UV-B Radiation Stress Research Articles

Metabolomic Analysis of Elymus sibiricus Exposed to UV-B Radiation Stress

Plants cultivated on the Qinghai-Tibet Plateau (QTP) are exposed to high ultraviolet radiation intensities, so they require effective mechanisms to adapt to these stress conditions. UV-B radiation is an abiotic stress factor that affects plant growth, development, and environmental adaptation. Elymus sibiricus is a common species in the alpine meadows of the QTP, with high-stress resistance, large biomass, and high nutritional value. This species plays an important role in establishing artificial grasslands and improving degraded grasslands. In this study, UV-B radiation-tolerant and UV-B radiation-sensitive E. sibiricus genotypes were subjected to simulated short-term (5 days, 10 days) and long-term (15 days, 20 days) UV-B radiation stress and the metabolite profiles evaluated to explore the mechanism underlying UV-B radiation resistance in E. sibiricus. A total of 699 metabolites were identified, including 11 primary metabolites such as lipids and lipid-like molecules, phenylpropanoids and polyketides, organic acids and their derivatives, and organic oxygen compounds. Principal component analysis distinctly clustered the samples according to the cultivar, indicating that the two genotypes exhibit distinct response mechanisms to UV-B radiation stress. The results showed that 14 metabolites, including linoleic acid, LPC 18:2, xanthosine, and 23 metabolites, including 2-one heptamethoxyflavone, glycyrrhizin, and caffeic acid were differentially expressed under short-term and long-term UV-B radiation stress, respectively. Therefore, these compounds are potential biomarkers for evaluating E. sibiricus response to UV-B radiation stress. Allantoin specific and consistent expression was up-regulated in the UV-B radiation-tolerant genotype, thereby it can be used to identify varieties resistant to UV-B radiation. Different metabolic profiles and UV-B radiation response mechanisms were observed between the UV-B radiation-tolerant and UV-B radiation-sensitive E. sibiricus genotypes. A model for the metabolic pathways and metabolic profiles was constructed for the two genotypes. This metabolomic study on the E. sibiricus response to UV-B radiation stress provides a reference for the breeding of new UV-B radiation-tolerant E. sibiricus cultivars.

Mitigation of UV-B Radiation Stress in Tobacco Pollen by Expression of the Tardigrade Damage Suppressor Protein (Dsup).

Pollen, the male gametophyte of seed plants, is extremely sensitive to UV light, which may prevent fertilization. As a result, strategies to improve plant resistance to solar ultraviolet (UV) radiation are required. The tardigrade damage suppressor protein (Dsup) is a putative DNA-binding protein that enables tardigrades to tolerate harsh environmental conditions, including UV radiation, and was therefore considered as a candidate for reducing the effects of UV exposure on pollen. Tobacco pollen was genetically engineered to express Dsup and then exposed to UV-B radiation to determine the effectiveness of the protein in increasing pollen resistance. To establish the preventive role of Dsup against UV-B stress, we carried out extensive investigations into pollen viability, germination rate, pollen tube length, male germ unit position, callose plug development, marker protein content, and antioxidant capacity. The results indicated that UV-B stress has a significant negative impact on both pollen grain and pollen tube growth. However, Dsup expression increased the antioxidant levels and reversed some of the UV-B-induced changes to pollen, restoring the proper distance between the tip and the last callose plug formed, as well as pollen tube length, tubulin, and HSP70 levels. Therefore, the expression of heterologous Dsup in pollen may provide the plant male gametophyte with enhanced responses to UV-B stress and protection against harmful environmental radiation.

