Antifungal Activity of the Extract of a Macroalgae, Gracilariopsis persica, against Four Plant Pathogenic Fungi.

Nowadays, the extract of seaweeds has drawn attention as a rich source of bioactive metabolites. Seaweeds are known for their biologically active compounds whose antibacterial and antifungal activities have been documented. This research aimed to study the profile of phenolic compounds using the HPLC method and determine biologically active compounds using the GC-MS method and the antifungal activity of Gracilariopsis persica against plant pathogenic fungi. G. persica was collected from its natural habitat in Suru of Bandar Abbas, Iran, dried, and extracted by methanol. The quantitative results on phenolic compounds using the HPLC method showed that the most abundant compounds in G. persica were rosmarinic acid (20.9 ± 0.41 mg/kg DW) and quercetin (11.21 ± 0.20 mg/kg DW), and the least abundant was cinnamic acid (1.4 ± 0.10 mg/kg DW). The GC-MS chromatography revealed 50 peaks in the methanolic extract of G. persica, implying 50 compounds. The most abundant components included cholest-5-en-3-ol (3 beta) (27.64%), palmitic acid (17.11%), heptadecane (7.71%), and palmitic acid methyl ester (6.66%). The antifungal activity of different concentrations of the extract was determined in vitro. The results as to the effect of the alga extract at the rates of 200, 400, 600, 800, and 1000 µL on the mycelial growth of four important plant pathogenic fungi, including Botrytis cinerea, Aspergillus niger, Penicillium expansum, and Pyricularia oryzae, revealed that the mycelial growth of all four fungi was lower at higher concentrations of the alga extract. However, the extract concentration of 1000 µL completely inhibited their mycelial growth. The antifungal activity of this alga may be related to the phenolic compounds, e.g., rosmarinic acid and quercetin, as well as compounds such as palmitic acid, oleic acid, and other components identified using the GC-MS method whose antifungal effects have already been confirmed.

Cadmium accumulation, translocation factor, and health risk potential in a wastewater-irrigated soil-wheat (Triticum aestivum L.) system.

The accumulation of trace elements in wastewater-irrigated soils may introduce them to the food chain and therefore can threaten human health. The present study investigated the accumulation, translocation factor, and health risk potential of cadmium (Cd) in a soil-wheat system irrigated with treated wastewater compared with a reference soil (irrigated with fresh water). All treated wastewater-irrigated soils showed significantly higher levels of electrical conductivity (EC) than that of reference soil by 75-143%. Irrigation with treated wastewater increased both available and total Cd content in soil by 2-4 times. In all irrigated sites, Cd content was about twice as great as the maximum acceptable rate. Bioconcentration factor (BCF) and translocation factor (TF) indicated that Cd was mainly accumulated in the roots (BCF = 2.2-3.1), while little mobilization from roots to stems and grains was noted (TFshoot/root = 0.07-0.21; TFgrain/root = 0.18-0.24). The average hazard quotient (HQ) for different age groups of the population varied in the range of 0.1-1.0, implying low non-carcinogenic health risk of Cd to local wheat-consuming residents. The risk of Cd to cause carcinogenic health risk (CR) was in the range of 1 × 10-5 to 1 × 10-4, indicating low to moderate potential risk. CR for different age groups was in the order: individuals above 18 years old > individuals 7-18 years old > individuals 0-6 years old. For reducing potential health risks to local people, it is imperative to continuously monitor heavy metal levels in the wheat-soil system and urgently adopt more efficient managerial strategies to reduce Cd contamination.

Heavy metal bioavailability and accumulation in winter wheat (Triticum aestivum L.) irrigated with treated wastewater in calcareous soils.

Irrigation with raw or diluted wastewater increases in many developing countries, but the increasing availability and use of wastewater generates challenges for public agencies charged with minimizing potential impacts on public health and the environment. In this study, the available (DTPA-extractable) concentration of Zn, Cu, Cd, Pb, and Ni in the surface soil was measured in five sites irrigated with treated wastewater as compared with a site irrigated with freshwater (control). The major sources of wastewater were municipal wastewater, household, commercial, and industrial effluents, which were treated to settle and remove solids prior its use for irrigation. In addition, the concentration of the above five heavy metals and their accumulation and mobilization characteristics were determined in the roots, shoots, and grains of winter wheat (Triticum aestivum L.) grown in treated wastewater-irrigated soils. Irrigation with treated wastewater resulted in a remarkable build-up of metal concentrations in the soil (averaged over five sites) in the order of Cd (178.2%) > Ni (105.1%) > Cu (66.4%) > Zn (66.0%) > Pb (40.9%) compared with control. However, only Cd concentration exceeded the permissible range. The concentration of heavy metals was significantly greater (P < 0.05) in wheat roots than in shoots and grains (root ≫ shoot > grain). The highest concentrations were found in the roots in the order of Cu > Zn > Pb > Cd > Ni. The maximum concentrations of Zn, Cu, Ni, Cd, and Pb in wheat grains were 3.20, 1.20, 0.52, 0.31, and 0.21 mg kg-1, respectively. The bioconcentration and translocation factors of wheat showed that heavy metals quantitatively accumulated in the roots and were poorly translocated to the grains. The potential health risks, calculated as hazard quotients (HQ), were less than unity for most heavy metals, indicating that local people are within the safe limit regarding non-carcinogenic risks. However, the HQ value of Cd exceeded 1 for both children and adults, indicating a high health hazard for the whole exposed population by this metal.

