose The objective of this study was to develop silibinin-loaded hydrogel for skin protection against UVB damage. Method Physical grafting was used to prepare hydrogel based on chitosan–fucoidan. Then, hydrogel properties, such as swelling, drug release rates, morphology, and structure, were evaluated to determine the optimum hydrogel for in vivo studies. In in vivo experiments, the silibinin permeability parameters were investigated through normal and UV-irradiated skin, anti-inflammatory property, and antioxidant effects after application of optimum hydrogel. Results The silibinin completely dispersed in the hydrogel, and FT-IR results showed that silibinin reacted with the chitosan and fucoidan and demonstrated a slow release pattern. The 50% and less than 70% of the drug-loaded on hydrogel were passed through normal and irradiated skin after 48 h, respectively. In vivo studies showed the effectiveness of optimized hydrogel in preventing the production of oxidative species and H2O2 after UVB radiation. Histological studies have shown that silibinin-loaded optimized hydrogel can prevent the hyperkeratosis, acanthosis, and infiltration of neutrophils into the dermis by UVB. Conclusion Optimized hydrogel effectively reduced the inflammation mediators interleukin-22 and TNF-α, which signify tissue destruction. Therefore, silibinin-loaded hydrogel can be introduced as an effective sun-protective product.

Non-invasive evaluation of elasticity of skin with the processing of ultrasound images during ultraviolet radiation: An animal photoaging model.

The aim of this study was to provide a non-invasive imaging method to evaluate the physical and mechanical parameters as a novelty method during skin photoaging. In order to evaluate the process of skin damage, 25 mice (C57BL6) were exposed to UVB radiation (0.03mW/cm2 ), 5 times a week for 5weeks. The thickness of the epidermal and dermal layers was measured weekly from the ultrasound images (40MHz). The elastic parameters of the skin were estimated from the processing of the sequential ultrasound images with the motion detection algorithm during the injury generation process. The thickening, Young modulus, and shear modulus of the dermal and epidermal layers during the UVB damage process significantly increased during the 5-week study period (P<.05). In addition, the percentage of changes in the thickness of the epidermal layer (0.22±0.01mm in day 0 to 0.37±0.02mm in day 35) and dermal layer (0.57±0.05mm in day 0 to 0.90±0.08mm in day 35) increased by 68% and 57%, respectively. Furthermore, Young modulus (154.41±8.8kPa) was 11 times more than that of non-irradiated skin (14.90±2.2kPa) and the shear modulus (2.33±0.04kPa) was 2.2 times more than non-irradiated skin (1.06±0.04kPa). With processing the sequential ultrasound images and extracting the thickening, the elasticity of the skin layers can detect skin lesions by UVB radiation.

Spiny mice (Acomys) exhibit attenuated hallmarks of aging and rapid cell turnover after UV exposure in the skin epidermis.

The study of long-lived and regenerative animal models has revealed diverse protective responses to stressors such as aging and tissue injury. Spiny mice (Acomys) are a unique mammalian model of skin wound regeneration, but their response to other types of physiological skin damage has not been investigated. In this study, we examine how spiny mouse skin responds to acute UVB damage or chronological aging compared to non-regenerative C57Bl/6 mice (M. musculus). We find that, compared to M. musculus, the skin epidermis in A. cahirinus experiences a similar UVB-induced increase in basal cell proliferation but exhibits increased epidermal turnover. Notably, A. cahirinus uniquely form a suprabasal layer co-expressing Keratin 14 and Keratin 10 after UVB exposure concomitant with reduced epidermal inflammatory signaling and reduced markers of DNA damage. In the context of aging, old M. musculus animals exhibit typical hallmarks including epidermal thinning, increased inflammatory signaling and senescence. However, these age-related changes are absent in old A. cahirinus skin. Overall, we find that A. cahirinus have evolved novel responses to skin damage that reveals new aspects of its regenerative phenotype.

Detrimental Effects of UVB on Retinal Pigment Epithelial Cells and Its Role in Age-Related Macular Degeneration.