Physio-biochemical and transcriptomics analyses reveal molecular mechanisms of enhanced UV-B stress tolerance in rice induced by titanium dioxide nanoparticles

ABSTRACT Rice (Oryza sativa L.) stands out as the world's most vital staple food crop, yet is susceptible to UV-B radiation stress. This study investigates the physiological and transcriptome responses in rice exposed to titanium dioxide nanoparticles (TiO2 NPs) under UV-B radiation. Results demonstrate that TiO2 NPs, applied alone (TN) or in combination with UV-B stress (UV+TN), significantly enhance rice plant growth and physiological parameters. Reactive oxygen species (ROS) levels, elevated under UV-B stress, are significantly reduced by TN and UV+TN treatments, thereby regulating antioxidants particularly involved in ascorbate-glutathione pathway. Transcriptomics analysis of identified DEGs in UV+TN, utilizing KEGG pathway analysis, reveals significant enrichment in various pathways. These pathways include glutathione metabolism, pyruvate metabolism, starch and sucrose metabolism, regulation of basal transcription factors, plant hormonal signal transduction pathways, cellular processes associated with energy, and the MAPK signaling pathway. Overall, TiO2 NPs application modulates diverse biological and metabolic pathways, enhancing UV-B stress tolerance in rice.

Potential of UV-B radiation in drought stress resilience: A multidimensional approach to plant adaptation and future implications.

The escalating impact of climate change and ultraviolet (UV) radiation is subjecting plants to unique combinations of UV-B and drought stress. These combined stressors could have additive, synergistic, or antagonistic effects, but the precise nature of these impacts remains uncertain, hampering our ability to predict plant adaptations approach towards stressors. Our analysis of various studies shows that UV-B or drought conditions detrimentally influence plant growth and health metrics by the enhanced generation of reactive oxygen speciescausing damage to lipids, proteins, carbohydrates and DNA. Further reducing biomass accumulation, plant height, photosynthetic efficiency, leaf area, and water transpiration, while enhancing stress-related symptoms. In response to UV-B radiation and drought stress, plants exhibit a notable up-regulation of specific acclimation-associated metabolites, including proline, flavonoids, anthocyanins, unsaturated fatty acids, and antioxidants. These metabolites play a pivotal role in conferring protection against environmental stresses. Their biosynthesis and functional roles are potentially modulated by signalling molecules such as hydrogen peroxide, abscisic acid, jasmonic acid, salicylic acid, and ethylene, all of which have associated genetic markers that further elucidate their involvement in stress response pathways. In comparison to single stress, the combination of UV-B and drought induces the plant defence responses and growth retardation which are less-than-additive. This sub-additive response, consistent across different study environments, suggests the possibility of a cross-resistance mechanism. Our outlines imply that the adverse effects of increased drought and UV-B could potentially be mitigated by cross-talk between UV-B and drought regimes utilizing a multidimensional approach. This crucial insight could contribute significantly to refining our understanding of stress tolerance in the face of ongoing global climate change.

Role of the NLRP1 inflammasome in skin cancer and inflammatory skin diseases.

Inflammasomes are cytoplasmic protein complexes that play a crucial role in protecting the host against pathogenic and sterile stressors by initiating inflammation. Upon activation, these complexes directly regulate the proteolytic processing and activation of proinflammatory cytokines interleukin (IL)-1β and IL-18 to induce a potent inflammatory response, and induce a programmed form of cell death called pyroptosis to expose intracellular pathogens to the surveillance of the immune system, thus perpetuating inflammation. There are various types of inflammasome complexes, with the NLRP1 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-1) inflammasome being the first one identified and currently recognized as the predominant inflammasome sensor protein in human keratinocytes. Human NLRP1 exhibits a unique domain structure, containing both an N-terminal pyrin (PYD) domain and an effector C-terminal caspase recruitment domain (CARD). It can be activated by diverse stimuli, such as viruses, ultraviolet B radiation and ribotoxic stress responses. Specific mutations in NLRP1 or related genes have been associated with rare monogenic skin disorders, such as multiple self-healing palmoplantar carcinoma; familial keratosis lichenoides chronica; autoinflammation with arthritis and dyskeratosis; and dipeptidyl peptidase 9 deficiency. Recent research breakthroughs have also highlighted the involvement of dysfunctions in the NLRP1 pathway in a handful of seemingly unrelated dermatological conditions. These range from monogenic autoinflammatory diseases to polygenic autoimmune diseases such as vitiligo, psoriasis, atopic dermatitis and skin cancer, including squamous cell carcinoma, melanoma and Kaposi sarcoma. Additionally, emerging evidence implicates NLRP1 in systemic lupus erythematosus, pemphigus vulgaris, Addison disease, Papillon-Lefèvre syndrome and leprosy. The aim of this review is to shed light on the implications of pathological dysregulation of the NLRP1 inflammasome in skin diseases and investigate the potential rationale for targeting this pathway as a future therapeutic approach.

