فهرست مطالب hassan ebrahimzadeh

Fusarium seedling blight is a disease of cereal crops caused by a group of trichothecene producing Fusarium species such as Fusarium graminearum. Control of seedling blight has received less attention than control of Fusarium head blight. Application of chemicals which activate plant defense mechanisms before pathogen attack without environmental side effects of protective chemical agents have stimulated great deal of researches in this area. Hence in this study, the effect of seed priming with salicylic acid on Fusarium seedling blight incidence and severity was investigated. According to our results seed priming with salicylic acid improved wheat defense against Fusarium seedling blight in both cultivars. Salicylic acid treatment induced chitiniase gene expression in both cultivars as compared to their controls; however, this increase was much higher in salicylic acid treated Falat than salicylic acid treated Sumai3. Based on the results, increase in gene and protein expression of chitinase could induce host resistance against Fusarium seedling blight caused by F.graminearum.

Cyanobacteria are an important source of natural products. In this article, we briefly review the responses of cyanobacteria to different stresses. Abiotic stresses (temperature, salt, heavy metals, metalloid and ultraviolet (UV) influence cell growth and metabolism in cyanobacteria. Salt stress is a major abiotic factor that decreases the growth of cyanobacteria and affects the different processes including photosynthesis, respiration, and metabolism. The basic mechanisms for salinity adaptation include the active extrusion of inorganic ions and the accumulation of compatible solutes such as sucrose, trehalose, glucosyl glycerol, and glycine betaine. Cyanobacteria have a complex antioxidative system including enzymatic and nonenzymatic antioxidants for mitigation of oxidative damage under salt stress. Cyanobacteria have some defense mechanisms for the decline of the direct and indirect destructive effects of UV. These mechanisms include avoidance, scavenging of reactive oxygen species (ROS), synthesis of UV-absorbing/screening compounds such as mycosporine-like amino acids and scytonemin, repair of UV-induced damage in DNA, and resynthesis of proteins. Metals are involved in key metabolic pathways as redox cofactors in proteins. High concentration of metals causes the generation of ROS and oxidative damage. Thus, the major role of metal homeostasis in maintaining the intracellular concentration of metal within a range compatible with cell viability becomes evident. The biosynthesis of metabolites can be triggered by a number of abiotic stresses because they affect metabolic pathways.

This work evaluated the effect of drought stress on seedling growth, protein, soluble sugars, and phenolic compounds of two cultivars of canola (RGS003 and Sarigol). Drought stress was induced with polyethylene glycol (PEG) at 0, 5, 10, and 15%. Drought stress increased root fresh weight in both cultivars and the effect of drought was more pronounced in RGS003. Shoot fresh weight reduced in Sarigol at 10 and 15% of PEG. Drought stress significantly increased seedling fresh weight in RGS003. Sarigol accumulated higher amounts of protein as compared to RGS003. At all PEG concentrations, the soluble sugars contentwas higher in Sarigol as compared to control. Total phenol content was enhanced at higher drought level (15%) while flavonol content increased at lower level (5%) in both cultivars. Phenylalanine ammonia-lyase (PAL) activity and its relative expression were increasedin RGS003 at 10% of PEG. Overall, RGS003 cultivar had more capacity to tolerate drought stress than Sarigol cultivar.

Environmental stresses are of main factors affecting the olive cultivation programs in arid regions. Morphological and functional characteristics and the amount of leaf nutrients in 11 cultivars of olive (Zard, Roghani, Voliotiki, Arbequina, Karidolia, Oblonga, Amigdalolia, Koroniki, Leccino, Conservolea and Korfolia) grown in Tarom region under saline conditions and irrigation with salty water were studied. The results showed that, the cultivars were different in morphological traits (number of inflorescences on branches, number of flowers in inflorescences, the number of fruits per branch, the final number of fruits on the branches, chlorophyll index) and leaf nutrient contents (boron, copper, zinc, manganese, iron, potassium, phosphorus, nitrogen, sodium, chlorine). The highest fruit number was recorded in Arbequina (8.66), Korfolia (7.33) respectively and the lowest amount was recorded in Roghani (1.66), Zard (3.33) and Karidolia (3.33) respectively. The results showed that Koroniki and Amigdalolia cultivars contain less amounts of sodium and chlorine in their leaves, which is probably due to the resistance of these cultivars to salinity conditions and can be taken into consideration for salinity resistance. .

Lippia citriodora H.B.K. is a valuable medicinal plant of Verbenaceae family. This study was calculated to evaluate potential role of salicylic acid (SA) in diminish the harmful effects of drought stress on L. citriodora plants. SA (0.5 and 1 mM) was used to L. citriodora plants grown under stressed (5, 10, 15 and 20% PEG) and unstressed conditions. Fresh weight (FW) and relative water content (RWC) significantly decreased under water deficit stress. Increase in hydrogen peroxide (H2O2) and malondialdehyde (MDA) content indicated drought-induced oxidative stress in L. citriodora. Water deficit stress significantly increased the protein content, proline content and antioxidative enzymes activities. The exogenous application of SA to drought-stressed plants reduced the content of MDA and H2O2 and increased superoxide dismutase (SOD), peroxidase (POX) and chlorophyll content. It is suggested that SA minimizes the negative effects of drought stress and could be used for amelioration of drought stress in L. citriodora.

