Coordinated Effect of Ascorbate Biosynthesis and Recycling in Maize Seed Germination and Seedling Establishment under Low Temperature

The impacts of low temperature occasionally encountered at higher latitude regions on maize seed germination present significant threats to yield and cultivation. Exploring the association of antioxidant system with low temperature (LT) germination could support the breeding strategies for better responding to LT disturbance. In this study, we have examined the germination rate and growth potential of a set of elite maize inbred accessions under LT and normal temperature (NT) conditions in the field. These accessions were found to have variable germination rate and growth potential when grown at LT, whereas the difference is not significant under NT. Physiological study revealed lower hydrogen peroxide content in LT tolerant accessions when compared with sensitive ones. LT-tolerant and LT-sensitive lines maintained similar content of ascorbate (AsA) and glutathione (GSH), whereas the reduced substrate content of which were significantly higher in LT-tolerant accessions. Consistently, activities of ascorbate peroxidase and dehydroascorbate reductase, the enzyme components that responsible for the AsA-GSH recycling, were much higher in LT-tolerant lines. Transcription profile revealed the increased expression of ZmVTC2 gene in LT-tolerant inbred line, which was rate limited step in AsA biosynthesis. These data indicates that the coordinated improvement of AsA biosynthesis and AsA-GSH recycling increase the pool size of the total antioxidants, which ameliorate LT-induced oxidative stress during maize seed germination.

Nutrient status, hydrogen peroxide content and peroxidase activity of arbuscular mycorrhizal plants of Melilotus albus grown in diesel-contaminated substrate

Background: Petroleum hydrocarbons affect plant growth, but little is known about physiological responses of mycorrhizal plants facing diesel contamination. Objective: To evaluate the effects of arbuscular mycorrhizal fungi (AMF) on the nutritional status, peroxidase activity (POX), and hydrogen peroxide content (H2O2) in leaves of Melilotus albus planted under diesel-contaminated sand (7500 mg kg-1). Methods: A 2x2 factorial experiment was set in a completely randomized design, under greenhouse conditions for 35 days. Seedlings were pre-inoculated with AMF and transplanted to sand with or without diesel, including non-AMF plants. Results and conclusions: Diesel contamination impaired plant growth; AMF plants had similar growth than non-AMF plants at diesel-contamination, but low nutrient content. Protein content decreased due to diesel in non-AMF plants, but this content was low in AMF plants regardless diesel contamination. Diesel increased POX; whereas AMF plants with or without diesel had higher POX than non-AMF plants. The H2O2 content in AMF plants with or without diesel was low than non-AMF plants. Diesel contamination diminished AMF-colonization, but AMF dissipate more diesel hydrocarbons (>40%). Overall, AMF alleviated the toxic effects of diesel on plants.

Morphological, biochemical and molecular hallmarks of programmed cell death in stigmatic papillae of Brassica oleracea L.

The aim of this study is to determine the programmed cell death hallmarks in the stigmatic papillae of Brassica oleracea L. The flower development was divided in two main stages; pre-anthesis and post-anthesis. Programmed cell death hallmarks were examined in parallel to these stages. At pre-anthesis, the stigmatic papillae were ovoid and their dense cytoplasm were rich in insoluble polysaccharide and protein. At post-anthesis, vacuolization and enlargement were quite evident in papillae. Besides, the protein content decreased, but reactive oxygen species increased in comparison to the pre-anthesis stage. Although no significant change in superoxide dismutase activity was detected, catalase activity decreased and hydrogen peroxide content increased at post-anthesis. DAPI stained nuclei appeared rounded and smooth appearance at pre-anthesis, however, some invaginations and fragmentation in nuclei were observed at post-anthesis. Although, TUNEL staining was negative at pre-anthesis, while TUNEL positive reaction was significant in the nuclei of papillae at post-anthesis. In comparison to the pre-anthesis, the number of fragmented nuclei monitored by DAPI and TUNEL staining increased at post-anthesis.

