Heme oxygenase up-regulation under ultraviolet-B radiation is not epigenetically restricted and involves specific stress-related transcriptions factors

Heme oxygenase-1/carbon monoxide signaling participates in the accumulation of triterpenoids of Ganoderma lucidum

Ganoderic triterpenoids (GTs) are the primary bioactive constituents of the Basidiomycotina fungus, Ganoderma lucidum. These compounds exhibit antitumor, anti-hyperlipidemic, and immune-modulatory pharmacological activities. This study focused on GT accumulation in mycelia of G. lucidum mediated by the heme oxygenase-1 (HO-1)/carbon monoxide (CO) signaling. Compared with the control, hemin (10 μmol/L) induced an increase of 60.1% in GT content and 57.1% in HO-1 activity. Moreover, carbon monoxide-releasing molecule-2 (CORM-2), CO donor, increased GT content by 56.0% and HO-1 activity by 18.1%. Zn protoporphyrin IX (ZnPPIX), a specific HO-1 inhibitor, significantly reduced GT content by 26.0% and HO-1 activity by 15.8%, while hemin supplementation reversed these effects. Transcriptome sequencing showed that HO-1/CO could function directly as a regulator involved in promoting GT accumulation by regulating gene expression in the mevalonate pathway, and modulating the reactive oxygen species (ROS) and Ca²⁺ pathways. The results of this study may help enhance large-scale GT production and support further exploration of GT metabolic networks and relevant signaling cross-talk.

Enhancement of soybean nodulation by seed treatment with non-thermal plasmas

Soybean (Glycine max (L.) Merrill) is one of the most important crops worldwide providing dietary protein and vegetable oil. Most of the nitrogen required by the crop is supplied through biological N2 fixation. Non-thermal plasma is a fast, economical, and environmental-friendly technology that can improve seed quality, plant growth, and crop yield. Soybean seeds were exposed to a dielectric barrier discharge plasma operating at atmospheric pressure air with superimposed flows of O2 or N2 as carrying gases. An arrangement of a thin phenolic sheet covered by polyester films was employed as an insulating barrier. We focused on the ability of plasma to improve soybean nodulation and biological nitrogen fixation. The total number of nodules and their weight were significantly higher in plants grown from treated seeds than in control. Plasma treatments incremented 1.6 fold the nitrogenase activity in nodules, while leghaemoglobin content was increased two times, indicating that nodules were fixing nitrogen more actively than control. Accordingly, the nitrogen content in nodules and the aerial part of plants increased by 64% and 23%, respectively. Our results were supported by biometrical parameters. The results suggested that different mechanisms are involved in soybean nodulation improvement. Therefore, the root contents of isoflavonoids, glutathione, auxin and cytokinin, and expansin (GmEXP1) gene expression were determined. We consider this emerging technology is a suitable pre-sowing seed treatment.

EsHO 1 mediated mitigation of NaCl induced oxidative stress and correlation between ROS, antioxidants and HO 1 in seedlings of Eruca sativa: underutilized oil yielding crop of arid region

Study have focused on NaCl induced HO 1 production and its co-relation to ROS and antioxidant regulation in Eruca sativa. Seedlings were subjected to NaCl stress ranges from 10 to 150 mM. After 96 h of treatment, plants samples were harvested to evaluate the cellular equilibrium and salt tolerance mechanisms through morphological, stress parameters, non enzymatic and antioxidant enzymes. The HO 1 activity was found to be highest at 75 mM NaCl in leaves and roots which were 2.49 and 2.02 folds respectively. The expression of EsHO 1 was also observed and the higher expression was recorded in roots than leaves. The overall activity of other antioxidants (APX and proline) was also found to be higher at 75 mM concentration. The highest HO 1 activity with other antioxidants indicates the decline in LPX and ROS at 75 mM NaCl. The present study concluded that HO 1 helps in amelioration of NaCl stress by working within a group of antioxidants that create the defense machinery in seedlings of E. sativa by manipulating various physiological processes of plants. These findings for the first time suggest the protective role of HO 1 in scavenging ROS in E. sativa under salinity stress.