α-Tocopherol application as a countermeasure to UV-B stress in bread wheat (Triticum aestivum L.).

The source of energy for all photoautotrophic organisms is light, which is absorbed by photosynthetic processes and used to transform carbon dioxide and H2O into organic molecules. The majority of UV-B light (280 to 320 nm) is absorbed by stratospheric ozone layer, although some of it does reach at the Earth's surface. Because of the sedentary lifestyle of plants, this form of abiotic stress is unavoidable and can induce growth and even cell death. Ten-day-old calli generated from mature Kirik wheat embryos were subjected to UV-B radiation for 0, 2, 4, and 6 h to examine the function of exogenous α-tocopherol, a lipophilic antioxidant, in wheat tolerance to UV-B radiation stress. The calli were then moved to a callus medium containing α-tocopherol (0, 50, and 100 mg/l) and cultivated there for 20 days after being subjected to UV-B stress. For plant regeneration, embryogenic calli were put on a medium for plant regeneration after 30 days. The findings of this investigation demonstrated that an increase in UV-B exposure period resulted in a substantial drop in the relative growth rate of callus, the rate of embryogenic callus, the rate of responding embryogenic callus, and the number of plants in each explant. On the other hand, with the application of α-tocopherol, all these parameters improved, and the best result was observed in the application of 100 mg/l of α-tocopherol in terms of plant regeneration under UV-B stress.

RVE1, DBB1b, and COL2 Transcription Factors Are Responsive to Combined Stress by UV-B Radiation and Cold in Bell Pepper (Capsicum annuum)

Ultraviolet-B radiation (UV-B) and cold limit the growth and development of plants, which generates changes in gene expression. This allows plants to respond to stress through regulatory proteins, such as transcription factors, that activate or repress the expression of stress-response genes. RNA-Seq data and WGCNA analyses were utilized to identify the hub genes. Our study found a total of 25, 24, and 29 transcription factors at different time points T1, T2, and T3, respectively, under combined stress (ultraviolet-B radiation and cold). RVE1 (MYB-related), COL2 (CO-like), and DBB1b (DBB) were identified as candidate hub genes. Moreover, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed that RVE1, DBB1b, and COL2 were mostly involved in energy production, the antioxidant system (enzymatic and non-enzymatic), signaling through abscisic acid and CA2+, response to light stimulus, and cellular homeostasis. These findings provide the basis for further investigation related to UV-B radiation and cold stress response mechanisms in plants.

Tetracarboxylic acid transporter regulates growth, conidiation, and carbon utilization in Metarhizium acridum.

Carbon sources and their utilization are vital for fungal growth and development. C4-dicarboxylic acids are important carbon and energy sources that function as intermediate products of the tricarboxylic acid cycle. Transport and regulation of C4-dicarboxylic acid uptake are mainly dependent on tetracarboxylic acid transporters (Dcts) in many microbes, although the roles of Dct genes in fungi have only been partially characterized. Here, we report on the functions of two Dct genes (Dct1 and Dct2) in the entomopathogenic fungus Metarhizium acridum. Our data showed that loss of the MaDct1 gene affected utilization of tetracarboxylic acids and other carbon sources. ΔMaDct1 mutants showed larger colony sizes with extensive mycelial growth but were delayed in conidiation with decreased conidia yield as compared to the wild-type parental strain. On the nutrient-deficient medium, SYA, the wild-type strain produced microcycle conidia, whereas the ΔMaDct1 mutant produced (normal) aerial conidia. In addition, ΔMaDct1 had decreased tolerance to cell wall perturbing agents, but increased tolerances to UV-B radiation and osmotic stress. Insect bioassays indicated that loss of MaDct1 did not affect pathogenicity. In contrast, no distinct phenotypic change was observed for the MaDct2 mutant in terms of growth and biocontrol characteristics. Transcriptomic profiling between wild type and ΔMaDct1 showed that differentially expressed genes were enriched in carbohydrate and amino acid metabolism, transport and catabolism, and signal transduction. These results demonstrate that MaDct1 regulates the conidiation pattern shift and mycelial growth by affecting utilization of carbon sources. These findings are helpful for better understanding the effect of intermediates of carbon metabolism on fungal growth and conidiation. KEY POINTS: • MaDct1 influences fungal growth and conidiation by affecting carbon source utilization. • MaDct1 regulates conidiation pattern shift under nutrient deficiency condition. • MaDct1 is involved in stress tolerance and has no effect on virulence. • MaDct2 has no effect on growth and biocontrol characteristic.