RETRACTED: Ecological risk assessment of coastal ecosystems: The case of mangrove forests in Hormozgan Province, Iran.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of at the request of the Editors-in-Chief. After a thorough investigation, the Editors have concluded that the acceptance of this article was partly based upon the positive advice of three illegitimate reviewer reports. The reports were submitted from email accounts which were provided by the corresponding author C.A. Damalas as suggested reviewers during the submission of the article. Although purportedly real reviewer accounts, the Editors have concluded that these were not of appropriate, independent reviewers. This manipulation of the peer-review process represents a clear violation of the fundamentals of peer review, our publishing policies, and publishing ethics standards. Apologies are offered to the reviewers whose identity was assumed and to the readers of the journal that this deception was not detected during the submission process.

RETRACTED: Public environmental awareness of water pollution from urban growth: The case of Zarjub and Goharrud rivers in Rasht, Iran.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editors-in-Chief. After a thorough investigation, the Editors have concluded that the acceptance of this article was based upon the positive advice of three illegitimate reviewer reports. The reports were submitted from email accounts which were provided by the corresponding author C.A. Damalas as suggested reviewers during the submission of the article. Although purportedly real reviewer accounts, the Editors have concluded that these were not of appropriate, independent reviewers. This manipulation of the peer-review process represents a clear violation of the fundamentals of peer review, our publishing policies, and publishing ethics standards. Apologies are offered to the reviewers whose identity was assumed and to the readers of the journal that this deception was not detected during the submission process.

Flavonoid and leaf gas exchange responses of Centella asiatica to acute gamma irradiation and carbon dioxide enrichment under controlled environment conditions.

The study was couducted to investigate the effects of gamma irradiation and CO2 on flavonoid content and leaf gas exchange in C.asiatica. For flavonoid determination, the design was a split split plot based on Randomized Complete Block Design (RCBD). For other parameters, the designs were split plots. Statistical tests revealed significant differences in flavonoid contents of Centella asiatica leaves between different growth stages and various CO2 treatments. CO2 400, G20 (400 = ambient CO2; G20 = Plants exposed to 20 Gy) showed 82.90% higher total flavonoid content (TFC) in the 5th week than CO2 400 as control at its best harvest time (4th week). Increasing the concentration of CO2 from 400 to 800 µmol/mol had significant effects on TFC and harvesting time. In fact, 800 µmol/mol resulted in 171.1% and 66.62% increases in TFC for control and irradiated plants, respectively. Moreover, increasing CO2 concentration reduced the harvesting time to three and four weeks for control and irradiated plants, respectively. Enhancing CO2 to 800 µmol/mol resulted in a 193.30% (CO2 800) increase in leaf biomass compared to 400 µmol/mol and 226.34% enhancement in irradiated plants (CO2 800, G20) [800 = Ambient CO2; G20 = Plants exposed to 20 Gy] than CO2 400, G20. In addition, the CO2 800, G20 had the highest amount of flavonoid*biomass in the 4th week. The results of this study indicated that all elevated CO2 treatments had higher PN than the ambient ones. The findings showed that when CO2 level increased from 400 to 800 µmol/mol, stomatal conductance, leaf intercellular CO2 and transpiration rate had the tendency to decrease. However, water use efficiency increased in response to elevated CO2 concentration. Returning to the findings of this study, it is now possible to state that the proposed method (combined CO2 and gamma irradiation) has the potential to increase the product value by reducing the time to harvest, increasing the yield per unit area via boosting photosynthesis capacity, as well as increasing biochemicals (flavonoids) per gram DM.

Effects of acute gamma irradiation on physiological traits and flavonoid accumulation of Centella asiatica.

