فصلنامه زیست شناسی گیاهی ایران
سال ششم شماره 4 (پیاپی 22، زمستان 1393)

In this study، the total phenol and flavonoid contents and antioxidant activities of dried leaves and fresh and dried tubers of Leontice armeniaca and L. leontopetalum were determined using ferric reducing antioxidant power (FRAP)، reducing power and superoxide radical scavenging percentage. The results revealed that in both species، the content of total phenolic، total flavonoid and FRAP of leaf were greater than tuber. The order of total phenolic and total flavonoid contents and FRAP of leontopetalum was significantly higher than armeniaca (P<0. 05). The highest reducing power was found in leaves of L. leontopetalm and the lowest was found in its tubers. Free radical superoxide scavenging activity in leaves and tubers of L. armeniaca were higher than L. leontopetalum. The dried tubers of both species had higher phenolic content، FRAP، reducing power and superoxide radical scavenging activity than fresh tubers. The high positive correlations were observed between total phenol and flavonoid content / FRAP and reducing power. But، this compound did not show any significant correlation with superoxide radical scavenging activity. The increase of total phenolic content affected the FRAP and reducing power values، however، there was no effect on superoxide radical scavenging activity. This meant that phenolic compounds played a key role in antioxidant capacity and reducing power in the two species، while its superoxide radical scavenging was not only attribute to phenolic compound. So drying could be an effective method for increasing phenolic compound and antioxidant capacity. Also results obtained from this study showed that Leontice could be a source of natural antioxidant.

Tomato (Lycopersicum esculentum Mill.) is one of the most important horticultural crops، belonging to the family Solanaceae. Owing to the significance of tomato as a model plant in genetic studies، little is known about the floral development in this plant. The organogenesis of tomato flowers was studied using epi-illumination light microscopy. The flowers were pentamerous with the acropetal and asynchronous inception of floral whorls. The initiation of sepals، petals and stamens followed helically، unidirectionally and bidirectionally، respectively. The high occurrence of floral abnormalities was remarkable. The initiation of a higher number of organ primordia was observed for sepals، petals، stamens and carpels. The increase in the number of organs resulted from the duplication of organ primordia، especially for the stamen whorl. Based on previous studies، low temperature was probably responsible for the abnormal development of tomato flowers.

Ajwan (Carum Copticum L.) is an important plant in Apiaceae family and has many medical uses. In this research، the effects of water deficit stress on growth، yield، compatible metabolite accumulations (proline and carbohydrates) and plant ingredients were studied under controlled conditions in a greenhouse. Water deficit levels included mild stress (90% field capacity)، medium stress (70% field capacity) and severe stress (50% field capacity). In 50% field capacity، the plant didn''t reach to seeding stage. Also، In this study، seed essence of plants under water stress، levels of 70 and 90% field capacity، was obtained by distillation with water and chemical compounds of essence were analyzed by GC/MS method. The statistical results showed significant effects of water stress on growth parameters، seed yield، proline accumulation، carbohydrate accumulation، oil yield and essential oil percentage. The increase of water stress decreased plant height، number of lateral branches، dry weight and seed yield. However، oil yield، oil percentage، proline and carbohydrate contents increased. The highest amounts of proline and carbohydrate at the 50% of field capacity (high stress) and also the maximum essential oil yield and percentage of essential oil at 70% field capacity were observed. Twenty-one chemical compounds were identified in both of the essences of Carum Copticum، and thymol، gamatherpinen and parasimen in each treatment were changed.