A Moss 2-Oxoglutarate/Fe(II)-Dependent Dioxygenases (2-ODD) Gene of Flavonoids Biosynthesis Positively Regulates Plants Abiotic Stress Tolerance.

Flavonoids, the largest group of polyphenolic secondary metabolites present in all land plants, play essential roles in many biological processes and defense against abiotic stresses. In the flavonoid biosynthesis pathway, flavones synthase I (FNSI), flavanone 3-hydroxylase (F3H), flavonol synthase (FLS), and anthocyanidin synthase (ANS) all belong to 2-oxoglutarate/Fe(II)-dependent dioxygenases (2-ODDs) family, which catalyzes the critical oxidative reactions to form different flavonoid subgroups. Here, a novel 2-ODD gene was cloned from Antarctic moss Pohlia nutans (Pn2-ODD1) and its functions were investigated both in two model plants, Physcomitrella patens and Arabidopsis thaliana. Heterologous expression of Pn2-ODD1 increased the accumulation of anthocyanins and flavonol in Arabidopsis. Meanwhile, the transgenic P. patens and Arabidopsis with expressing Pn2-ODD1 exhibited enhanced tolerance to salinity and drought stresses, with larger gametophyte sizes, better seed germination, and longer root growth. Heterologous expression of Pn2-ODD1 in Arabidopsis also conferred the tolerance to UV-B radiation and oxidative stress by increasing antioxidant capacity. Therefore, we showed that Pn2-ODD1 participated in the accumulation of anthocyanins and flavonol in transgenic plants, and regulated the tolerance to abiotic stresses in plants, contributing to the adaptation of P. nutans to the polar environment.

Silicon Mitigates Negative Impacts of Drought and UV-B Radiation in Plants.

Due to climate change, plants are being more adversely affected by heatwaves, floods, droughts, and increased temperatures and UV radiation. This review focuses on enhanced UV-B radiation and drought, and mitigation of their adverse effects through silicon addition. Studies on UV-B stress and addition of silicon or silicon nanoparticles have been reported for crop plants including rice, wheat, and soybean. These have shown that addition of silicon to plants under UV-B radiation stress increases the contents of chlorophyll, soluble sugars, anthocyanins, flavonoids, and UV-absorbing and antioxidant compounds. Silicon also affects photosynthesis rate, proline content, metal toxicity, and lipid peroxidation. Drought is a stress factor that affects normal plant growth and development. It has been frequently reported that silicon can reduce stress caused by different abiotic factors, including drought. For example, under drought stress, silicon increases ascorbate peroxidase activity, total soluble sugars content, relative water content, and photosynthetic rate. Silicon also decreases peroxidase, catalase, and superoxide dismutase activities, and malondialdehyde content. The effects of silicon on drought and concurrently UV-B stressed plants has not yet been studied in detail, but initial studies show some stress mitigation by silicon.