Electromagnetic Field Improved Nanoparticle Impact on Antioxidant Activity and Secondary Metabolite Production in Anthemis gilanica Seedlings

Electromagnetic field (EMF) causes fundamental alternations in biological systems. In this study, we studied the effects of EMF on physiological responses and secondary metabolites production in SiO2 NP-treated Anthemis gilanica plants. The results indicated that EMF improved plant growth by inducing chlorophyll and carotenoid content, which led to enhanced biomass in SiO2 NP-treated plants. EMF enhanced adventitious roots in SiO2 NP-treated plants. EMF treatment improved the activity of antioxidative enzymes such as superoxide dismutase, catalase, and peroxidase in both control and SiO2 NP-treated plants. EMF and SiO2 NP treatments significantly declined hydrogen peroxide content in A. gilanica plants. Although protein content was reduced by SiO2 NP treatment, combined application of EMF with SiO2 NP caused a significant induction in protein content. Our results presented that EMF induced secondary metabolites accumulation such as flavonoid and phenol in SiO2 NP-treated A. gilanica plants. This work can open prospects for the production of the pharmaceutically high-value secondary metabolites.

Chitosan-Induced Activation of the Antioxidant Defense System Counteracts the Adverse Effects of Salinity in Durum Wheat

The present study was carried out with the aim of (i) evaluating the effect of chitosan (CTS) on the growth of durum wheat under salinity and (ii) examining CTS-regulated mechanisms of salinity tolerance associated with the antioxidant defense system. To achieve these goals, durum wheat seedlings were treated with CTS at different molecular weight, low (L-CTS, 50–190 kDa), medium (M-CTS, 190–310 kDa) and high (H-CTS, 310–375 kDa). The results obtained show that exposure to 200 mM NaCl reduced the shoot and the root dried biomass by 38% and 59%, respectively. The growth impairment induced by salinity was strongly correlated with an increase in the superoxide anion production (5-fold), hydrogen peroxide content (2-fold) and malondialdehyde (MDA) content (4-fold). Seedlings responded to the oxidative stress triggered by salinity with an increase in the total phenolic content (TPC), total flavonoid content (TFC) and total antioxidant activity (TAA) by 67%, 51% and 32%, respectively. A salt-induced increase in the activity of the antioxidant enzymes superoxide dismutase and catalase (CAT) of 89% and 86%, respectively, was also observed. Treatment of salt-stressed seedlings with exogenous CTS significantly promoted seedling growth, with the strongest effects observed for L-CTS and M-CTS, which increased the shoot biomass of stressed seedlings by 32% and 44%, respectively, whereas the root dried biomass increased by 87% and 64%, respectively. L-CTS and M-CTS treatments also decreased the superoxide anion production (57% and 59%, respectively), the hydrogen peroxide content (35% and 38%, respectively) and the MDA content (48% and 56%, respectively) and increased the TPC (23% and 14%, respectively), the TFC (19% and 10%, respectively), the TAA (up to 10% and 7%, respectively) and the CAT activity (29% and 20%, respectively). Overall, our findings indicate that CTS exerts its protective role against the oxidative damages induced by salinity by enhancing the antioxidant defense system. L-CTS and M-CTS were the most effective in alleviating the adverse effect of NaCl, thus demonstrating that the CTS action is strictly related to its molecular weight.

Estimativa da produção de etanol a partir de biomassas lignocelulósicas pré-tratadas com peróxido de hidrogênio

The objective of this work was to compare pre-treatments with hydrogen peroxide at 1 and 2% (v/v) and pH at 11.5 used in elephant-grass (EC), mulatto-grass (HD364) lignocellulosic biomass, bark of rice (CA) and leaves of the pineapple (AB) plant to estimate the production of second-generation ethanol (2G). The experimental design was completely randomized in a 4x2 factorial scheme with four replicates per treatment. Enzymatic hydrolysis was performed with the pretreated biomasses using Cellic/CTec2 enzyme. 7 ml of the hydrolyzed material and 0.14 g of non-isolated Saccharomyces cerevisiae yeast were used. After this dilution the material was taken to a styrofoam oven and measured at the temperature and volume of the gas produced at the time of 0,04; 0,08; 0,2; 0,63; 0,92; 1,19; 1,93; 2,19; 2,82; 3,15; 3,94 hours post-incubation. The results showed that the observed differences between the pretreatments influenced the yield in 2G ethanol differently between the biomasses, being the CE that presented the best yield, however, when evaluating the yield by the peroxide content within each biomass, both AB and EC showed no differences between pre-treatments. HD364 had better yield with 1% peroxide and CA with 2% peroxide.