An effective in vitro regeneration system is one of the prerequisites for genetic manipulation of alfalfa (Medicago sativa L.) varieties and genotypes. In this research، somatic embryogenesis of four alfalfa genotypes، 6-18 (synthetic)، 4-14 (Kara Yonje- Karakozlu)، 3-27 (Kara Yonje Maraghe) and y-6 (Regen-SY)، were investigated using leaf and petiole explants. Formation of callus and somatic embryogenesis was significantly influenced by the explant type and interaction of genotype and culture medium. Petiole explants of genotype 4-14 produced the highest yield of callus (0. 406 gr fresh weight of callus). Percentage of somatic embryogenesis and the number of embryos per callus in petiole explants of genotype 4-14 was higher than those of other genotypes and explants. In genotype 6-18، the highest percentage of somatic embryogenesis was achieved on MS medium containing 5 mg/L 2،4-D and 2 mg/L kinetin. There was no significant differences between genotypes and explants in terms of embryo conversion to plantlet، and on average، 58% of somatic embryos converted to plantlet on MS medium. The petiole explants of genotype 6-18 did not exhibit somatic embryogenesis response in medium containing low ratio of 2،4-D: Kinetin (5 mg/L 2،4-D and 2 mg/L kinetin). While، these explants showed somatic embryogenesis in higher ratio of 2،4-D: Kinetin (5:1). The plantlet conversion efficiency of somatic embryos produced through this study was relatively higher and therefore، the method presented in this study could be used in alfalfa genetic manipulation and molecular studies.

Jasmonic acid and its methylated ester (methyl jasmonate)، as natural plant growth regulators، are widely found in plants. In this study، the effect of methyl jasmonate (30 μM)، in the early stages of Nicotiana tabacum L. cv. Cooker 347 growth، on photosynthetic pigments and proline was studied at high concentration of chloride. This experiment was performed in randomized complete block design with 4 replications، during 2011 crop year at Guilan Tobacco Research Center، outside greenhouse and under pot conditions. After transplanting similar seedlings to pots in rapid growth phase، the plants were irrigated with three levels chloride (50، 150 and 300 mg/L) as CaCl2 both in presence and absence of methyl jasmonate for 4 weeks. Data analysis showed that by increasing Cl- concentrations up to 300 (mg/L)، chloride and calcium accumulation of leaves increased، whilst photosynthetic pigments and proline decreased. Exogenous application of methyl jasmonate (30 μM) significantly increased photosynthetic pigments in all treatments and proline in the 300 mg/L treatment. It seemed that the application of external methyl jasmonate (30 µM) could improve tobacco plant injuries at high chloride concentration.

In order to assess corn responses to zinc compounds and auxin (Indole Butyric Acid) foliar application in shoots and roots، a pot experiment was carried out in randomized complete block design in three replications. Results showed that، zinc and auxin increased auxin and abscisic acid concentration both in shoots and roots. Also، fresh and dry weight of shoot and root increased model to foliar application، because protein synthesis was increased. On the other hand، according to unusual case، auxin and ABA showed positive parallel variation both in shoot and root، but this relation was more noticable in shoots.

The paclobutrazol is one of plant growth regulators from triazoles group that is able to protect plants against environmental stress conditions. This experiment was carried out to investigate paclobutrazol (0، 25 and 50 mg/L) effects on reduction of injuries caused by low temperature (5±1ºC) stress in two cultivars of Phaseolus vulgaris [Daneshkadeh cv. (white bean) and Sayyad cv. (red bean)]. The results showed that low temperature stress، reduced fresh weight and dry matter and also reduced length of shoots and roots and leaf chlorophyll contents but increased electrolyte leakage percentage. Paclobutrazol treatment reduced fresh weight and dry matter and length of shoots but increased root dry weight and root development. Moreover، paclobutrazol-treated plants، when exposed to the cold stress condition، showed electrolyte leakage percentage less than control plants. Treatment of seedlings with paclobutrazol led to an increase in chlorophyll contents، either in stress or non stress conditions. White bean was more sensitive to cold than red bean and paclobutrazol affected white bean more than red bean. Therefore، it could be concluded that paclobutrazol treatment improved ability of plant responses to the cold stress and this effect was more remarkable in cold sensitive cultivars.