A CPD photolyase gene PnPHR1 from Antarctic moss Pohlia nutans is involved in the resistance to UV-B radiation and salinity stress

In Antarctic continent, the organisms are exposed to high ultraviolet (UV) radiation because of damaged stratospheric ozone. UV causes DNA lesions due to the accumulation of photoproducts. Photolyase can repair UV-damaged DNA in a light-dependent process by electron transfer mechanism. Here, we isolated a CPD photolyase gene PnPHR1 from Antarctic moss Pohlia nutans, which encodes a protein of theoretical molecular weight of 69.1 KDa. The expression level of PnPHR1 was increased by UV-B irradiation. Enzyme activity assay in vitro showed that PnPHR1 exhibited photoreactivation activity, which can repair CPD photoproducts in a light-dependent manner. The complementation assay of repair-deficient E. coli strain SY2 demonstrated that PnPHR1 gene enhanced the survival rate of SY2 strain after UV-B radiation. Additionally, overexpression of PnPHR1 enhanced the Arabidopsis resistance to UV-B radiation and salinity stress, which also conferred plant tolerance to oxidative stress by decreasing ROS production and increasing ROS clearance. Our work shows that PnPHR1 encodes an active CPD photolyase, which may participate in the adaptation of P. nutans to polar environments.

Responses of the ecological characteristics and antioxidant enzyme activities in Rotaria rotatoria to UV-B radiation

UV-B radiation is an increasing threat to aquatic organisms and also a potential driving force for zooplankton population dynamics. To explore the ecological effects of UVR on rotifers and the responses of antioxidant system against UVR, the acute lethal effects, the life history strategies, population growth, and antioxidant enzyme activities were assessed in the Bdelloid Rotaria rotatoria after exposure to UV-B radiation. The results indicated that the persistence of tolerance in rotifer to stress was playing a more vital role than the radiation dose in survival. The larger the culture volume, the weaker the lethal effect. Rotifers prolonged their first reproductive time and shortened their reproductive period and longevity with the increasing of radiation dose, and the fecundity was significant inhibited by UV-B radiation. These responses can be taken as energy trade-off to retard their mortality. The population density of the rotifers increased at the lowest dose of radiation and then descended with the increasing of UVR dose, and this pattern was also corroborated by detecting the content of SOD and CAT, which suggested that hormesis also applies to R. rotatoria under UV-B radiation stress. The enzyme SOD has higher level of content and more sensitive to low UVR than CAT.

Abiotic stresses induced physiological, biochemical, and molecular changes in <i>Betula platyphylla</i>: a review

Abiotic stress is one of the major factors in reducing plant growth, development, and yield production by interfering with various physiological, biochemical, and molecular functions. In particular, abiotic stress such as salt, low temperature, heat, drought, UV-radiation, elevated CO2, ozone, and heavy metals stress is the most frequent study in Sukaczev. is one of the most valuable tree species in East Asia facing abiotic stress during its life cycle. Using transgenic plants is a powerful tool to increase the abiotic stress tolerance. Generally, abiotic stress reduces leaves water content, plant height, fresh and dry weight, and enhances shed leaves as well. In the physiological aspect, salt, heavy metal, and osmotic stress disturbs seed germination, stomatal conductance, chlorophyll content, and photosynthesis. In the biochemical aspect, salt, drought, cold, heat, osmotic, UV-B radiation, and heavy metal stress increases the ROS production of cells, resulting in the enhancement of enzymatic antioxidant (SOD and POD) and non-enzymatic antioxidant (proline and AsA) to reduce the ROS accumulation. Meanwhile, upregulates various genes, as well as proteins to participate in abiotic stress tolerance. Based on recent studies, several transcription factors contribute to increasing abiotic stress tolerance in , including , and . These transcription factors bind to different cis-acting elements to upregulate abiotic stress-related genes, resulting in the enhancement of salt, drought, cold, heat, osmotic, UV-B radiation, and heavy metal tolerance. These genes along with phytohormones mitigate the abiotic stress. This review also highlights the candidate genes from another Betulacea family member that might be contributing to increasing abiotic stress tolerance.Betula platyphyllaBetula platyphyllaB. platyphyllaB. platyphyllaB. platyphyllaB. platyphyllaBplMYB46, BpMYB102, BpERF13, BpERF2, BpHOX2, BpHMG6, BpHSP9, BpUVR8, BpBZR1, BplERD15BpNACsB. platyphylla

ELONGATED HYPOCOTYL5 Negatively Regulates DECREASE WAX BIOSYNTHESIS to Increase Survival during UV-B Stress.