Anti-photoaging effects of solvent-partitioned fractions from Portulaca oleracea L. on UVB-stressed human keratinocytes

In this study, the anti-photoaging activity of solvent-fractionated extracts from Portulaca oleracea L. was investigated in ultraviolet B-stressed keratinocytes. The results showed that the treatment of the fractions suppressed the generation of intracellular reactive oxygen species (ROS) and activated mRNA and protein expression levels of superoxide dismutase1 (SOD-1) and heme oxygenase1 (HO-1) enzymes via Nrf-2 pathway. The tested fractions down-regulated the expression of matrix metalloproteinases (MMPs) and up-regulated type Ⅰ procollagen production. Among the tested samples, the 85% aq. MeOH fraction was the most effective in suppressing MMPs and type Ⅰ procollagen degradation. Two homoisoflavonoids, portulacanone A (PA) and portulacanon D (PD), were isolated from the 85% aq. MeOH fraction. PA and PD successfully inhibited the secretionof MMP-1 and increased the production of type Ⅰ procollagen in UVB-stressed keratinocytes. Therefore, solvent-partitioned factions from P. oleracea and its active components, PA and PD, were suggested to have beneficial effects against photoaging. PRACTICAL APPLICATIONS: Portulaca oleracea L. is an edible nutrient-rich herb with high amounts of omega-3 and omega-6 fatty acids, ascorbic acid, and dietary minerals. P. oleracea has also been used as a botanical medicine for its potential health benefits such as antioxidant, antibacterial, and antiinflammatory properties. The current study suggested that the extracts from P. oleracea were able to prevent human keratinocytes from UVB-induced stress and damage. Due to its protective abilities, it can be used as an additive in the cosmeceutical industry to produce novel skin protectants. In addition, due to its intracellular antioxidant and MMP inhibitory effects, it can be a valuable source for nutraceutical development. Further studies that characterize the isolated flavonoids may also yield bioactive molecules to be utilized in cosmeceutical and nutraceutical industries as lead compounds. Nevertheless, P. oleracea can serve as a health beneficial addition to topical applications and dietary supplements against UVB-stimulated oxidative stress in skin cells.

Haem oxygenase: A functionally diverse enzyme of photosynthetic organisms and its role in phytochrome chromophore biosynthesis, cellular signalling and defence mechanisms

Haem oxygenase (HO) is a universal enzyme that catalyses stereospecific cleavage of haem to BV IX α and liberates Fe⁺² ion and CO as by-product. Beside haem degradation, it has important functions in plants that include cellular defence, stomatal regulation, iron mobilization, phytochrome chromophore synthesis, and lateral root formation. Phytochromes are an extended family of photoreceptors with a molecular mass of 250 kDa and occur as a dimer made up of 2 equivalent subunits of 125 kDa each. Each subunit is made of two components: the chromophore, a light-capturing pigment molecule and the apoprotein. Biosynthesis of phytochrome (phy) chromophore includes the oxidative splitting of haem to biliverdin IX by an enzyme HO, which is the decisive step in the biosynthesis. In photosynthetic organisms, BVα is reduced to 3Z PΦB by a ferredoxin-dependent PΦB synthase that finally isomerised to PΦB. The synthesized PΦB assembles with the phytochrome apoprotein in the cytoplasm to generate holophytochrome. Thus, necessary for photomorphogenesis in plants, which has confirmed from the genetic studies, conducted on Arabidopsis thaliana and pea. Besides the phytochrome chromophore synthesis, the review also emphasises on the current advances conducted in plant HO implying its developmental and defensive role.

Evaluation of heme oxygenase 1 (HO 1) in Cd and Ni induced cytotoxicity and crosstalk with ROS quenching enzymes in two to four leaf stage seedlings of Vigna radiata

Research on heme oxygenase in plants has received consideration in recent years due to its several roles in development, defense, and metabolism during various environmental stresses. In the current investigation, the role of heme oxygenase (HO) 1 was evaluated in reducing heavy metal (Cd and Ni) uptake and alleviating Cd and Ni toxicity effects in the hydroponically grown seedlings of Vigna radiata var. PDM 54. Seedlings were subjected to Cd- and Ni-induced oxidative stress independently at different concentrations ranging from 10 to 100 μM. After 96 h (fourth day) of treatment, the stressed plants were harvested to study the cellular homeostasis and detoxification mechanism by examining the growth, stress parameters (LPX, H₂O₂ content), and non-enzymatic and enzymatic parameters (ascorbate peroxidase (APX), guaicol peroxidase (GPX), and catalase (CAT)) including HO 1. At 50 μM CdCl₂ and 60 μM NiSO₄, HO 1 activity was found to be highest in leaves which were 1.39 and 1.16-fold, respectively. The greatest HO 1 activity was reflected from the reduction of H₂O₂ content at these metal concentrations (50 μM CdCl₂ and 60 μM NiSO₄) which is correlated with the increasing activity of other antioxidant enzymes (CAT, APX). Thus, HO 1 works within a group that generates the defense machinery for the plant's survival by scavenging ROS which is confirmed by a time-dependent study. Hence, it is concluded that seedlings of V. radiata were more tolerant towards metal-induced oxidative stress in which HO 1 is localized in its residential area (plastids).