scholarly journals Nectar defense and hydrogen peroxide in floral nectar of Cucurbita pepo

2015 ◽  
Vol 68 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Daniele Nocentini ◽  
Massimo Guarnieri ◽  
Chiara Soligo
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Cucurbita Pepo ◽  
Defense Mechanism ◽  
Starch Accumulation ◽  
Floral Nectar ◽  
Male Flowers ◽  
Female Flowers

This study was carried out to investigate some similarities between the nectaries of <em>Nicotiana</em> sp. and <em>Cucurbita</em> pepo, such as starch accumulation in the nectary parenchyma, changes in nectary color during maturation, and the production of a large quantity of sucrose-dominant nectar. The concentration of hydrogen peroxide in <em>C. pepo</em> floral nectar was determined in order to verify the presence of a defense mechanism similar to that found in <em>Nicotiana</em> sp. which protects nectar from yeast and bacteria proliferation. We also tested the eventual accumulation of antioxidants in the nectary of <em>C. pepo</em> as a protection against oxidative stress caused by hydrogen peroxide. The level of hydrogen peroxide found in the floral nectar of <em>C. pepo</em> was much lower than that found in <em>Nicotiana</em> sp. and the male flowers of <em>Cucurbita</em> had a higher concentration than the female flowers. The low oxidative stress induced by this level of hydrogen peroxide caused the accumulation of a low amount of lutein inside the plastoglobules which were contained in amyloplasts. Plastids of the <em>C. pepo</em> nectary are specialized in the accumulation of starch rather than antioxidants.

scholarly journals Melatonin alleviates heat-induced damage of tomato seedlings by balancing redox homeostasis and modulating polyamine and nitric oxide biosynthesis

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Mohammad Shah Jahan ◽  
Sheng Shu ◽  
Yu Wang ◽  
Zheng Chen ◽  
Mingming He ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Nitric Oxide ◽  
Hydrogen Peroxide ◽  
Heat Stress ◽  
Heat Shock ◽  
Defense Mechanism ◽  
Enzymatic Antioxidants ◽  
Tomato Seedlings ◽  
Glutathione Cycle

Abstract Background Melatonin is a pleiotropic signaling molecule that plays multifarious roles in plants stress tolerance. The polyamine (PAs) metabolic pathway has been suggested to eliminate the effects of environmental stresses. However, the underlying mechanism of how melatonin and PAs function together under heat stress largely remains unknown. In this study, we investigated the potential role of melatonin in regulating PAs and nitric oxide (NO) biosynthesis, and counterbalancing oxidative damage induced by heat stress in tomato seedlings. Results Heat stress enhanced the overproduction of reactive oxygen species (ROS) and damaged inherent defense system, thus reduced plant growth. However, pretreatment with 100 μM melatonin (7 days) followed by exposure to heat stress (24 h) effectively reduced the oxidative stress by controlling the overaccumulation of superoxide (O2•−) and hydrogen peroxide (H2O2), lowering the lipid peroxidation content (as inferred based on malondialdehyde content) and less membrane injury index (MII). This was associated with increased the enzymatic and non-enzymatic antioxidants activities by regulating their related gene expression and modulating the ascorbate–glutathione cycle. The presence of melatonin induced respiratory burst oxidase (RBOH), heat shock transcription factors A2 (HsfA2), heat shock protein 90 (HSP90), and delta 1-pyrroline-5-carboxylate synthetase (P5CS) gene expression, which helped detoxify excess ROS via the hydrogen peroxide-mediated signaling pathway. In addition, heat stress boosted the endogenous levels of putrescine, spermidine and spermine, and increased the PAs contents, indicating higher metabolic gene expression. Moreover, melatonin-pretreated seedlings had further increased PAs levels and upregulated transcript abundance, which coincided with suppression of catabolic-related genes expression. Under heat stress, exogenous melatonin increased endogenous NO content along with nitrate reductase- and NO synthase-related activities, and expression of their related genes were also elevated. Conclusions Melatonin pretreatment positively increased the heat tolerance of tomato seedlings by improving their antioxidant defense mechanism, inducing ascorbate–glutathione cycle, and reprogramming the PAs metabolic and NO biosynthesis pathways. These attributes facilitated the scavenging of excess ROS and increased stability of the cellular membrane, which mitigated heat-induced oxidative stress.

