فصلنامه فرآیند و کارکرد گیاهی
سال هشتم شماره 3 (پیاپی 31، Aug and Sep 2019)

In the present study, the effect of exogenous silver nitrate (Ag+) and copper sulfate (Cu2+) applications on production of artemisinin and phenolic compounds as well as oxidative stress in the shoot cultures of Artemisia annua was investigated. A significant decrease in the shoot biomass and the total chlorophyll was observed in the shoots exposed to increased Ag concentration. Additionally, a significant increase in the carotenoid content was evident in the shoots (1.5 fold). The shoots exposed to Cu exhibited a marked increment in the biomass (1.5 fold), the total chlorophyll (2.2 fold) and the carotenoid content (1.4 fold). Ag and Cu induced generation of H2O2, LOX activity and increased production of MDA via both enzymatic and non-enzymatic peroxidation of membrane lipids one week after elicitation. In this study, we found that Ag and Cu markedly induced GST activity at the concentrations as low as 100 µM Ag and 25 µM Cu. Furthermore, Ag and Cu elicited accumulation of phenolic compounds (maximum value: 6.5 mg/gfw) and phenylalanine ammonia-lyase activity (2.5 folds). Artemisinin content was increased in the shoot cultures supplemented only with 5 µM of CuSO4 (0.65%). It was revealed that both Cu and Ag affected the phenolic compounds biosynthesis in the shoot cultures of Artemisia. However, artemisinin production was only affected by Cu.

The Fig (Ficus carica.L) is a woody perennial crop, cultivated worldwide in subtropical regions. Since, salinity is the main concern of fig industry, therefore, studying the pattern of ion absorption and accumulation contribute during the stress in different plant organs can lead understanding the mechanism of tolerance/sensitivity. So, during 2016-2017, seven fig cultivars (‘Sabzʼ, ‘Siyahʼ, ‘Shah Anjirʼ, ‘Atabakiʼ, ‘Kashkiʼ, ‘Matiʼ and ‘Barʼ) were subjected to saline water (0.5, 2, 4, 6, 8 and 10 dSm-1). Then, ions accumulation of different organs, leaf abscission, dry matter, relative water content, and photosynthetic indices were compared to introduce the most salt-tolerant cultivar. The results indicated salinity caused a decrease in leaf relative water content, photosynthesis rate, K content and an increase in leaf abscission, Cl and Na content. Principal component analysis of the data led to a reduction in the variables with major contributions from the content of K, Na and Na/K of leaf and root, shoot Na, leaf Cl, and RWC. The ‘Siyahʼ and ‘Sabzʼ, as the most salt-tolerant cultivars, had the maximum leaf abscission, the least Na content and the maximum shoot dry matter under salt condition. The ‘Shah Anjirʼ, as the most salt-sensitive cultivar, could not restrict root Cl ex-flux into shoot and leaf.

D. kotschyi is a source of essential oils with medicinal properties such as antihyperlipidemic, immunomodulatory, antinociceptive and cytotoxic effects. This study aimed to investigate whether the application of chitosan can improve plant growth, increase secondary metabolite production and help antioxidant enzymatic systems in Dracocephalum kotschyi under in vitro culture. Tow-week-old seedlings of D. kotschyi were cultured in MS medium containing 0, 5, 10 and 20 mg.L-1 chitosan. Four weeks after treatments, the enzymatic and morphological parameters were measured and the GC/MS analysis was used to evaluate the secondary metabolites. Chitosan resulted in changes in physiological and morphological responses. It had a beneficial effect on the main essential oil contents such as thymol, p-cymene and candinol increased by 16.2%, 20.3% and 34%, respectively. In spite of reduction of antioxidant  activities and growth, 20 mg/l had a positive effect on the oil components in D. Kotschyi.

Salicylic acid can mitigate the impacts of salinity and drought stresses in crops. To study the effect of salicylic acid under iso-osmotic drought and salt stresses on nutrients absorption and growth of linseed (Linum usitatissimum L.), an experiment was conducted based on a completely randomized design with three replications in Yasouj University in 2016. Treatments included salinity and drought with similar osmotic potentials (-2, -4, -7 and -9 bar) in 8 levels and control that applied in Hoagland solution. The second factor was salicylic acid (0 and 0.5 mM). Salinity and drought applied using sodium chloride and polyethylene glycol 6000, respectively. The results showed that root and shoot dry weight and Fe, Zn, Mn and Ca content decreased by increasing salinity and drought compared to control, however salicylic acid application significantly increased these traits, especially under salinity conditions. Na content of Shoot significantly raised by increasing salinity compared to control and salicylic acid decreased it. Drought, and also salicylic acid, had no significant effect on shoot and root Na. Shoot and root dry weights were more significantly affected by drought than salinity in mild stress levels, but the effect of drought and salinity were the same at high levels. Generally it found that the negative effects of drought were more destructive than salinity at lower osmotic potentials but at higher osmotic potentials impact of drought and salinity was the same indicating the ionic toxicity of salinity at high Na stress. Salicylic acid significantly mitigated the negative impacts of osmotic stress especially under salinity conditions.

