فصلنامه زیست شناسی گیاهی ایران
سال ششم شماره 1 (پیاپی 19، بهار 1393)

Olive (Olea europaea L.) is an evergreen tree، traditionally cultivated in the Mediterranean area. Olive tree cultivation is curtailed in cold areas because they can rarely tolerate temperatures at and below -12°C. In recent years، because of high demands for olive oil and its fruit، the cultivation of olive trees has been increased in Iran. To investigate the impact of cold stress on the content of total phenol، antioxidant activity and three major phenolic compounds including oleuropein، hydroxyl tyrosol and tyrosol and also phenylalanine ammonialyase (PAL) activity، one-year old olive cultivars of Sevillana and Frantoio were exposed to low temperatures of 10، 5، 0، -5، -10، -15، -20 and control 20°C for 12 h، gradually. The results indicated that total phenol content، antioxidant activity and PAL activity were increased under cold stress in both investigated cultivars. However، PAL activity in Sevillana showed significant decrease at and below -5°C while in Frantoio cultivar there was significant dwindling blew -10°C. Oleuropein content significantly increased during cold stress but، tyrosol and hydroxy tyrosol content decreased in both cultivars compared with the controls. According to the current results، Frantoio and Sevillana showed different resistance under cold stress، so that Frantoio was more resistant than Sevillana.

Trehalose is an α-α linked glucose disaccharide. Trehalose supplied to the growth medium of Arabidopsis seedlings inhibits root growth، primary leaf development and carbon allocation from shoot to root. In the current study، interaction between trehalose and ascorbic acid on some growth parameters and photosynthetic gene expression was investigated in Arabidopsis seedlings. For this purpose، Arabidopsis seeds were grown on MS medium، MS medium supplemented with 0. 1 mM ascorbic acid، MS medium supplemented with 100 mM trehalose and MS medium supplemented with 0. 1 mM ascorbic acid combined with 100 mM trehalose for 15 days. The results showed that trehalose decreased root length، and dry and fresh weight as well. Meanwhile، the amount of soluble sugar، starch، ascorbic acid، dehydroascorbate، total ascorbic acid and trehalase activity were increased by trehalose treatment. On the other hand، the combination of trehalose and ascorbic acid treatment increased root length، dry and fresh weight and decreased soluble sugar، starch، ascorbic acid، dehydroascorbate، total ascorbic acid and trehalase activity. Gene expression profiling showed that trehalose suppressed SUS، INV and SUC expression. But ascorbic acid partially lowered gene expression suppression mediated by trehalose. In summary، the current results showed that the inhibitory effect of 100 mM trehalose on Arabidopsis seedlings growth can be because of its inhibitory effect on sucrose transport from source tissue (leaf) to sink tissue (root).

Salinity is one of the major abiotic stresses that adversely affects crop productivity and quality. In this study، an experiment was conducted to investigate the effects of salinity stress on some physiological parameters of wheat seedlings. Plants were subjected to three salt treatment i. e. 0 (control)، 100، 150 mM NaCl under controlled conditions. Results showed that increasing salinity caused significant decrease in shoot and root length and dry weight and leaf area، but in contrast، malondialdehyde (MDA) content and catalase (CAT) and guaiacol peroxidase (GPX) activity were increased. Also، increasing salinity significantly decreased K+ and NO3- and significantly increased Na+ and Cl- content.

Epilithic diatoms are a division of Bacillariophyceae which live on stone and hard surfaces. This study was aimed to investigate the population dynamics of diatoms in Babolrud river. Samples were collected from 5 stations from May 2012 through September 2012 in a monthly interval. Temperature، pH، NO3-، PO4- and (EC) were measured for each sampling. Samples were prepared using Patrick and Reimer procedure. 72 taxa were identified، among which 33 taxa (46%) were cosmopolitan or widely distributed. The genera with the highest species were Navicula (12)، Nitzschia (9)، Achnanthes (9)، Cymbella (8) and Gomphonema (6). The decrease in diatoms diversity from upstream toward downstream can be regarded as an indicator of increasing water pollution. Trends in distribution of diatom species in the sampling sites were explained by variations in environmental parameters such as conductivity، pH، temperature، nitrate and phosphate. In highly contaminated sites of the Babolrud River، species such as Gomphonema olivaceum، Navicula pupula، Nitzschia flexa and Pinnularia major were observed، while individuals of Achnanthes clevei، Achnanthes deflexa، Cymbella affinis and Fragilaria virescens were found in sampling sites with relatively less environmental perturbation. We concluded that diatoms can be used as quantitative indicators of environmental conditions in lotic systems.