scholarly journals The morphology and ultrastructure of the nectaries of marrow (Cucurbita pepo L. convar. giromontiina)

2013 ◽  
Vol 66 (3) ◽  
pp. 11-22 ◽  
Author(s):  
Marta Dmitruk ◽  
Elżbieta Weryszko-Chmielewska
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cucurbita Pepo ◽  
Female Flower ◽  
Transmission Electron ◽  
Parenchyma Cells ◽  
Male Flowers ◽  
Nectariferous Tissue ◽  
Female Flowers ◽  
Size And Structure

The present study investigated the size and structure of the nectaries in flowers of marrow – <em>Cucurbita pepo </em>convar.<em> giromontiina </em>cv. ‘Weiser Busch’. The diameter and thickness of nectariferous layer were compared in female and male flowers of this taxon. The micromorphology as well as the anatomical and ultrastructural characters of the nectary from the female flower were observed using light, scanning and transmission electron microscopy. The density and size of stomata of the nectary epidermis from both types of flowers were examined using light microscopy. The nectaries in female flowers were found to have a larger size than in male flowers. The stomata occurring in the nectary epidermis of both types of flowers have a similar size and density. We observed that nectar was released onto the surface of the nectary not only via the stomata, but also through the walls of the epidermal cells. In TEM examination, large nuclei, different-shaped plastids, ER tubules, dictyosomes, and ribosomes were observed in the nectariferous tissue cells. A large number of mitochondria accompanying the plastids were found in the parenchyma cells of the nectary. The degradation of the nectary parenchyma cells in the flowers living for about 6 hours was asynchronous.

scholarly journals Pollination and Fruit Set of Pumpkins in Growers' Fields in New York's Capital District

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 462D-462
Author(s):  
H. Chris Wien ◽  
Dale Riggs
Keyword(s):  
Apis Mellifera ◽  
Cucurbita Pepo ◽  
Fruit Set ◽  
Rating Scale ◽  
Female Flower ◽  
Stigmatic Surface ◽  
Black Light ◽  
Pollen Removal ◽  
Male Flowers ◽  
Female Flowers

Reports of sharply reduced feral bee populations (Apis mellifera) due to harsh winters and prevalence of several bee diseases have raised concerns that pollination and fruit set in pumpkin fields will be adversely affected. In 1995 and 1996, five and eight pumpkin (Cucurbita pepo) fields, respectively, were inventoried on three occasions per season for pollinator activity and percent fruit set. Pollen removal from male flowers was determined visually using a rating scale, while deposition of pollen on stigmata of female flowers was judged by rating fluorescence of pollen on the stigmatic surface under a “black light.” Samples were taken from 15 to 30 locations in each field, and female flowers tagged. These were considered set if they had enlarged to fist size within 14 days. In both years, the amount of pollen remaining on male flowers was negatively correlated with female flower fluorescence ratings. Neither pollen on male flowers nor stigma fluorescence were significantly correlated with percent fruit set. Fifty-two percent of tagged flowers set fruit in both years, with a range of 24% to 84%, and 17% to 78% in 1995 and 1996, respectively. Presence of bee hives in or near the fields had no effect on fruit set. The results indicate that the pollen removal and deposition ratings used were not reliable for predicting fruit set in farmers' fields. In these 2 years, bee hives were not needed in the sampled fields.

scholarly journals Flowering biology, nectar production and insect visits in Cucurbita pepo L. flowers

2012 ◽  
Vol 59 (1) ◽  
pp. 183-197
Author(s):  
Marta Dmitruk
Keyword(s):  
Honey Bees ◽  
Cucurbita Pepo ◽  
Sugar Content ◽  
Nectar Production ◽  
The Mean ◽  
Male Flowers ◽  
Female Flowers