Understanding how the distinct cell types of the shoot apical meristem (SAM) withstand ultraviolet radiation (UVR) stress can improve cultivation of plants in high-UVR environments. Here, we show that UV-B irradiation selectively kills epidermal and niche cells in the shoot apex. Plants harboring a mutation in DECREASE WAX BIOSYNTHESIS (DEWAX) are tolerant to UV-B. Our data show that DEWAX negatively regulates genes involved in anthocyanin biosynthesis. ELONGATED HYPOCOTYL5 (HY5) binds to the DEWAX promoter elements and represses its expression to promote the anthocyanin biosynthesis. The HY5-DEWAX regulatory network regulates anthocyanin content in Arabidopsis (Arabidopsis thaliana) and influences the survivability of plants under UV-B irradiation stress. Our cell sorting-based study of the epidermal cell layer transcriptome confirms that core UV-B stress signaling pathway genes are conserved and upregulated in response to UV-B irradiation of the SAM. Furthermore, we show that UV-B induces genes involved in shoot development and organ patterning. We propose that the HY5-DEWAX regulatory relationship is conserved; however, changes in the expression levels of these genes can determine anthocyanin content in planta and, hence, fitness under UV-B irradiation stress.

Effects of Exogenous Soybean Isoflavones on Physiological Parameters of Achyranthes bidentata Blume Seedlings under UV-B Radiation Stress

In this study, effects of soy isoflavones (SIF) on the growth and development, physiology, content of medicinal ingredients and expression levels of enzyme-encoding genes in Achyranthes bidentata Blume under UV-B radiation were systematically investigated. The results showed that UV-B radiation adversely affected the growth and development of A. bidentata seedlings, causing ROS accumulation and the anti-oxidation system to be damaged. However, 1 mg/L exogenous SIF treatment conferred enhanced tolerance under UV-B radiation stress in A. bidentata seedlings by decreasing the concentration of MDA, H2O2, and modulating SOD and POD activities. Furthermore, 1 mg/L SIF reduced the content of oleanolic acid and ecdysterone in leaves and increased the content of oleanolic acid in roots, but had no significant effect on the content of ecdysterone in roots under UV-B radiation stress. SIF had a different degree of influence on the expression levels of antioxidant enzyme genes as well as medicinal ingredients enzyme-encoding genes in A. bidentata. The results showed that 1 mg/L exogenous SIF treatment had a positive effect on the growth, development and physiology in A. bidentata seedlings under UV-B radiation stress. To our knowledge, for the first time we are reporting that the use of 1 mg/L exogenous SIF enhances A. bidentata seedlings tolerance to UV-B radiation stress.

Assessment of Protective Mechanisms against Ultra Violate–B Elevation in Tow Species of Palms Seedling Grown Under Laboratory Conditions

The present study was carried out for examining the alterations of total chlorophyll and antioxidants contents (carotenoids, phenols and proline), on two species of palm seedlings, Date palm (Phoenix dactylifera L.) and Washingtonian palm (Washingtonia filifera induced by exposure to UV-B radiations at different periods (2,4,8 and 10 hrs/day). Results showed that the 30 days of UV-B treatment for 2 and 4 hrs./ day caused significantly increased in total chlorophyll contents of both palm seedling species. While the lowest contents of chlorophyll were obtained in plants grown under UV-B radiation stress for 10 hrs./day. On the contrary, the highest value of carotenoids content was recorded after 8 hrs./day of treatment with UV, then it reduced after treated with 10 hrs./day. Similarly, the content of total phenol and proline showed significantly increased with increasing time of UV-B exposed in both species. The study also revealed a significant difference between two palm species in terms of tolerance to UV-B, where it was found that the Date palm (Phoenix dactylifera L.) seedlings were more resistance to such radiation than (Washingtonia filifera ).