Retinal pigment epithelial (RPE) cells are an essential part of the human eye because they not only mediate and control the transfer of fluids and solutes but also protect the retina against photooxidative damage and renew photoreceptor cells through phagocytosis. However, their function necessitates cumulative exposure to the sun resulting in UV damage, which may lead to the development of age-related macular degeneration (AMD). Several studies have shown that UVB induces direct DNA damage and oxidative stress in RPE cells by increasing ROS and dysregulating endogenous antioxidants. Activation of different signaling pathways connected to inflammation, cell cycle arrest, and intrinsic apoptosis was reported as well. Besides that, essential functions like phagocytosis, osmoregulation, and water permeability of RPE cells were also affected. Although the melanin within RPE cells can act as a photoprotectant, this photoprotection decreases with age. Nevertheless, the changes in lens epithelium-derived growth factor (LEDGF) and autophagic activity or application of bioactive compounds from natural products can reverse the detrimental effect of UVB. Additionally, in vivo studies on the whole retina demonstrated that UVB irradiation induces gene and protein level dysregulation, indicating cellular stress and aberrations in the chromosome level. Morphological changes like retinal depigmentation and drusen formation were noted as well which is similar to the etiology of AMD, suggesting the connection of UVB damage with AMD. Therefore, future studies, which include mechanism studies via in vitro or in vivo and other potential bioactive compounds, should be pursued for a better understanding of the involvement of UVB in AMD.

Solar UVB-inducible ethylene alone induced isoflavonoids in pods of field-grown soybean, an important defense against stink bugs

Solar UV-B radiation enhances constitutive and inducible plant defenses against herbivore insects. Although inducible defenses in leaves damaged by lepidotperan larvae and other chewing insects are well known, almost nothing is noted for the response of reproductive organs in response to stink bug attack. Here we measured the induction of phytohormones and flavonoids in undamaged and damaged pods by stink bug (Piezodorus guildinii) adults. We compared two different soybean cultivars grown under two levels of solar UV-B radiation. Stink bug and mechanical damage increased isoflavonoid content in pods of both cultivars and solar UV-B tended to enhance induction, without affecting isoflavonoids in undamaged pods. While pod flavonols levels did not change by stink bug attack, mechanical damage or to solar UV-B, herbivory and mechanical damage increased seed isoflavonoids, and solar UV-B did not affect seed isoflavonoid content. Although stink bug damage induced ethylene (ET) from pods of cv. Charata, herbivory did not affect ET emission in cv. Williams. Solar UV-B radiation increased ET emission in mechanically damaged pods of cv. Charata, but did not affect other phytohormones. Both mechanical and stink bug damage induced jasmonates in seed of both cultivars. Application of the ET precursor ACC alone, but not MeJA or SA increased isoflavonoid content in pods of cv. Charata. Our field experiments suggest that herbivory- and solar UV-B radiation-induced ET by itself is sufficient to increase the level of defensive isoflavonoids in pods against stink bugs.

Photosynthetic performance of five cool-season turfgrasses under UV-B exposure

Turfgrasses are monocotyledonous plants from the family Poaceae. They are widely used in green spaces and are considered one of the most economically important horticultural crops in the world. Turfgrass quality is affected by several environmental factors including light, which is involved in the quality decline of transplanted sod. Ultraviolet-B (UV–B) is an important regulator of plant growth and development. Plants growing and/or stored in protected systems, such as in sod production, may be more vulnerable to UV-B damage than those growing in the field due to acclimation. Few studies on the effects of UV-B on turfgrass physiology have been published. Therefore, the aim of this study was to evaluate the influence of UV-B irradiation on the photosynthetic performance of five cool-season turfgrasses, namely Agrostis stolonifera L., Festuca arundinacea Schreb., Poa supina Schrad., Poa pratensis L. and Lolium perenne L. Turfgrasses were exposed to 18.25 kJ m−2 d−1 biologically effective UV-B in growth chambers under controlled conditions. Measurements included photosynthetic pigments, chlorophyll fluorescence and gas exchanges monitored for 16 d-UV-B treatment and after recovery. Content of pigments decreased with UV-B exposure with significant differences among the species. UV-B also affected the photosystem II (PSII) efficiency depending on the exposure period and species. Similarly, gas exchange parameters showed different effects among species after UV-B exposure compromising the assimilation of CO2. Multivariate analysis highlighted three main clusters of species confirming their different UV-B tolerance and ability to restore PSII photochemistry after recovery, from which Festuca arundinacea resulted to be the most tolerant.