In the present study, two accessions of Centella asiatica (CA03 and CA23) were subjected to gamma radiation to examine the response of these accessions in terms of survival rate, flavonoid contents, leaf gas exchange and leaf mass. Radiation Sensitivity Tests revealed that based on the survival rate, the LD(50) (gamma doses that killed 50% of the plantlets) of the plantlets were achieved at 60 Gy for CA03 and 40 Gy for CA23. The nodal segments were irradiated with gamma rays at does of 30 and 40 Gy for Centella asiatica accession 'CA03' and 20 and 30 Gy for accession 'CA23. The nodal segment response to the radiation was evaluated by recording the flavonoid content, leaf gas exchange and leaf biomass. The experiment was designed as RCBD with five replications. Results demonstrated that the irradiated plantlets exhibited greater total flavonoid contents (in eight weeks) significantly than the control where the control also exhibited the highest total flavonoid contents in the sixth week of growth; 2.64 ± 0.02 mg/g DW in CA03 and 8.94 ± 0.04 mg/g DW in CA23. The total flavonoid content was found to be highest after eight weeks of growth, and this, accordingly, stands as the best time for leaf harvest. Biochemical differentiation based on total flavonoid content revealed that irradiated plantlets in CA23 at 20 and 30 Gy after eight weeks contained the highest total flavonoid concentrations (16.827 ± 0.02; 16.837 ± 0.008 mg/g DW, respectively) whereas in CA03 exposed to 30 and 40 Gy was found to have the lowest total flavonid content (5.83 ± 0.11; 5.75 ± 0.03 mg/g DW). Based on the results gathered in this study, significant differences were found between irradiated accessions and control ones in relation to the leaf gas. The highest PN and gs were detected in CA23 as control followed by CA23 irradiated to 20Gy (CA23G20) and CA23G30 and the lowest PN and gs were observed in CA03 irradiated to 40Gy (CA03G40). Moreover, there were no significant differences in terms of PN and gs among the irradiated plants in each accession. The WUE of both irradiated accessions of Centella asiatica were reduced as compared with the control plants (p < 0.01) while Ci and E were enhanced. There were no significant differences in the gas exchange parameters among radiated plants in each accession. Moreover, malondialdehyde (MDA) of accessions after gamma treatments were significantly higher than the control, however, flavonoids which were higher concentration in irradiated plants can scavenge surplus free radicals. Therefore, the findings of this study have proven an efficient method of in vitro mutagenesis through gamma radiation based on the pharmaceutical demand to create economically superior mutants of C. asiatica. In other words, the results of this study suggest that gamma irradiation on C. asiatica can produce mutants of agricultural and economical importance.

Optimization of an efficient semi-solid culture protocol for sterilization and plant regeneration of Centella asiatica (L.) as a medicinal herb.

The present study investigates the effects of different concentrations, as well as type of plant growth regulators (PGRs) and medium (MS, Duchefa) on the growth and development of Centella asiatica in semi-solid culture. In addition, a protocol for successful sterilization of C.asiatica explants prepared from field-grown plants highly exposed to fungal and bacterial contamination was determined. Results for sterilization treatments revealed that applying HgCl2 and Plant Preservative Mixture (PPM) with cetrimide, bavistin and trimethoprim which were included after washing with tap water, followed by the addition of PPM in the medium, produced a very satisfactory result (clean culture 90 ± 1.33%) and TS5 (decon + cetrimide 1% + bavistin 150 mg/L + trimethoprim 50 mg/L + HgCl20.1% + PPM 2% soak and 2 mL/L in medium) was hence chosen as the best method of sterilization for C.asiatica. The synergistic combination of 6 benzylaminopurine (BAP) and 1-naphthaleneacetic acid (NAA) in concentrations of 2 mg/L and 0.1 mg/L, respectively, in Duchefa medium compared with MS induced the most optimal percentage of sprouted shoots (93 ± 0.667), number of shoots (5.2 ± 0.079) and nodes (4 ± 0.067) per explant, leaf per explant (14 ± 0.107) and shoot length (4.1 ± 0.67 cm). Furthermore, optimum rooting frequency (95.2 ± 0.81%), the number of roots/shoot (7.5 ± 0.107) and the mean root length (4.5 ± 0.133 cm) occurred for shoots that were cultured on full-strength MS medium containing 0.5 mg/L indole-3-butyric acid (IBA). In this study, the acclimatized plantlets were successfully established with almost 85% survival. The findings of this study have proven an efficient medium and PGR concentration for the mass propagation of C.asiatica. These findings would be useful in micropropagation and ex situ conservation of this plant.