جستجوی مقالات مرتبط با کلیدواژه « سیتوکینین » در نشریات گروه « زیست شناسی »

Common boxwood (Buxus sempervirens auct non L.) is a hard-rooted shrub with slow propagation rate. This plant species is in danger of extinction due to invasion of a type of fungus named Calonectria pseudonaviculata. The purpose of this research was investigation of the effect of different concentrations of BAP and NAA (0, 0.5, 1, 1.5 and 2 mg/L form each two) on micropropagation of B. sempervirens. Sterilization of explants of this species is very difficult. Combined application of disinfectants is proposed. Results of micropropagation showed that the largest number of shoots (6.60/plantlet) was obtained in apical buds expalnts treated with 1 mg l-1 BAP. Maximum number of node (5.50/plantlet) and number of leaf (8.10/plantlet) were obtained in media enriched with 1 mg l-1 BAP along with 0.5 and 2 mg l-1 NAA, respectively. The highest root length (10.15 cm/plantlet) was obtained in explants treated with 1 mg l-1 BAP along with 1 mg l-1 NAA. Also, the largest number of root (8.20/plantlet) was calculated in explants treated with 0.5 mg l-1 BAP together with 1 mg l-1 NAA. After propagation, plantlets were transferred to a bed containing peat and perlite with ratio of 1:1 for acclimatization. About 90% of them were recovered and survived. These survived plantlets were morphologically similar to the mother plants.

This study aimed to access the rapid and improved propagation protocol production of Zamifolia plant using tissue culture.

For callus formation and regeneration, two independent factorial experiments were carried out in a completely randomized design with 3 replications in the tissue culture laboratory of the National Research Institute of Flowers and Ornamental Plants in 2018. In the first experiment, to induce callogenesis, 2,4-D (0, 1, 2, and 4 mg/l) and BA (0, 1 and 2 mg/l) were used. In the second experiment, or regeneration of explants, NAA (0 and 0.5 mg/l) and BA (0, 0.5, and 1 mg/l) were applied.

The results of the callogenesis experiment showed that a modified basal MS medium with concentration of 2 mg/l BA and 1 mg /l 2,4-D produced the best callus with 85% regeneration. At the regeneration stage of the callus, 0.5 mg/l BA and 0.5 mg NAA produced the highest number of seedlings and regenerated tubers (90%). Subsequently, single tuber seedlings were successfully adapted to 80%-90% in the cocopeat and perlite substrates.

The results were successful and could be possible to achieve the callogenesis and regeneration of Zamifolia plant with the formula presented and recommend as practical a protocol for commercial micropropagation of this valuable ornamental plant.

Deterioration of seed is one of the vigor reducing factors limiting seed germination. Determination of factors affecting seed deterioration is important. In order to determine the effect of plant hormones on germination characteristics and antioxidant enzymes activities of deteriorated corn seeds an experiment was carried out at seed and biotechnology laboratories of College of Agriculture, Tehran University in 2019. The study was designed with a factorial experiment based on completely randomized design (CRD) with four replications. The experiment treatments included varieties at 2 levels (704 single cross hybrid and 260 single cross hybrid), accelerated aging at 4 levels (0, 5, 10, and 15 day), and hormones at 2 levels (gibberellin and cytokinin). Seed deterioration reduced germination indexes and peroxidase and catalase enzymes activity. Treatment of deteriorated seeds with cytokinin and gibberellin increased antioxidant enzymes activities. Cytokinin was more effective than gibberellin in increasing the activities of antioxidant enzymes in deteriorated seeds. Results indicated that low seed vigor decreased the activity of enzymes and plant hormones as an agronomy solution compensated for the loss in low vigor seeds. Also, cultivar 704, with a higher vigor indicated amore enzyme activity than cultivar260.

In order to investigate the effect of dual phosphorus and Azospirilum solubilizing bacteria on hormonal condition and barley grain yield under different levels of nitrogen, an experiment was conducted in Agricultural Research Station of Islamic Azad University of Karaj, in 2014. The experiment was based on a factorial split plot design in a randomized complete block design with three replications. The treatments included the main factor of the Nitrogen fertilizer in four levels (0, 50, 75 and 100%, equivalent to zero, 150, 225 and 300 kg per Hectares respectively) and sub factors including Azospirilum lipophorm bacteria in two levels (application and non-application of bacteria) and Pseudomonas fluorescens bacterium in two levels (application and non-application of bacteria). The results showed that application of 75% nitrogen and A. lipophorum and the application of the main treatment of P. fluorescens produced the highest amount of auxin hormone. The interactions of urea and A. lipophorum and the dual interactions of A. lipophorum and P. fluorescens produced the highest levels of cytokinin hormone. The levels of hormones showed in the triple treatments of 100% nitrogen, A. lipophorum and P. fluorescens bacteria compared to control treatment (not treatments) had 261.1% difference. The highest grain yield were observed in p. fluorescens (4700 kg ha-1) treatment and using 100% application of urea and A. lipophorum (5500 kg ha-1). As a result, the application of nitrogen fertilizer and the use of both types of biological fertilizers led to an increase in the production of hormones that increased root growth, ultimately, increased water absorption and nutrients from the soil and increased grain yield.

