فصلنامه زیست شناسی گیاهی ایران
سال هفتم شماره 3 (پیاپی 25، پاییز 1394)

In this research, to evaluate the antioxidant activity of leaf Pterocarya fraxinifolia (Juglandaceae) and Ficus carica (Moraceae) extract were carried out by spectrophotometry and high performance liquid chromatography methods. The leaves of P. fraxinifolia and F. carica were collected from Whitney and Shast Kalate (Golestan), Noor (Mazandaran) and Asalem (Guilan) forests in Iran. Methanolc extract was used in different experiments. The phenolic compounds (gallic acid, coumaric acid and quercetin) were also measured by using high performance liquid chromatography (HPLC) method.The maximum IC50 for DPPH radical-scavenging activity (595.12±21.4 μg ml-1) were observed in P. fraxinifolia leaves. According to the inhibition time, phenolic compound (gallic acid, coumaric acid and quercetin) in F. carica leaves and gallic acid and coumaric acid were detected of Pterocarya leaves methanol extracts. The maximum amount of gallic acid (78.93) and coumaric acid (8.14) in extracts Pterocarya leaves Asalem and the lowest gallic acid (8.56) and coumaric acid (0.89) milligrams per gram was observed in Ficus leaf of Noor forest. Based on the standard chromatogram retention time of gallic acid (2.383), coumaric acid (3.817) and quercetin (7.217) mg/g was reported. This study showed that soil factors, such as potassium, sodium, phosphorus and nitrogen compounds with antioxidant phenolic extracts of the leaves of both plants there is a significant correlation.

Drought stress impact photosynthesis and stomatal conductance, and may reduce the overall production capacity of plants. Since exogenous application of salicylic acid (SA) can partially alleviatebe increased the negative effects tolerance of drought stress by improve the metabolism pathways and increase the net photosynthesison plant photosynthesis and metabolism, the main objective of this study was to clarify the roles of SA in enhancing 28 days tobacco (Nicotiana rustica Basmas) tolerance to drought stress (50% FC). The results indicated that foliar application of SA (0.5 mM) influenced negatively net CO2 assimilation rate and stomatal conductance and led to reduction of shoot and root dry masses. In contrast, the stress did not reduce significantly the maximal quantum yield of photosystem II (PSII). This that can be explained by enhancement of efficiency for dissipation of excess photon energy in the PSII antenna, determined as non-photochemical quenching, and consequently further protection of PSII from photodamage. Thus, under more drought stress, the reduction of photosynthesis of tobacco plants was due mainly to reduction of stomatal conductance. Under water-deficient conditions, plants showed an increase in chlorophyll a and amino acids concentrations in the leaves when treated with SA while this change for net photosynthesis was negligible. Our results indicated showed that the foliar application of SA had no ameliorative effect on tobacco growth under drought stress, because its effect on elevation of transpiration rate did not increase net photosynthesis under drought condition.

Callus culture is necessary for production of suspension cell culture in plant breeding programs. Regarding to the application of Papaver bracteatum as an important medicinal plant in production of benzophenantridine alkaloids, this study was performed to find the most suitable hormone combination and explant type for achieving to high percentage of callus induction fresh weight and somatic embryogenesis in this plant. For this purpose, hypocotyl explants were cultured in ½MS media containing active charcoal (2 and 4 mgL-1) in combination of different concentrations of NAA, 2,4-D (0, 1, 2, 3 and 5 mgL-1) and BA (0, 0.1 and 0.5 mgL-1). The seed explants were cultured in same treatments without active charcoal. Also, somatic embryogesis induction using seed explants in ½MS media containing different concentrations of NAA and 2,4-D (0, 0.5, 1 and 2 mgL-1) with BA 0.5 mgL-1 were investigated. The results showed that the highest percentage of callus induction (43.6%, 54%) in hypocotyls explants were obtained in the ½MS media containing 2 mgL-1 active charcoal and 2 mgL-1 2,4-D and 5 mgL-1 NAA in companion with BA 0.5 mgL-1 respectively. The maximum callus induction (84%) was obtained in ½MS medium with 1 mgL-1 2,4-D without active charcoal. The highest callus fresh weight (0.35%) was obtained in MS media with 0.5 mgL-1 2,4-D andthe maximum rate of somatic embryogenesis induction (77%) was observed in ½MS media containing 1 mgL-1 2,4-D with 0.5 mgL-1 BA.