Enhanced UV-B radiation aggravates negative effects more in females than in males of Morus alba saplings under drought stress

Drought and UV-B radiation are two major environmental stresses which can either suppress or activate defense responses in plants. What is less clear is how these stresses, separately or combined, affect the male and female plants of dioecious species. Mulberry (Morus alba L.) saplings, a dioecious plant widely planted in China and Japan, was employed as a model species and subjected to two UV-B radiation regimes (3.43 kJ m–2 day–1 (ambient radiation) and 3.78 kJ m–2 day–1 biologically effective UV-B radiation (enhanced radiation)) and two watering regimes (100 and 30% of the field capacity) for 3 months, and then sex-related morphological, physiological, anatomical and ultrastructural responses of mulberry to enhanced UV-B radiation and drought were investigated. Compared with the control, both enhanced UV-B radiation and drought significantly inhibited growth of both sexes and the effects were not fully additive. This might indicate that one of the two stress factors activated defense responses in the plants which reduced the damage caused by the other. Furthermore, when exposed to the combination of enhanced UV-B radiation and drought stress, females exhibited significantly lower morphological increment of stem and root, biomass accumulation, net photosynthesis rate, antioxidative enzymes activities, anthocyanin content, total leaf area and relative water content, as well as more damage on mesophyll cells than did males. Therefore, these results indicated that enhanced UV-B radiation aggravates negative effects more in female saplings than in males under drought stress

Effects of UV-B radiation on the survival, egg hatchability and transcript expression of antioxidant enzymes in a high-temperature adapted strain of Neoseiulus barkeri.

Biological control of spider mites in hot and dry weather is a serious technical issue. A high-temperature adapted strain (HTAS) of the predatory mite Neoseiulus barkeri Hughes was selected from its conventional strain (CS), via long-term heat acclimation and frequent heat hardenings in our previous studies. However, the environment of high temperature is usually associated with enhanced ultraviolet (UV) radiation. In the present study, the physiological effects of UV-B radiation on survival rate and egg damage of N. barkeri were investigated, as well as the activities and expression profiles of antioxidant enzymes to UV-B radiation stress. UV-B radiation had deleterious effects on egg hatchability and survival of N. barkeri. Adults of the HTAS strain were less UV-B resistant than those of the CS strain; they also had lower levels of enzymatic activity of superoxide dismutase (SOD) and catalase against oxidative damage and weaker upregulation of SOD genes. The mRNA expression of three SOD genes of CS adult females immediately increased whereas that of HTAS showed almost no difference under UV-B stress for 1h. The results showed the HTAS of N. barkeri had lower fitness under UV-B stress compared with the CS of N. barkeri. These results suggested that long-term heat acclimation may exert a profound impact on the developmental physiology of N. barkeri.

Visual Quality and Morphological Responses of Rosemary Plants to UV-B Radiation and Salinity Stress

Visual Quality and Morphological Responses of Rosemary Plants to UV-B Radiation and Salinity Stress

Metabolomic elucidation of recovery of Melissa officinalis from UV-B irradiation stress

UV irradiation is a major stress and leads to the accumulation of secondary metabolites in plants as a protective mechanism. The altered metabolism caused by the stress will eventually return to basal conditions, however, the recovery mechanism after UV irradiation stress remains unknown. To understand how plant metabolism recovers following UV irradiation stress, global metabolite profiling of Melissa officinalis (lemon balm) was performed using gas chromatography/mass spectrometry (GC/MS). Principal component and hierarchical clustering analyses showed the significant discrimination of metabolite profiles between the control (non-irradiated), UV-irradiated M. officinalis, and M. officinalis allowed to recover from the UV stress. The glycolysis and phenylpropanoid pathway rapidly reverted to their original states. In contrast, the TCA cycle and amino acid biosynthesis returned slowly to their original states. This study determined that the metabolism and metabolite levels recover their original conditions after the removal of UV irradiation, and that the recovery time of each metabolic pathway differs.