Iranian Journal of Plant Physiology
Volume:5 Issue: 1, Autumn 2014

The roots and rhizomes of Valeriana (Valerianaofficinalis L.) are rich with valuable metabolites such as valerenic acid and valepotriates are used as mild sedatives. The aim of the present study was to investigatethe effect of four levels of calcium and potassium compounds (half, full, 2 and 4-fold) of normal Murashige and Skoog (MS) media including KI and CaCl2on ValerianaofficinalisL. hairy roots for scaling-up producing valerenic acid. Various explants of 42-day-old sterile seedlings derived from V. officinaliswere used for a genetic transformation viaAgrobacterium rhizogenesA13strain.Polymerase chain reaction (PCR) analysis and genes primers ofrolB and virDwere conducted to confirm the transgenic nature of the roots and that the roots were bacteria-free. Then,the hairy root cultures of V. officinaliswere maintained in the media for investigations of valerenic acid production ability. After 35 days the valerenic acid content in hairy roots was measured using high-performance liquid chromatography (HPLC) to determine the best yielding conditions.The highest valerenic acid (0.69±0.03 mg/g DW) accumulation was obtained from hairy roots culturedin2-fold of calcium media, which was1.92 times higher than normal culture (0.36± 0.01 mg/g DW). The results of this experiment also showed that application of double (880 mg/l) calcium in mediahad a positive effect on growth of transformed hairy roots.The results revealed that calcium concentration in the MS medium may be used for the intensification of the valerenic acid productionin Valerianaofficinalis hairy roots cultures.

The effects of salt stress and auxin on germination factors of three wheat cultivars viz. Sepahan, c-84-8, and c-83-1 were studied under controlled conditions. Germination was assessed using three replicates of 25 seeds in a factorial lay out in Completely Randomized Design (CRD) testing combinations of three levels of salinity (0, 4, and 8 dSm-1 NaCl) and three levels of auxin (0, 0.5, and 1 ppm IAA) on seeds of three wheat cultivars in 9 cm diameter Petri dishes. Results showed that increasing concentrations of NaCl reduced germination percentage, radicle length, plumule length, seedling fresh and dry weight, and plumule dry weight. Plumule dry weight increased in seeds only at 4 dSm-1. Auxin increased plumule length, seedling fresh and dry weight, and plumule dry weight, but did not influence seed germination percentage and radicle length. C-84-8 cultivar showed high seed germination percentage, radicle length, and plumule length in comparison to other cultivars while c-83-1 cultivar had high radicle dry weights and Sepahan cultivar produced high seedling fresh and dry weights.

Heavy metals are among soil pollutant resources that in case of accumulation in the soil and absorption by the plant, enter into the food chain and poison the plants or the people who consume those plants. This research was performed in order to examine the role of cadmium as a heavy metal in the activity of catalase and peroxidase as well as protein concentration in Trifolium resupinatum L. based on a randomized block design with three repetitions. The used treatments included consumption of Cd (NO3)2at four levels, namely, 0, 100, 200, and 300 ppm. The plants under study were treated for 10 days. The results of the study showed that catalase activity decreased by the increase of cadmium. Moreover, peroxidase activity increased by an increase inthe consumption of cadmium. The analysis of protein level showed that plantlet protein decreased in high cadmium concentrations. The findings also demonstrated that cadmium concentration in roots was higher than in shoots.

In order to evaluate the effects of priming materials and duration of priming on the seed physiological enhancement and biochemical traits of germination in pumpkin seeds a factorial experiment was conducted based on a completely randomized design with three replications at the University of Mohaghegh Ardabili. Treatments were priming with water, NaCl (3%), gibberellic acid (20 mg L-1), and ascorbic acid (20 ppm) for 8, 16, and 24 hours. Seed mass as a control for comparison of different pretreatment methods was measured. Results showed that priming treatments except gibberellin application, caused an increase in radicle length. Increase in priming duration increased the plumule length of seedlings. With increasing duration of priming, radicle length also increased except for seeds primed with NaCl. Seedlings from primed seeds with gibberellin had the highest dry weight (1.08 g) when compared to other priming treatments and control. Percentage and germination rate in the seeds primed with water, gibberellic acid, and ascorbic acid increased with increasing duration of priming and it was observed that the rate of increase was even higher in ascorbic acid treatment. Superoxide dismutase, catalase, and peroxidase in sodium chloride and gibberellic acid treatments had the highest and lowest activity, respectively. The activity of these enzymes had upward trend except in halo-priming, and hormone-priming with gibberellin for 24 h was the best treatment considering enzyme activity.