Artemisinin is a secondary metabolite with antimalarial properties. In addition to this, it has activities against a wide variety of cancers such as human leukemia, breast and colon cancer, and carcinomas. It has also shown anti hepatitis B, anti-HIV, anti-leishmanial and anti-schistosomiatic activities. This compound is produced by many species of the genus Artemisia, and for the first time it was detected in A. annua. In this study, the expression patterns of ADS, DBR2 and SQS genes were investigated in five species include A. annua, A. dracunculus, A. vulgaris, A. absinthium, and A. sieberi. Extraction of total RNA and production of cDNA were from the two-month-old plant leaves. Semi-quantitative RT-PCR was performed to analyse the gene expression of these genes and actin gene was used as the internal control. Also, PCR products were loaded on the agarose gel (1 % w/v). Quantification of band density was carried out using Imag J software and data analysis was conducted using the SAS software. Results showed that expression pattern of the studied genes were different, so that a higher transcript level of SQS gene was observed in A. vulgaris, A. dracunculus and A. annua. Transcript level of ADS was higher than other genes in A. sieberi and A. absinthium. Different expression patterns of these genes can be interpreted as potentially different artemisinin contents in these species.

Phenylpropanoid compounds as secondary metabolites are synthesized by plants during development and in response to stress. Phenylpropanoids contribute to the compounds of plant pigmentation, antioxidants and protective agents and also play a regulatory role in growth and morphogenesis. In this research, samples of blade and sheath of leaf,, stem, and root of Saccharum officinarum (cultivar CP69-1062) during the germination, tillering, grand growth, and maturation stages were prepared. In order to studying biochemical changes of phenylpropanoid compounds during development of sugarcane, PAL activity enzyme, phenolic, flavonoids and flavonols component in samples were analyzed. The study of changes of enzyme activity in different tissues during developmental stages showed high enzyme activity of PAL in leaves during all of developmental stages and in sheath during grand growth stage. Enzyme activity was increased in stem during grand growth stage and in root during germination stage. Results indicated that changes of concentration of total phenol and the maximum amount of total phenol were detected in leaf during germination and maturation stages, in sheath during germination stage, in stem during grand growth stage and in root during maturation stage (p<0.05). The maximum amount of flavonoids and flavonols were observed significantly in leaves during all of developmental stages. This variation may originate by the existing heterogeneity in different parts of plants and also chemical and biochemical features of this compound. In conclusion, PAL, as a rate-limiting enzyme of the phenylpropanoid pathway, displays critical role in the development of sugarcane, particularly in lignified tissues.

Studying explants affected by Agrobacterium rhizogenes shows that in addition to possible formation of hairy roots, it is likely that callogenesis can be induced in these tissues. The T-DNA region of A. rhizogenes codes enzymes that participate in biosynthesis of plants growth hormones. These hormones also affect callogenesis, hence, the formation of various calluses with different morphological properties are possible. It is very likely that the level of biosynthetic growth hormone, the plasmid carried by each bacteria strain, the position of T-DNA, and the level of gene expression contribute to this morphologic variation. In this study, the root explants of four species of the family Solanaceae namely Atropa belladonna, Datura metel, D. stramonium and Hyoscyamus niger were induced by using different strains of A. rhizogenes (A4, A7, AR15834, AR318, AR9402 and AR9543). Some of these explants entered callus phase and formed various calluses with different colors and shapes. Moreover, in some callus samples hairy roots were also appeared. These variations were probably caused by variations in the levels and ratios of auxin and cytokinine hormons after the induction. As shown in previous studies, the amount of secondary metabolites is reduced due to undifferentiated tissue produced in the callogenesis process.

Soil pollution by oil compounds is one of the most common environmental problems that induce oxidative stress in plants. In this research, for investigate the synergism between soil rhizosphere and diesel degrading bacteria on some growth and biochemical factors of Zea mays (640 and 704) in diesel polluted soils, four different treatments were designed. Various physiological and microbial factors were assayed. The results showed that root and shoot length and total chlorophyll in presence of treatments in both varieties of Z. mays were significantly decreased in comparing to the control plants. Stress caused a significant increase in carotenoids and malondialdehyde contents in diesel treatment and diesel and Peseudomonas fragi bacteria treatment in comparing to control in both varieties. The anthocyanin content and protein were significantly increased in comparing to control. This stress caused an increase in the numbers of degrading and heterotrophic bacteria and dehydrogenase enzyme. Therefore, we can say that diesel treatment decreased the growth of Z. mays and adding the degrading bacteria improved diesel depressing effect on plant growth.