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Aims The secondary metabolites of plants have been considered due to their diversity and roles in plants and human health. Grapevine is one of the plants that have secondary compounds with medicinal properties. such compounds include resveratrol which is a phenolic compound from the stilbenoid group. In order to investigate the resveratrol production under the effect of an elicitor, a CRD design with four replications using Soltani cultivar was done.
Materials & Methods. The salicylic acid (SA) was used as an elicitor with variable concentrations including 0, 10^-4, 10^-5, 10^-6 and was introduced into MS medium without hormones to examine it`s stress effects. At the molecular level, the effect of SA on the expression of stilbene-synthase gene was evaluated by semi-quantitative RT-PCR. In the biochemical experiment, the rate of resveratrol production was measured by HPLC.
Findings Stilbene-synthase expression analysis showed that SA with a concentration of 10^-4 M had a positive and incremental effect on gene expression and showed a 35.48% of increase compared to the control state, and also the concentration of 10^-5 M increased the gene expression 5.65% in relation with control state. In the biochemical experiment, increasing in production of resveratrol was observed in 10^-4 M treatment compared to the control treatment (6.1 µg) and 10^-5 M treatment (3.25 µg) did not show a significant difference with the control sample.
Conclusion SA as an elicitor and stimulant of resveratrol production could enhance the expression of stilbene-synthase gene followed by enhancing the medicinal properties of the Vitis plant.

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Effects of yeast extract (YE) (0, 0.05, 0.1, 0.2, 0.5 and 1%) were investigated on rosmarinic acid (RA) accumulation and tyrosine aminotransferase (TAT) gene expression in Melissa officinalis seedlings at different time intervals (4 and 17 hours). Based on the results, only YE concentrations of 0.05%, 0.1%, and 0.2%, for the 17-hour treatment, significantly stimulated RA biosynthesis pathway. At this elicitation time, flavonoid content and TAT gene expression significantly increased by the increase in YE concentration up to 0.2% as compared to the control. The maximum amount for both of them was seen at 0.1% YE treatment, where the RA accumulation was drastically elevated. Furthermore, the aerial parts were improved when root lengths were decreased; this was observed in seedlings that were treated by YE for 30 days. Overall, these observations can be attributed to the oxidative stress induced by YE, as a consequence of its uptake by the plant, as revealed by increasing activities in superoxide dismutase and catalase.

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The flavonoid and phenolic compounds are among the main pharmaceutical components of medicinal plants. These compounds are considered as effective anti-oxidant sources. Five cyanobacterial extracts were used to stimulate the plant growth and increase production of specific secondary metabolites in Plantago major as a medicinal plant. These cyanobacteria were isolated from the growth bed of the plant in its natural habitats. Nitrate-free BG11 medium was used for preparing axenic monoalgal cultures. Pot experiments were performed by spraying cyanobacterial extracts on the soil of treated plants every 20 days from the time of planting. Growth of plants was evaluated by measuring growth parameters such as plant height, root length, dry and fresh weight of plant, leaf number, leaf area, as well as inflorescence characteristics 60 days after planting. In addition to growth factors, the total amount of phenol and flavonoid of plants was also assessed. Statistical analysis showed that there was a significant difference in the vegetative and reproductive characteristics compared to the control plants. Also, the methanolic extraction of treated and control plants displayed the highest total phenolic and flavonoid content 77.23±3.21 µg of GA mg^-1 and 389.67±34.43 µg of RU mg^-1 in plants treated with Cylindrospermum michailovskoence. Based on the obtained results, cyanobacterial fertilizers are suggested as the biological elicitors to improve the quantity and quality of medicinal plants products. As a result of this study, chemical content of cyanobacterial extracts and the production of plant growth stimulating substances such as phytohormones can be proposed as factors affecting plant growth parameters and metabolites production.
 

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Digitoxin is a glycoside isolated from leaves of various species of Digitalis genus that are commonly called foxgloves. Digitoxin is used for chronic cardiac insufficiency, tachyarrhythmia form of atrial fibrillation, paroxysmal ciliary arrhythmia, and paroxysmal supraventricular tachycardia. 1-Deoxy-d-Xylulose 5-phosphate Reductoisomerase (DXR) is an important rate-limiting enzyme in 2-C-Methyl-d-Erythritol 4-Phosphate (MEP) pathway, and expression level of DXR plays a critical role in control of plant isoprenoid biosynthesis pathway. The effects of different elicitors including putrescine, spermine, and spermidine at concentrations of 50 and 100 mg L^-1 and also Methyl Jasmonate (MJ) at 50, 100, and 200 μM concentrations were explored on transcript levels of DXR gene in cell suspension culture of foxglove (Digitalis purpurea). DXR transcription levels were assessed by the semi-quantitative RT-PCR. Results showed that elicitors had significant effects on the expression level of DXR and contents of cardenolide and digitoxin. The highest digitoxin (61.3 μg g^-1 DW) and cardenolide (1.48% mg^-1 DW) content was observed in 100 mg L^-1 spermidine treatment. In all treatments, the expression of DXR gene was increased compared with the control sample. The highest transcription levels of DXR gene was observed in 50 μM MJ and 100 mg L^-1 putrescine elicitors, which was nine folds higher than the control condition, and the lowest levels were observed for putrescine treatments at concentrations of 50 and 100 mg L^-1, respectively.