Iranian Journal of Plant Physiology
Volume:10 Issue: 4, Summer 2020

Abstract Pesticides are agrochemical used to increase agronomic production and higher economic profit. However, these chemical pesticides could be persistent in soil and water, collective in silt or bio-aggregates in biota relying upon their dissolvability, prompting various kinds of natural contamination. These pesticides have also shown detrimental effects such as phytotoxicity, genotoxicity, and cytotoxicity on targets plant along with alteration in the antioxidant system. The demerits continue as they also affect non-target species such as humans, birds, animals, and other aquatic organisms. The higher accumulations of pesticides are also responsible for the generation of ROS that leads to oxidative stress and finally cell demise. Thus, in this review, the toxicity of pesticides will be discussed in detail at a cellular and molecular level linked with the response of the plant defense system. Besides this, various strategies that have been commonly used worldwide to remediate the toxicity have also been highlighted in the later section. The study will facilitate plant researcher and chemical engineer to understand the gap between the research and a novel, innovative and cost-effective technique/ procedure will be outlined for healthy environments

In this study, the efficiencies of seed priming with electromagnetic field (0, 2, 4, and 6 mT; 30 minutes daily for 3 days) were investigated in Salvia nemorosa. The exposure to electromagnetic filed led to significant increases in biomass accumulation (mean=53.6 %). Electromagnetic filed treatments significantly increased K, Ca, Mg, and Fe contents in leaves by mean 39.5 %. The electromagnetic filed treatments at all applied intensities increased both chlorophyll and carotenoid contents. Moreover, the electromagnetic filed- treated seedlings had significantly higher protein levels (mean=47 %) than the control. The applications of electromagnetic filed treatments induced peroxidase activities (mean=34.5 %) in leaves. However, these treatments reduced the activities of superoxide dismutase and catalase enzymes. The PAL activities in the electromagnetic filed-treated seedlings were higher by 61 % over the control. With a similar trend, the electromagnetic filed treatments promoted flavonoid accumulations. These results support this hypothesis that the application of the electromagnetic field may improve plant growth and secondary metabolism. Further studies, especially at molecular levels may help to elucidate the complicated involved mechanisms.

Carum copticum L. is a medicinal plant of the Apiaceae family with medicinal properties. In this study, the effects of UV-B radiation on the photosynthetic pigments and essential oils as well as phenols and anthocyanin of the seedling and callus of C. copticum were investigated under in vitro conditions. For this purpose, the experiment was set up in a completely randomized design, with three replicates per treatment. The seedlings and calli of Ajwain were categorized in two groups: the first group served as control and the second group was exposed to artificial UV-B radiation for 30 min at 15 days. The results indicated UV-B treatment reduced fresh weight about 34% and 27% compared with control in seedlings and calli respectively. The amount of chlorophyll a, b and total chlorophyll as well as carotenoids decreased about 36%, 42%, 38% and 14% in seedling and 24%,32%, 26% and 14% in callus of C. copticum respectively under UV stress. The lowest and highest amounts of flavonoids and anthocyanin were observed at UV-B treatment and untreated plants respectively. In addition, The UV-B stress changed the compounds of the essential oil both in the seedlings and the calli of C. copticum. Analysis of the essential oil constituents showed thymol and gamatherpinen, the main essential oil components of C. copticum, increased under UV-B radiation. While, p-cymene concentration decreased under UV treatment Therefore, C. copticum is useful for the in vitro production of pharmaceuticals and other beneficial substances by plant tissue culture techniques under UV-B treatment.

In order to investigate the effect of magnesium oxide (MgO) and iron oxide (Fe2O3) ‎nanoparticles (NPs) on physiological traits and the yield of sour tea (Hibiscus Sabdariffa L.), a ‎factorial experiment was conducted in a randomized complete block design (RCBD) with four ‎replications in 2018. MgO and Fe2O3 were used in concentrations of 0.01% and 0.03% as foliar ‎application. The results showed NPS improved chlorophyll (Chl) content and index. The ‎highest total chlorophyll was obtained in plants treated with 0.01% of MgO and 0.0.3% of ‎Fe2O3. Catalase (CAT) and peroxidase (POX) activities significantly increased with NPs, in ‎which all combined concentrations of NPs had greater enzymes activities compared to control. ‎The seed weight in plants treated with 0.03% of MgO and 0.01% of Fe2O3 was higher ‎compared to non-NPs treatment. The highest mucilage yield was found at 0.01% of MgO and ‎‎0.03% of Fe2O3. Total flavonoid content (TFC) in plants treated with 0.01% of MgO and ‎‎0.01% of Fe2O3 was higher than other experimental treatments. The treatment including 0.01% ‎of MgO and non Fe2O3 had lower anthocyanin content compared to other combined levels of ‎NPs. Carotenoid increased with medium concentrations of NPs, but decreased with high level ‎of NPs (0.03%). Protein concentration at 0.01% of MgO and 0.03% of Fe2O3 and 0.03% of ‎MgO and 0.01% of Fe2O3 was higher than other experimental treatments. According tour ‎results, we suggest the use of 0.01% of MgO and 0.03% of Fe2O3 for improving the ‎physiological properties of sour tea. ‎