In 1998-2000 studies on length and abundance of flowering and on nectar productivity of zucchini and marrow (<i>Cucurbita pepo</i> L.) were carried out in Lublin area. Flowers visitors were also monitored. Flowering of plants lasted from the end of June till the end of September. The mean number of flowers per plant of zucchini reached: 31 (male flowers) and 26 (female flowers), and for marrow 226 and 22, respectively. Flowers lived, on average, for 5 hours. Female flowers of marrow secreted the highest amount of nectar - 1.354 g per 10 flowers, on average. Sugar content in nectar was 21.84%-27.31%. The mean total amount of sugars secreted by 10 flowers of <i>Cucurbita pepo</i> L. was 21.5-304.3 mg. Pollinators were mainly bumblebees and honey bees.

scholarly journals Use of video surveillance to measure the influences of habitat management and landscape composition on pollinator visitation and pollen deposition in pumpkin (Cucurbita pepo) agroecosystems

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1342 ◽  
Author(s):  
Benjamin W. Phillips ◽  
Mary M. Gardiner
Keyword(s):  
Video Surveillance ◽  
Habitat Management ◽  
Cucurbita Pepo ◽  
Landscape Composition ◽  
Pollen Deposition ◽  
Male And Female ◽  
Flower Visitation ◽  
Visitation Frequency ◽  
Male Flowers ◽  
Female Flowers

Pumpkin (Cucurbita pepo) production relies on insect-mediated pollination, which is provided by managed and wild pollinators. The goals of this study were to measure the visitation frequency, longevity and temporal activity patterns of pumpkin pollinators and to determine if local habitat management and landscape composition affected this pollination service. We used video surveillance to monitor bee acitivty within male and female pumpkin flowers in 2011 and 2012 across a pollination window of 0600–1200 h. We also quantified the amount of pollen deposited in female flowers across this time period. In 2011,A. melliferamade significantly more floral visits than other bees, and in 2012Bombus spp. was the dominant pumpkin pollinator. We found variation in visitation among male and female pumpkin flowers, withA. melliferavisiting female flowers more often and spending longer per visit within them than male flowers in both 2011 and 2012. The squash beeP. pruinosavisited male flowers more frequently in 2012, but individuals spent equal time in both flower sexes. We did not find variation in the timing of flower visitation among species across the observed pollination window. In both 2011 and 2012 we found that the majority of pollen deposition occurred within the first two hours (0600–0800 h) of observation; there was no difference between the pollen deposited during this two-hour period and full pollination window (0600–1200 h). Local additions of sweet alyssum floral strips or a field buffer strip of native wildflowers did not have an effect on the foraging activity of bees or pollen deposition. However, semi-natural and urban habitats in the surrounding landscape were positively correlated with the frequency of flower visitation by wild pollinators and the amount of pollen deposited within female flowers.

Induction of resistance to hydrogen peroxide and radiation inDeinococcus radiodurans

1995 ◽  
Vol 41 (2) ◽  
pp. 170-176 ◽  
Author(s):  
Ping Wang ◽  
Herb E. Schellhorn
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Defense Mechanism ◽  
Deinococcus Radiodurans ◽  
Inducible Defense ◽  
Dna Damaging Agents ◽  
Radiation Resistant ◽  
Γ Rays ◽  
Induction Of Resistance ◽  
Mutagenic Effects

Though bacteria of the radiation-resistant genus Deinococcus have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. To investigate antioxidant enzyme responses in Deinococcus spp., the catalase activity produced by these bacteria was measured and the sensitivity of these bacteria to hydrogen peroxide was tested. Deinococcus spp. had higher levels of catalase and were more resistant to hydrogen peroxide than Escherichia coli K12. The high levels of catalase produced by Deinococcus radiodurans were, in part, regulated by growth phase. Cultures of D. radiodurans, when pretreated with sublethal levels of hydrogen peroxide, became relatively resistant to the lethal effects of hydrogen peroxide and exhibited higher levels of catalase than untreated control cultures. These pretreated cells were also resistant to lethality mediated by ultraviolet light and γ-rays. These results suggest that Deinococcus spp. possess inducible defense mechanism(s) against the deleterious effects of oxidants and ionizing and ultraviolet radiation.Key words: catalase, oxidative stress, radiation resistance, Deinococcus spp.