This study was conducted to investigate some biochemical and physiological reactions of different olive cultivars (Olea europaea L.) against salinity stresses in three different experiments, experimental settings and contexts in Iran over a period of three years. In order to study the effects of salinity and penconazole combination on physiology of four olive cultivars, a factorial experiment was conducted. Studied factors were included of cultivar at for levels (Conservolea, Koroniki, Zard, Roghani), salinity stress (zero, 100 and 200 mM) and penconazole at three levels (zero, 10 and 15 mM). The results of the experiment showed that the studied treatments had significant effects on morphological factors, physiological factors, carbon dioxide levels, transpiration, stomatal conductance and photosynthesis rate of different olive cultivars. Among different cultivars, Koroniki and Zard showed higher resistance to salinity. The results of this research could be used in order to choose salinity-tolerant cultivars and cultivars with high oil quality to be used in agricultural, food, and pharmaceutical industries.

Astragalus compactus L. seeds were collected fromTehran of Iran. Plants were grown in growth chamber under 16 h daily light periods and leaves, stems, prdicle and cotyledon leaves explantn from three- week- old sterilized seedlings cut and infected with Agrobacterium rhizogenes Strains 15834, 2659 and WT.Hairy roots obtained from leave and stem explants but did not induce hairy roots of cotyledon and pedicle explants of Astragalus compactus.Strain 2659 resulted in the highest amount of hairy root formation in this Species. Strain 15834 was beneficial but not as effective as strain 2659. In contrast to these two strain, strain WT did not induce hairy roots in any of the explants used in this study. Thus, this strain seems to be totally avirulent to Astragalus compactus.

Aim and Peroxidases functions in plants range from cell wall modulations to hormone regulation، defense mechanisms، indoleacetic acid degradation and stress adaptations. During diverse stress conditions، peroxidases protect plant against the intrinsic and environmental disturbances. In this study، the plant corms were prepared in July. Corms were used as the source of the enzyme extraction and this extract was used for further study. The results were shown for the dormant and waking corms; increasing concentrations of guaiacol above the 70 Mm decreased the peroxidase activity. With respect to the kinetics results، it seems that at least two isoforms of the peroxidases exist in saffron corms and so each isoform could take part in some different processes in saffron growth and development.

Aim and Per o xi d ases a re o n e o f t he m o st i m p o rta n t enz y mes that p artici pa t es in many p h y s i o lo g i c al p rocesses in p l a n ts. Peroxidases are heme containing proteins that utilize H2O2 in the oxidation of various organic and inorganic substrates. In this research، the activity of peroxidase، was investigated in Crocus sativus L. co r m s extracts. The activity of peroxidase was studied with different c on c e ntr at i o n o f H 2 O 2 and pH measurement.

In this work, interaction study of metal ions with quercetin, the secondary metabolite of plants was investigated by conductometric method and fluorescence spectroscopy. The conductometric study was done in acetonitrile solution. The conductance of the solution is measured after each addition of the quercetin to the cation solution. The fluorescence spectrum of quercetin was recorded in presence and absence of metal ions at maximum wave length (481 nm) upon excitation at 425 nm. Among the many cations titrated with quercetin, Mg2+, Al3+, Pb2+ and Zn2+ enhanced the intrinsic fluorescence of the quercetin while Cu2+, Ni2+ and Co2+ ions quench the intrinsic fluorescence emission of the quercetin solution. These different phenomena are observed due to the different release of absorbed energy in formed complex. The ability of quercetin molecule to form a complex with metal ions may be has an effect in quercetin anti-oxidative properties.

subfamily Salicornioideae (Chenopodiaceae) from Iran. In all studied accessions a basic chromosome number of x = 9 is reported. First chromosome numbers are reported for Halostachys belangeriana (2n=8x=72), Halopeplis pygmaea (2n=2x=18) and Kalidium capsicum (2n=4x=36). The species of the genus Salicornia are divided into tetraploid and diploid groups. The newly described endemic species S. persica is only tetraploid (2n=4x=36). But the diploid group (2n=2x=18) may represent three different taxa.

Leaflets of 313 specimens including 240 simple haired Astragalus species in 38 sections were taken from the herbarium specimens of Research Institute of Forests and Rangelands (TARI). They were analyzed quantitatively for toxic aliphatic nitro compounds. The catabolites of nitro compounds, 3 - nitro - 1 - propanol and 3-­nitropropionic acid, are especially toxic to cattle and sheep. Nitro compounds were detected in 42 of 313 specimens or in 31 species.

The H6H gene for hyoscyamine 6B-hydroxylase (H6H), which converts hyoscyamine to scopolamine, was isolated from Hyoscyamus niger. The roots of 14 days sterile seedlings were transferred to a modified liquid B5 medium containing 1 uM indolebutyric acid, and after appearance of the lateral roots, subcultured in a free hormone medium. Following a week, its genomic DNA was extracted and PCR performed. By extraction an accurate DNA and using suitable primers, H6H gene can be isolated completely.