Journal of Cell and Molecular Research

61-66

Authors: Nasrin Moshtaghi, Robab Ghahremanzadeh and Seyyed Hasan Marashi

Saffron (Crocus sativus L.) is an indigenous and the most valuable and marginal plant in Iran. However, limited knowledge exists on its molecular biology. The importance of this plant is due to the color, flavor and medicinal properties of its red stigmas. Saffron stigmas contain a high amount of carotenoids such as crocetin and crocin. Two genes, bch and pds, have essential role in carotenoid production. In this study, the effect of four different irrigation regimes was evaluated on the expression of bch and pds genes. Semi-quantitative RT-PCR showed no significant difference in the expression levels of genes of interest related to the internal standard (18S rRNA). Results of Real-Time PCR assays showed that the expression of bch and pds genes were affected by irrigation treatments as their expression decreased in irrigated plants in comparison to non irrigated ones, exept for one irrigation treatment (one irrigation in September) where the pds gene expression showed higher level. However, the expression profile of the genes was almost the same in all treatments. The comparison between results of two techniques indicated that the Real-Time PCR is more accurate for determination of the level of transcript in the Iranian saffron. It was interesting that by decreasing of irrigation, the expression level of these two genes increased indicating that abiotic stress and drought can affect on the gene expression relating to the saffron color.

74-80

Authors: Behrokh Shojaie, Ali Akbar Ehsanpour* and Mohammad Reza Abdi

In this study, the effects of gamma rays on changes of proline, sodium and potassium in potato calli (Solanum tuberosoum L.) cultivar "White Desiree" were investigated. After irradiation of calli by 60 and 80 Gy of gamma radiation, irradiated and non irradiated calli were transferred to a callus production medium containing 0, 30, 60, 90, 120 and 150 mM NaCl. After 26 days post treatment amounts of proline, Na+ and K+ were measured. The results showed that generally in each of gamma ray treatment, amounts of proline at 120 and 150 mM NaCl were significantly more than 0, 30, 60 and 90 mM salt. A significant difference observed only at 150 mM NaCl between irradiated and non irradiated calli. This result could be related to the proline role in osmotic adjustment at high concentration of salt. The amounts of sodium increased by increasing salt the concentration but the amount of potassium decreased. These results showed that the sodium influx inhibited the potassium uptake, and may be because of strong inhibitory effect of sodium on the potassium uptake system or efflux potassium from the cells. The Na+/K+ ratio decreased at 150 mM by 60 and 80 Gy of gamma radiation.

86-92

Authors: Akram Zia, Farkhonde Rezanejad and Abbas Safarnejad

Thyme (Thymus vulgaris L.) is an aromatic and medicinal plant which is very important for the herbal industry. In this research, in vitro selection for NaCl tolerance was investigated in this plant. Hypocotyl and shoot explants (apical meristem and cotyledonary leaves) of sterilized seedlings were cultured in MS medium supplemented with different combinations of 2, 4-dichlorophenoxyacetic acid (2, 4-D), napthaleneacetic acid (NAA), kinetin (KIN) and N6-benzyladenine (BA) for callus induction. Results showed that the maximum frequency of callus induction was obtained on MS medium containing 1:0.5 ratio of 2, 4-D:Kin (mgl-1), while optimal callus induction with the best quality and regeneration potential was achieved in 1:1 ratio of NAA:BA (mgl-1). The calli grown in 1:1 ratio of NAA:BA (mgl-1) were transferred to NaCl supplemented medium at 50, 75 and 100 mM concentrations. Fresh and dry weights, percentage of necrosis and regeneration of calli were determined after 4 weeks. There were significant differences between fresh and dry weights of calli in different concentrations of NaCl. The highest and the lowest of fresh and dry weights of calli from hypocotyl explants were observed in 0 (control) and 100 mM NaCl concentrations, respectively. But fresh weight of shoot-derived calli induced from shoots reduced only in 100 mM NaCl and the dry weight of them was not significantly different. The necrosis percentage increased by increasing the salt concentration. Callus regeneration just occurred at the concentration of 50 mM of NaCl and all regenerated shoots well rooted on half strength MS medium, with 0.8% (w/v) sucrose and without growth regulators.

10-14

Authors: Asghar Mosleh Arany

This study examines the assumption that plant resistance to herbivory has fitness costs. To assess costs, a standard method was used for examining the significant negative genetic correlation between the resistance character and damage in the presence of herbivory and with fitness in the absence of herbivory. Seeds of five plants from four genotypes of Arabidopsis thaliana were sown under controlled conditions in a growth chamber. Half of the resulting two months-old rosettes were used for glucosinolate analysis and for herbivory assessment. The other half were transplanted into an enclosure in the natural habitat of this plant and their fitness (fruit number) were measured after harvesting the plants. Caterpillars from Spodoptera exigua were obtained from lab culture for herbivory assessment. Two second-instar caterpillars from S. exigua were placed on each of the rosettes. Larval weight of caterpillars was measured after 5 days. One hundred mg dry mass of leaves from 5 rosettes of each genotypes were used for HPLC analysis. There were genetic variations in types and quantities of glucosinolate between genotypes. The results from herbivory assessment showed that the larval weight of S. exigua fed on some genotypes was significantly lower than others, and therefore there was genetic variation in resistance to herbivore for A. thaliana genotypes. The statistical analysis showed that the larval weight of S. exigua was negatively correlated with the total glucosinolate concentration and with fruit number. Therefore, under the condition of this experiment, glucosinolates reduced damage by S. exigua and exhibited significant fitness costs.

29-34

Authors: Fatemeh Rostami and Ali Akbar Ehsanpour

Potato (Solanum tuberosum L.) auxiliary buds c.v. White Desiree were cultured in MS medium containing 0, 50, 100, 150 and 200 µM concentrations of silver thiosulfate (STS) under in vitro condition. After eight weeks, the effect of silver ions (Ag+) in the form of silver thiosulfate complex (STS), as an ethylene action inhibitor, on chlorophyll contents of leaves, ascorbate peroxidase, guaiacol peroxidase and catalase activities of roots and leaves were studied. Application of silver (STS) in culture medium increased chlorophyll content comparing to the control plants significantly. After treatments of potato plants with STS, ascorbate peroxidase and guaiacol peroxidase activities in roots were higher than shoots while catalase activity was higher in leaves than roots. However, increasing of STS concentration in the culture medium resulted in higher activities of antioxidant enzymes with some variations.

42-48

Authors: Maryam Shahrtash, Sasan Mohsenzadeh and Hasan Mohabatkar

In recent years, several plant species have been used as bioindicators, and several tests have been developed to evaluate the toxicity of the environmental contaminants. In this study, the root length and DNA band pattern of root tips in maize (Zea mays L.) seedlings were exposed at different concentration of cadmium pollutant (40 and 80 mg L−1). The results indicated that the root length of maize seedlings reduced with an increasing cadmium concentration. A random amplification of polymorphic DNA (RAPD) analysis from the extracted DNA was carried out using twenty three 10-base pair random primers. Eleven primers produced 72 bands between 221-3044 base pairs in gel electrophoresis. DNA damage became evident as the presence and/or absence of DNA fragments in the treated samples compared to the control groups. The number of disappearing bands in profiles increased from 33 at 40 mgL-1 of cadmium concentration to 45 after exposure to 80 mg L−1 cadmium concentration compared to total bands in control. Three new bands appeared in 40 mgL-1 of cadmium concentration but five in 80 mgL-1 of cadmium concentration. The results showed that RAPD analysis could be a useful tool for detection of genotoxic effects of cadmium toxicity on plants.