This research was carried out to study the effect of TiO2 and nano-TiO2 on some chemical compounds in a medicinal plant Lallemantia iberica under water deficit conditions. The experiment was conducted as a factorial arrangement in a randomized complete block design with three replications. The first factor was the application of external materials as spraying with 3 levels of control, TiO2 and nano-TiO2, and the second factor was 100% (no stress), 75% (moderate stress) and 35% (severe stress) irrigation content. The results of measurements showed moderate stress and the use of nano-TiO2 caused a significant increase in phenolic content, total flavonoid and antioxidant activity; severe drought stress significantly reducing these compounds. The effect of nano-TiO2 on catalase and superoxide dismutase enzyme activity was also significant, and in the treatment of nano-TiO2 and moderate stress, the highest activity level of these two enzymes was observed. Identification of phenolic compounds of the extracts by HPLC indicated the production of vanillic, ferulic acid and syringic acid by nano-TiO2 spray application. Gallic acid was measurable in moderate and severe stress and caffeic acid in severe stress under the influence of nTiO2. The sinapic acid and syringic acid contents increased under moderate stress and severe stress decreased them. Finally, it is concluded that nano-TiO2 in comparison with TiO2 reduces the effects of drought stress on L. iberica and can be used to produce this plant in water-deficit areas.

The objective of this paper was to study the effects of two strains of isolated plant growth-promoting rhizobacteria (PGPR) on physiological and biochemical changes of wheat leaves under salinity conditions. The sterilized seeds were soaked in distilled water (control) and Nutrient Broth liquid medium of Enterobacter cloacae and Bacillus cereus (inoculated treatment) for 2 hours. After 10 days of growth, seedlings were selected for salinity stress treatments (0, 100, and 200 mM NaCl). After 10 days of starting salinity treatments, plants were harvested. Results showed that wheat plant growth, chlorophyll content and catalase activity were reduced under salinity condition; however PGPRs pre-treatments improved them under stress condition. Salinity significantly increased phenolic, carotenoids, proline and sugars content and peroxidase activity. Moreover, inoculation of seeds by PGPRs increased them under salinity. Lipid peroxidation increased but ascorbate peroxidase activity decreased as a response of saline stress and PGPRs pretreatment of seeds reduced them. Salinity increased sodium content, and PGPRs pretreatments decreased sodium absorption under salt stress. Moreover, in this study, Enterobacter cloacae inoculation of seeds increased wheat plants magnesium and potassium content in control condition as well as under salt stress. Data of experiment showed that the priming with PGPRs which tested in the present study especially E. cloacae can promote plant growth and salt tolerance.

To investigate the effects of irrigation intervals and humic acid application on some phophysiological and biochemical of thyme (Thymus vulgaris), the experimental in the form of factorial in the design complete randomized block in four replications at Miandoab University Research Field in 2019. Experimental treatments were at four levels of irrigation intervals (once every three days, once every six days, once every nine days and every day as control) and three levels of humic acid solution (zero, 200 and 400 mg l-1). The results showed that increasing irrigation intervals, significantly increased total phenol, antioxidant activity, proline and soluble sugars. Irrigation interval at highest level (once every nine days) compared to control increased proline, phenolic compounds, antioxidant activity, soluble sugars, essential oil and thymol by 58.79%, 47.27%, 21.25%, 62.57%, 66.67% and 19.24%, respectively. Increasing irrigation intervals, significantly reduced plant height, fresh and dry weight of plant. Application of humic acid had a significant positive effect on all studied traits. Also, interaction of irrigation intervals and humic acid application had significant effect on all traits except essential oil percentage, phenolic compounds and thymol. According to the results of this experiment, the application of 400 mg l-1 humic acid at irrigation interval of once every nine days is considered to be the best economically treatment because with less water consumption with humic acid application, this plant can achieve the same functions as consuming more water, especially this treatment caused a significant increase in effective substance of Thymus vulgaris.

In the last years, there is a growing demand for plants used in traditional medicine. Licorice (Glycyrrhiza glabra) contains different phytocompounds, that have demonstrated various pharmacological activities. The endophytic fungus, Piriformospora indica, has been reported to enhance the growth of host plants and allow them to survive under abiotic and biotic stress. This study was undertaken to investigate the effect of P. indica on drought stress tolerance of G. glabra. The experiment was conducted in a completely randomized design with three fungus treatments (spore, mycelium and non-inoculated), and two levels of drought treatments (Filed capacity and 50% F.C.) in three replications. Four weeks after stress induction (six weeks after inoculation), samples were collected and, growth and morpho-physiological traits were measured. The drought stress decreased shoot, and root dry weight, chlorophyll content, potassium, and phosphorus content and increased electrolyte leakage, H2O2, proline, and Na; but, the interaction of licorice with P. indica resulted in an overall increase in plant biomass. The photosynthetic pigment (Chl a, Chl b, total Chl, and carotenoid), proline, K, and P were significantly higher for inoculated seedling. Furthermore, the inoculated seedling had lower H2O2, electrolyte leakage, and Na content. In conclusion, our findings indicated that the symbiotic association of endophytic fungus P. indica had a positive effect on growth and morpho-physiological traits and also can help the plants to tolerate drought stress. These results are opening up a window of opportunity for application of this fungus in desert agriculture of medicinal plants.