Assessment of the response reactions of tomatoes depending on the phytosanitary status in condition of infection with viral agents

Relevance. Oxidative reactions (based on peroxidase activity, POX and polyphenol oxidase, PPO; hydrogen peroxide content) that occur in response to infection or reinfection of the off-spring of infected plants depend on the type of host-virus interaction (sensitive, tolerant, stable) and the nature of the interaction with viral infection (primary infection, reinfection of second and third generations).Results. Reinfection with tomato aspermy virus (TАV) or tobacco mosaic virus (TMV) of the off-spring of third infected tomato generation caused a significant decrease in POX activity compared to successive generations of infected plants (G2) for Craigella (Tm-22/Tm- 22) and S. pimpinellifolium genotypes or an increase for Rufina and Craigella (Tm-1/Tm-1) ones. In genotypes containing resistance genes, Rufina and Craigella, no differences were observed in PPO of TMV primary infection and control, while significant differences were found in case of TAV (susceptibility). As a result of TMV infection, the sensitive (Elvira) and tolerant (S. pimpinellifolium) genotypes showed an increase in PPO values compared to the control. At the same time, in most genotypes primarily / secondarily infected with TAV or TMV, statistically significant differences were revealed in the activity of POX or PPO, as well as the accumulation of hydrogen peroxide in plant leaves, which indicates specific protective reactions of the genotypes.

Effect of Cucumber Mosaic Virus on Proline and Hydrogen Peroxide Content in Some Pepper Hybrids Grown in Lattakia Governorate, Syria

Al-Ajouriyeh, H., I. Ismail, B. Samra and F. Sahyouni. 2021. Effect of Cucumber Mosaic Virus on Proline and Hydrogen Peroxide Content in Some Pepper Hybrids Grown in Lattakia Governorate, Syria. Arab Journal of Plant Protection, 39(1): 39-46. A study was conducted at Al-Muturki village in Lattakia Governorate during 2019/2020 growing season to investigate the effect Cucumber mosaic virus (CMV) infection on the proline and hydrogen peroxide (H2O2) content of four pepper hybrids (Taline F1, Amani F1, Harek F1 and Marvilo F1) at three periods post viral inoculation (15, 30 and 45 days). The experiment was carried out by using complete randomized block design with 8 treatments and 8 replicates per treatment. The results showed that the viral infection affected the proline and hydrogen peroxidase content 15 days after virus inoculation. The highest effect of the viral infection was at 30 days after virus inoculation, where the values of proline and hydrogen peroxidase of the infected pepper hybrids significantly increased compared to control plants. However, 45 days after virus inoculation, the effect of viral infection decreased with plant age. Keywords: Pepper, Cucumber mosaic virus, proline, hydrogen peroxidase.

Stability of electrolyzed water: from the perspective of food industry

Green cleaner and disinfectant can provide a better environment and they can reduce cleaning cost by eliminating the cost of harsh cleaning chemicals, minimizing cleaning chemicals storage space, reducing cost for wastewater treatment and reducing logistics cost for chemical supply. This study explored the personal view of Small and Medium Enterprises (SMEs) top to bottom workers towards the challenges during cleaning and disinfection process and their readiness in accepting a green cleaner and disinfectant. In this work, the advantages and disadvantages of electrolyzed water (EW) as green cleaner and disinfectant were discussed. A lab-scale batch ion-exchange membrane electrolysis unit was used to produce acidic electrolyzed water (AcEW) and alkaline electrolyzed water (AlEW). The stability of AcEW and AlEW was also studied based on its physical changes (pH, oxidative-reduction potential (ORP), chlorine content and hydrogen peroxide content) in 7 days of storage, whereby measurements were taken daily. The pH maintained for both AcEW and AlEW during the 7 days of storage. The ORP maintained at plateau for the first 5 days of AcEW storage. After 5 days, AcEW showed a decreasing trend. While ORP for AlEW increases drastically between day 1 and 2. Then, the ORP reaches a plateau after three days. The amount of free chlorine, total chlorine and hydrogen peroxide content was 10 mg/L, respectively, on the day of production. However, all the properties decreased gradually and there were no chlorine and hydrogen peroxide detected on the 7th day. The results from this study can be used as a guideline to store the EW and to understand the stability of the EW, which can benefit the SME food manufacturers.