Environmental stresses including water deficit stress may produce oxidants such as reactive oxygen species that damage the membrane structure in plants. Among the antioxidants، ascorbic acid has a critical role in the cell and scavenges reactive oxygen species. In this research، effects of ascorbic acid at two levels (0 and 10 mM) and water deficit stress based on 3 levels of field capacity (100، 60 and 30%) were studied in tomato plants. Both levels of stress increased lipid peroxidation، reduced the amount of ascorbic acid and glutathione and increased the activity of enzymes superoxide dismutase، catalase، ascorbate peroxidase، glutathione reductase، guaiacol peroxidase and reduced the growth parameters. Ascorbic acid treatment، reduced lipid peroxidation، increased ascorbic acid and glutathione levels and decreased the activity of superoxide dismutase، catalase، ascorbate peroxidase، glutathione peroxidase and guaiacol peroxidase and positive effects of ascorbic acid treatment appeared to improve the plant growth parameters.

In this research، morphology and anatomy of male flower structure in Pycnocycla nodiflora Decne. ex Boiss. belonging to family Apiaceae were studied.. Application of some characteristics such as inflorescence، umbel florets and fruits in the classification of members of this family have paved the way for studies focusing on the flower structure. Morphological and cytohistological studies were performed by stereo- and light-microscopy using fixation and sectioning. Some morphological specificities of flower in this species included compound umbel inflorescences composed of 3-5 umbellules، involucre with 5 short and triangular bracts، 7 flowers in an umbellule، swollen peduncle in male flowers، heteromorphous sepals، color combination of white and purple of petals. Ttrichoms were abundantly observed on most flower parts. Anthers were dorsifix and structures with wrinkled edges were seen in the middle of male flower receptacles. Anatomical studies demonstrated the presence of secretory ducts with shizogenous development in sepal and petal structures. Hair formation on the epidermis of these structures was increased during maturation. Middle layer was transient and tapetum was of secretory type. Simultaneous cytokinesis produced tetrahederal tetrads. Anther dehiscence was longitudinal and released pollen grains were dumbbell shape. Some anthers in flower as well as some pollen sacs in an anther developed insimultaneously.

Transient gene expression is fast، easy and not influenced by positional effects that potentially affect on gene expression levels in stable gene transformation. Transient expression can be applicable using agroinfilteration، biolistic and viral vectors. Agrobacterium mediated transient expression have been shown as an efficient and versatile method for analyzing transgene expression، gene scilencing، host-pathogen interactions، protein-protein interaction، and cis-element/transfactor interaction. A control vector consists of an interon containing reporter gene under control of a common promoter is often required for Cis-acting elemen analysis to standardize the variation. This study was carried out to construct a control vector based on two parental binary vectors، pGPTV and pCAMBIA3301. The constructed vector، pGCGi had an interon containing GUS reporter gene under control of the full sequence of CaMV 35S promoter. The GUS staining results revealed that the GUS intron containg gene cannot produce an active B- glucronidase enzyme in agrobacterial cells. The functional gene expression analysis of the new vector was done using agroinjection and prticle delivery system in tobacco and onion eoidermal cells respectively. The histochemical GUS staining results showed pGCGi could express the reporter gene in plant cells and culd be used as control vector in transient expression experiments.