One of the most effective micronutrients on the quantity and quality of medicinal herbs is zinc (Zn). The present study aimed to assess the impact of the foliar application of various Zn sources (0.2% w/v) including Zn chelated by amino acid (ZnAAC), Zn-sulfate and Zn-EDTA on qualitative and quantitative features of Lemon verbena (Lippia citriodora L.). In two harvests, the field experiment was performed in a randomized complete block design with three replications. Foliar application of treatments was conducted three times with one-month interval. Based on the findings, it was indicated that ZnAAC treatment has the highest effect on quantitative and qualitative characteristics of lemon verbena in comparison with other treatments. The maximum chlorophyll concentration, leaf area, leaf dry weight, essential oil content, and total antioxidant capacity (TAC) in both harvests were found in ZnAAC treatment. It is also indicated that Zn-sulfate was more effective compared to ZnEDTA in studied characteristics. It demonstrated that regardless of the source of applied Zn, all Zn application had a significant impact on all features in comparison with control. The analysis indicated that citral (10.4-20.2), geranial (11.4-23.2), neral (7.93-18.6), runs-Caryophyllene (2.34-3.22) and 1,8-cineol (1.01-1.35) were the predominant compounds in the essential oil in both harvests. The highest and lowest amounts of geranial, neral, and citral in both harvests were measured in ZnAAC (56.81%) and ZnEDTA (48.05%) treatments, respectively. Based on the findings, it seems that using ZnAAC can enhance the quantitative and qualitative characteristics of the lemon verbena.

Teucrium chamaedrys is regarded as an herbaceous perennial plant from Lamiaceae family that is used as medicinal plants and food from ancient times. Due to the recent developments in tissue culture techniques and extraction of secondary metabolites, this study aimed to investigate the explants of the Teucrium for callus induction and secondary metabolites. The interaction of Auxin hormones including 2,4-dichlorophenoxy acetic acid (2,4-D) and naphthalene acetic acid (NAA) with cytokinin hormones including benzyl amino purine (BAP) or kinetin (KIN) was used as hormonal treatments for callus induction. At the second stage, the presence of secondary metabolites in the NAA/KIN, NAA/BAP and 2,4-D/KIN -treated callus were investigated. Finally, regeneration process from the callus tissue using different hormonal combinations was performed. Our results indicated that NAA/KIN (0.5:0.5mg/L) was the best hormonal combination for callus formation . On the other hand, The obtained calli were subjected to hydrodistillation for essential oil isolation. Chemical composition of the obtained oil was analysis using GC-MS apparatus. The results showed the presence of hexanone, oxalic acid, oxime, dodecane, tetratriacontane, dotriacontane, nonadecene, neophytadine, tetradecanol, dodecane and kalaren as main callus essential oil components. Regeneration process took place in NAA/BAP (0.1:0.5 mg/l) and NAA/KIN (0.5:0.5 mg/l) for shoot and root formation, respectively.

The objective of this study was to determine the effects of lead (Pb) exposure on bioaccumulation, growth, and tolerance mechanisms in summer savory (Satureja hortensis L.). Plants were subjected to different levels of Pb concentrations including 0 (control), 5, 10, 25, 50 and 100 mg L-1 in growing medium. Pb treatment led to significant increase in root and shoot Pb content. Calculation of BF, TF and TC revealed that Pb preferably accumulated in roots of S. hortensis and root to shoot transport was effectively restricted. Pb toxicity negatively affected plant growth as indicated by significant decrease in plant dry weight as well as roots and shoot length. Pb stress resulted in significant decrease in chlorophyll-a, chlorophyll-b and total chlorophyll content, whereas proline, soluble and reducing carbohydrates and anthocyanin content significantly increased as a result of Pb exposure. Specific activity of antioxidant enzymes including catalase and ascorbate peroxidase continuously increased as concentration of Pb in growing medium elevated. Based on our findings, due to high potential for Pb accumulation in root, S. hortensis may offer a feasible tool for phytostabilization purposes in mildly Pb contaminated soils.

For investigating the effect of vermicompost (VC) on improving phytoremediation of Pb by sunflower (Helianthus annuus) cultivar Lakumka, a factorial experiment was conducted in the pots containing soil or its mixture with 10% VC, in a greenhouse with controlled condition at 2018. After 3 weeks irrigation with normal water, plants were daily irrigated with high Pb-polluted water (0, 1000, 1500 or 2000 mg L-1) up to 3 more weeks. Then, changes in plant biomass, Pb accumulation in root and shoot, and absorption of some mineral nutrients were measured. Results showed that the shoot biomass of sunflower was not affected by Pb treatments. Pb accumulation in root was increased in a dose dependent manner, where in plants under 2000 mg L-1 it reached to 31 times more than that of control. This increase was reinforced by VC so that in Pb+VC-treated plants the bioconcentration factor (BCF) of Pb in roots was higher than those not-amended with VC. However, both plant groups had a good BCF much more than 1.  Pb accumulation in leaves of Pb-treated plants showed a significant increase, where VC caused a significant decrease in its accumulation. Effect of VC and Pb treatments on calcium, magnesium and zinc concentration of root and leaf did not follow the regular changes. Overall, sunflower cultivar Lakumka was an appropriate accumulator of Pb. VC can improve Pb phytoremediation by sunflower.

Soil pollution by oil compounds is one of the most common environmental problems. To study the effect of four different treatments of soil diesel pollution and diesel degrading bacteria (control, diesel, one bacterium and three bacteria) on some growth and biochemical factors of two cultivars of Zea mays (704 and 640) a factorial research was undertaken in the form of a completely randomized design with four replications in 2014. In addition, microbial parameters and gas chromatography analysis of plant and soil samples were performed. The results showed that in the presence of diesel contamination, dry weight (83%), leaf area (61%), chlorophyll content (71%) and relative water content (17%) of both cultivars decreased in comparing to the control plants. In all treatments, the amount of malondialdehyde (50%), flavonoids (70%), catalase enzyme (83%) and EC (35%) increased in comparing to the control. According to the results of GC analysis, the highest degradation of diesel oil in soil was related to the consortium bacteria. Researches have indicated that collaboration between plant and bacteria can speed up the removal of oil pollution from the soil.