Effect of Turmeric and Ginger on Lipid Profile in Male Rats Exposed to Oxidative Stress

2019 ◽  
Vol 10 (01) ◽  
Author(s):  
Eman A. Al-Rekabi ◽  
Dheyaa K. Alomer ◽  
Rana Talib Al-Muswie ◽  
Khalid G. Al-Fartosi
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Drinking Water ◽  
Lipid Profile ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Male Rats ◽  
Control Group ◽  
Very Low Density Lipoprotein ◽  
Low Density

The present study aimed to investigate the effect of turmeric and ginger on lipid profile of male rats exposed to oxidative stress induced by hydrogen peroxide H2O2 at a concentration of 1% given with consumed drinking water to male rats. Methods: 200 mg/kg from turmeric and ginger were used, and the animals were treatment for 30 days. Results: the results showed a significant increase in cholesterol, triglycerides, low density lipoprotein (LDL), very low density lipoprotein (VLDL), whereas it explained a significant decrease in high density lipoprotein (HDL) of male rats exposed to oxidative stress when compared with control group. the results showed a significant decrease in cholesterol, triglycerides, (LDL), (VLDL), whereas it explained a significant increase in (HDL) of rats treated with turmeric and ginger at dose 200 mg/kg when compared with male rats exposed to oxidative stress.

Antioxidative Effect of Rhus javanica Linne Extract Against Hydrogen Peroxide or Menadione Induced Oxidative Stress and DNA Damage in HepG2Cells

2004 ◽  
Vol 9 (2) ◽  
pp. 150-155 ◽  
Author(s):  
Chi-Sung Chun ◽  
Ji-Hyun Kim ◽  
Hyun-Ae Lim ◽  
Ho-Yong Sohn ◽  
Kun-Ho Son ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Antioxidative Effect

Hydrogen peroxide and quercetin induced changes on cell viability, apoptosis and oxidative stress in HepG2 cells

2020 ◽  
Vol 01 ◽  
Author(s):  
Ayşe Mine Yılmaz ◽  
Gökhan Biçim ◽  
Kübra Toprak ◽  
Betül Karademir Yılmaz ◽  
Irina Milisav ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
Hydrogen Peroxide ◽  
Cell Viability ◽  
Hepg2 Cells ◽  
Proteasome Activity ◽  
Cell Cycle Phases ◽  
Induced Changes ◽  
And Oxidative Stress ◽  
Quercetin Treatment

Background: Different cellular responses influence the progress of cancer. In this study, we have investigated the effect of hydrogen peroxide and quercetin induced changes on cell viability, apoptosis and oxidative stress in human hepatocellular carcinoma (HepG2) cells. Methods: The effects of hydrogen peroxide and quercetin on cell viability, cell cycle phases and oxidative stress related cellular changes were investigated. Cell viability was assessed by WST-1 assay. Apoptosis rate, cell cycle phase changes and oxidative stress were measured by flow cytometry. Protein expressions of p21, p27, p53, NF-Kβ-p50 and proteasome activity were determined by Western blot and fluorometry, respectively. Results: Hydrogen peroxide and quercetin treatment resulted in decreased cell viability and increased apoptosis in HepG2 cells. Proteasome activity was increased by hydrogen peroxide but decreased by quercetin treatment. Conclusion: Both agents resulted in decreased p53 protein expression and increased cell death by different mechanisms regarding proteostasis and cell cycle phases.

Sign in / Sign up

Export Citation Format

Share Document