Saffron is known as one of the most common spices and medicinal plant in the world. Little information is available on the effects of copper and growth regulators on morphological characteristics of saffron. The aim of this study was to evaluate the influence of different concentrations of copper and auxin on morphological properties of root and leaf of saffron. This study was arranged as a factorial experiment in greenhouse condition and in hydroponic system. Copper was used in copper sulfate (CuSO4) form (0، 0. 02، 0. 1 and 0. 2 mg/L) and auxin in naphthalene acetic acid (NAA) form (0، 1 and 2 g/L). Results showed that interaction of Naphthalene acetic acid 1 g/L and copper sulfate 0. 1 mg/L increased root number، as well as root and leaf dry weight. Furthermore، naphthalene acetic acid 1 and 2 g/L in most treatments reduced the number of buds. Copper concentration of corm was increased in 0. 2 mg/L copper sulfate.

Accessibility to a major portion of information about vegetation function of an ecosystem is provided by autecological studies. This type of studies provides valuable information which is necessary for ecosystem management. In this research، characteristics such as: phenology، seed germination، karyotype، palynology and some of biodiversity indices for habitat of Kelussia were studied. The results indicated that Kelussia was a perennial herb، stem is short and covered by sheathing leaf، leaves are basal، flowers are bisexual in compound umbels، inflorescence height between 120-200 centimeters، fruits by two mericarps and seed with 3 ribs. Sprouting of the plant began in early March in the snow and life goes on until early September، when the seeds are mature. Cytologically this species is diploid with basic chromosome numbers x=11. Chromosomes are approximately average in size and karyotype is asymmetric. Chilling had very significant effect on seed germination of Kelussia and soaking treatment increased germination percentage. The palynological observations revealed that pollen grains of kelussia are prolate in shape، are operculate and tricolporate structurally and the surface is regulate. Diversity indices also showed low diversity in region.

Glycine betaine (GB) is an important compatible solute that acts as a substitute for water molecules release protein and membrane protection and also acts as active oxygen scavengers. In some plants، accumulation of this compound causes resistance to various stresses such as low temperature. In this experiment، the effect of exogenous application of GB and low temperature stress was investigated on Mexican lime in factorial experiment based on complete randomized design with three replications. Glycine betaine was applied at five levels (0، 2. 5، 5، 7. 5 and 100 mM) and also plants were subjected to five temperature treatments (2، 0، -2، -4 and -6°C). Results showed that spraying by 7. 5 and 10 mM GB as compared to other concentrations apart from the temperature at 2°C significantly increased the activity of peroxidase (POD) during the stress. Also، 10 mM of GB increased the total protein during the low temperatures in leaf tissues significantly. However، different concentrations of GB had not any clear effact on other characteristics such as lipid peroxidation (MDA)، ion leakage (EC)، total antioxidant capacity (DPPH sc%) and superoxide dismutase (SOD). It seemed that GB had protected the proteins such as peroxidase. In this study SOD content did not change during treatments that may depended on the low duration of stress. In addition، GB without antioxidant role in Mexican lime، could not protect the membrane from proxidation.

Effects of magnetic and electromagnetic fields on the living organisms have drawn attention in the recent years، but their exact mechanisms are still unclear. In the present study، the effects of 10 kHz electromagnetic magnetic field on some physiological parameters of wheat (Triticum aestivum L.) were evaluated. The plants in their reproductive phase were treated for 4 days، each 5 h. Then the iron content، ratio of Fe-bound proteins to total proteins، content، size and secondary structure of ferritin nanoparticles as well as activity of antioxidant system were evaluated. The results showed that in comparison with the control plants، treatment with electromagnetic field significantly increased the iron contents of all organs except seeds and ratio of Fe-bound proteins to total proteins of seeds. The content and secondary structure of ferritin nanoparticles in edible parts of magnetic field treated plants were decreased significantly، but the hydrodynamic diameter was increased significantly compared to the control plants. This treatment also caused the significant increase of catalase activity and remarkably decreased peroxidase activity of wheat seeds، which in turn led to maintenance of membrane lipid peroxidation. These results suggested that electromagnetic field with applied frequency affected wheat plants by changing the content of total iron، Fe-bound proteins special ferritin and its characteristics and activation of antioxidant system.