Soil salinity is one of the major abiotic stresses that adversely affect plant productivity and quality. Therefore, an experiment was conducted to investigate the effects of seed treatment with L-arginine on some morphological and physiological parameters of Brassica napus under salinity stress. The seeds of canola were pre-treated with three arginine concentrations (0, 5, and 10μM Arg) for 24 hours. Then they were subjected to three levels of salt treatments (0, 50, and 100 mMNaCl) for 7 days. Results of this experiment indicate that salinity stress caused a number of morphological and physiological changes in the canola plant, including decrease in root and shoot length. Hydrogen peroxide and malondialdehyde (MDA) content increased in leaves of canola plant under salt stress. Salt stress also induced changes in antioxidant enzymes activitiessuch as catalase (CAT), ascorbate peroxidase, (APX), and Guaiacol peroxidase (GPX). In conclusion, the adverse effects of salt stress on canola can be alleviated by the arginine pre-treatment through modulating activities of antioxidant enzymes.

The growth of medicinal plants and biosynthesis of secondary metabolites is influenced by plant growth regulators. In this study we investigated influence offour levels (0, 500, 1000, and 1500 mg l-1) of2-chloroethyltrimethylammonium chloride (Cycocel), a plant growth retardant, on growth parameters and some biochemical parameters of cannabis plants. Cycocel only at 500 mg l-1 decreased shoot length of male plants. The fresh weight of leaves in female plants decreased with 1500 mg l-1Cycocel. The other Cycocel treatments increased the fresh weight of leaves in female and male plants. Root and stem fresh weight of male and female plants showed an increase in most treatments (except for 1500 mg l-1Cycocel). Cycocel at 1000 mg l-1 had enhancing effect on the fresh weight of male and female flowers. Also, the plants treated with Cycocel had a higher content of soluble carbohydrates and protein. Malondialdehyde content was decreased in male and female plants by 500 mg l-1Cycocel treatment. Tetrahydrocannabinol (THC) content increased in male plant leaves under 1000 and 1500 mg l-1Cycocel treatment, but in female plants only 500 mg l-1Cycocel caused an increase in THC content in leaves. While Cycocel decreased cannabidiol (CBD) content in male leaves, in female leaves it increased CBD concentration. In fact, only 500 mg l-1Cycocelled to more CBD content in female flowers while the other treatments declined CBD content in female flowers. The findings showed that the response to Cycocel depended on the sex in cannabis plants. Ineffectiveness of Cycocel in reducing shoot length suggests that cannabis is insensitive to Cycocel as an inhibitor of gibberellin biosynthesis and its application at specific concentrations can be used to improve growth.

This experiment was carried out to study the effect of humic acid and growth promoting bacteria on uptake of cadmium heavy metal by annual alfalfa (Medicago scutellata L.). The experiment was arranged in pot experiment conditions in Isfahan, Iran in 2011. A factorial design was used based on completely randomized block design with four replications. Experimental treatments were humic acid and growth promoting bacteria. Biofertilizers used in the experiment were bacterial species Azotobacter chroococcum, Azospirillum lipoferum, and Pseudomonas putida in a mixture form and Glomus intraradices was used as mycorrhiza fungi. Cadmium heavy metal was applied at 0, 40, and 80 mg kg-1 soil cadmium chloride (CdCl2) levels. Root and shoot cadmium concentrations and translocation factor were measured in the plants under study. The results suggested that there were significant differences between treatment levels and their interactions for all measured characteristics. A significant trend in cadmium accumulation in root and shoot organs were observed with increasing in the cadmium concentration.

This experiment was carried out to study the effect of humic acid and growth promoting bacteria on uptake of cadmium heavy metal by annual alfalfa (Medicago scutellata L.). The experiment was arranged in pot experiment conditions in Isfahan, Iran in 2011. A factorial design was used based on completely randomized block design with four replications. Experimental treatments were humic acid and growth promoting bacteria. Biofertilizers used in the experiment were bacterial species Azotobacter chroococcum, Azospirillum lipoferum, and Pseudomonas putida in a mixture form and Glomus intraradices was used as mycorrhiza fungi. Cadmium heavy metal was applied at 0, 40, and 80 mg kg-1 soil cadmium chloride (CdCl2) levels. Root and shoot cadmium concentrations and translocation factor were measured in the plants under study. The results suggested that there were significant differences between treatment levels and their interactions for all measured characteristics. A significant trend in cadmium accumulation in root and shoot organs were observed with increasing in the cadmium concentration.