Drought stress is one of the most important and most common environmental stresses that limit plant growth. Photosynthesis is the main determinant of plant growth and its retention ability under environmental stress condition is important for preservation of growth stability. To study the effect of spraying CCC on photosynthesis activity and essential oil content on ''Foeniculum vulgare''، an experiment was done in split plot design based on complete block with four replications in research field of University of Zanjan in 2011. Levels of drought stress included، control، soft stress (when 30% of available water was out of soil)، severe stress (when 90% of available water was out of soil)، and three concentration of CCC 0، 1500 and 3000 mg/L. The results showed that between rates foliar application on physiologic characteristics as photosynthesis rate، transpiration severity، RWC and TΔ intercellular (Ci)، stomata conductivity، mesophyll conductivity and essential oil content was significant. By spraying 3000 mg/L CCC، balanced the plant position against drought stress and could reduce negative effect. Foliar application of CCC caused significant increase in photosynthesis rate، mesophyll conductivity and significant decrease stomata conductivity، transpiration severity under drought stress and could increase essential oil content under soft stress. In this study، foliar application of CCC to content 3000 mg/L had the highest effect on this characters.

Drought stress is a main limiting factor of turfgrass growth in arid and semi-arid regions. Therefore، in this study، the physiological and biochemical changes in two turfgrass species Agrostis stolonifera and Festuca arundinacea schreb during drought stress (70-75 centibar) in a 40-day period and recovery were investigated. Control plants during drought stress were regularly irrigated at soil field capacity (20-25 centibar). The results showed that leaf relative water content and leaf chlorophyll content with long-term stress decreased. Electrolyte leakage and proline during drought stress significantly increased and in recovery stage، the level of electrolyte leakage and proline reached to the control. The activity of peroxidase and superoxide dismutase in two turfgrass significantly increased after 30 days and then significantly reduced. In F. arundinacea schreb the activity of ascorbat peroxidase after 20 days significantly increased and then significantly reduced. Also، in F. arundinacea schreb species the activity of catalase increased during drought stress and in recovery stage the activity of catalase reduced. In studied species during drought stress and recovery stage، the activity of ascorbat peroxidase and catalase significantly increased compared to the control. These results suggested that the resistant species F. arundinacea schreb، under drought stress had a low level of electrolyte leakage، higher level of relative water content and chlorophyll destruction was less than A. stolonifera.

The production of tetraploid plant was studied in Cannabis sativa L. with colchicine at three different concentrations (i. e.، 0. 0، 0. 1 and 0. 2%) for about 24 and 48 h through dropping method. Flow cytometry analyses were used to confirm the ploidy level. Morphologic and anatomic characteristics between tetraploid and diploid control plants were compared. The results showed that 0. 2% colchicine for 24 h had the best effect. The percentage of tetraploid plants and the survival rate were lowered by increasing the treatment time. In addition، the leaf index and height of tetraploid plants exhibited a significant decrease compared to the diploid plants. The size of leaves'' epidermis stomata were larger in tetraploid plant compared to the diploid ones، in spite of their less density of stomata. However، the amount of total chlorophyll and carotenoids were almost the same in both of tetraploid and diploid plants. In addition، some differences were also observed in the cross section of stem of these plants from the descriptive structure point of view. On the whole، the results introduced usage of the stomata parameters as an effective and convenient method for detecting the tetraploid plants; however، the flow cytometry analysis was more effective in assessing the ploidy percentage.

Olive is one of the most important fruit crops throughout the Mediterranean Basin، mainly propagated by cuttings. The adventitious root development is a key stage in vegetative propagation; however the low rooting capacity of some cultivars severely affects the efficiency of olive clonal propagation. Auxin Influx Carrier gene (AUX1)، plays a key role in lateral root formation in many plant species promoting the export of IAA from newly developing leaves to lateral root primordia. Putative olive homologues were amplified by using degenerate primers designed on the conserved regions of AUX1 transcripts identified in other plants. Transcript and amino acid sequences in root (OeAUX1R) and base of cutting (OeAUX1B) were different causes of polymorphisms relating to possible distinct roles in these tissues. In order to investigate the gene expression patterns، Real-time PCR was performed on cuttings during the rooting stage collected from genotypes characterized by high and low rooting ability. Moreover، the gene expression was investigated on different olive tissues. Preliminary results showed that the expression of OeAUX1B and OeAUX1R in base of cuttings and roots of the high-rooting genotype were higher which suggests the hypothesis of the involvement of OeAUX1 in olive rooting. Bioinformatics analysis revealed that AUX1 gene had 8 exons in olive and the sequence of this gene in plant was conserved during evolution.