To investigate the effect of herbicide Trifluralin and the role of magnetized water on enzymatic activities and content of proline and growth substances including gibberellin (GA3) and cytokinin (6- benzyl amino purine), an experiment was conducted using squash (Cucurbita pepo L. var. Shiraz Hybrid F1) seedlings. Four levels of trifluralin (0, 5, 15 and 25 ppm) and irrigation by distilled and magnetized water were applied in a completely randomized design in 3 replicates at Urmia University in 2016. Different levels of trifluralin were added to pots 2 days after planting. Seedlings were treated by modified Hoagland solution with diurnal temperature 30:18 °C, relative humidity of 70-80 percent and light period of 16:8 hr, during a 5-week growing period in growth chamber. The effect of magnetized water and trifluralin on ornithine amino-transferase (OAT), proline dehydrogenase (PDH) and content of proline in both shoots and roots as well as GA3 and cytokinin was significant (p>0.01) according to ANOVA. The content of proline and OAT in roots and shoots as well as GA3 and cytokinin increased significantly, although the PDH of roots and shoots decreased under the influence of magnetized water. The content of proline and OAT increased and GA3, cytokinin and the activity of PDH declined by the increase of the levels of trifluralin. Overall, it can be concluded that the growth and biochemical indices of squash plants were improved by magnetized water under toxicity of herbicide trifluralin.

Box tree (Buxus hyrcana Pojark.), is an ornamental tree and shrub species that has application in various industries. Growth and development of box tree is very slow, its rooting is hard and is under danger of extinction. Thus, the purpose of this research was investigation of the effect of different concentrations of BAP and IBA (0, 0.5, 1, 1.5 and 2 mg l-1 form each two) on micropropagation of box tree. The experiment was carried out as factorial based on a randomized complete block design in four replications. Results of the present research showed that the largest number of shoots (6.200/plantlet) was obtained in apical buds expalnts treated with 1 mg/L BAP along with 0.5 mg/L IBA. Apical bud explants were produced the maximum node number (4.100/plantlet) in medium containing 1 mg/L BAP and the largest number of leaf (with average of 6.566/plantlet) along with 1.5 mg/L IBA. Also, the largest number of root (6.466/plantlet) was calculated in explants treated with 1 mg/L BAP plus 1.5 mg/L IBA. Plantlets were transferred to pots containing peat and perlite with ratio of 1:1 for acclimatization. The pots were kept in a greenhouse with temperature of 24-26ºC and relative humidity of 70% and periodic irrigation. Around 90% of those were healthy. These acclimatized plantlets were similar to mother plants.

The purpose of this study was to check the possibility of callus and somatic embryogenesis in date palm cv. Khazravi using different explants including leaves, green fruit, immature seed, endosperm and green fruit pericarp. In the culture of leaves in the medium contains different plant growth regulators including 2,4-D, BAP and TDZ, highest callus induction was achieved in medium supplemented with, 5 mg.L-1 2,4-D, 2 mg.L-1 BAP and 4 mg.L-1 TDZ, and in treatment with 5 mg.L-1 2,4-D, 1 mg.L-1 BAP and 4 mg.L-1 TDZ. By using explant of immature fruit, found that when two growths regulative, TDZ and 2, 4-D in amount of 5 mg.L-1 are in the culture medium callugenesis and embryogenesis was achieved. The endosperm cultivation with pericarp and embryo in the same medium showed that the presence of two growth regulators 2,4-D and TDZ have been useful for callus production. Also in endosperm with zygotic embryo culture, embryo development and the root and shoot were formed after three months. Endosperm culture, in the culture medium containing various auxins and pericarp culture showed no any reactions. In general, these results showed that in date palm cv. Khazravi, treating the explants of leave and immature fruits with appropriate concentrations of plant growth regulators auxin and cytokinin, can induce callus and embryo.

Dunaliella salina cultivation is very important because of the ability of these organisms in the production and accumulation of bioactive substances such as carotenoids, economically. This microalga belongs to green alga and inhabitant in salt water. Nevertheless, current yield of microalga-based procedures is still very low, which has restricted their scale-up culturing. This study reported a growth regulator of cytokinin (BAP) effect on growth and physiological characteristics of the Dunaliella. BAP concentrations were zero, 2, 4, 6, 8, 10 and 12 mg.ml-1. After 4 weeks of treatment, increasing in BAP concentration led to a significant increase in the growth rate and Dunaliella cell number. BAP also increases the concentration of photosynthetic pigments, protein and sugar significantly. It can be concluded that the use of 12 mg.ml-1 BAP could increase cell number of Dunaliella about 63% and growth rate about 60% that it may be were the result of improvements in the efficiency of photosynthesis and cell division.

Auxin and cytokinin are two phytohormones which are effective for various vital processes such as plant growth, development and coordinating the responses to the environmental stimuli. It has been argued that these two phytohormones can affect the process of organogenesis by balancing each other's level. The MS medium including 2 mg/lit of BAP hormone and the MS culture medium including 1 mg/lit of NAA hormone and 0.05 mg/lit of Kenitine hormone were respectively used as media for regeneration and callus formation of the tobacco explants. The amounts of Auxin and cytokinin were estimated in the first, second and third months after regeneration in the new shoots and the first generation callus respectively. The results of the above analyses revealed the proportion of Auxin to cytokinin in the time span of three months and this proportion confirmed the quick and preventing effects of auxin in early stages of growth on synthesis and amount of cytokinin. However, the preventing effects of cytokinin on auxin are slow and are probably through managing and changing other developmental processes. In addition, the amount of auxin and cytokinin in callus was lower compared with the amount of it in the control plant. This can be due to the fact that the cells of the callus are not distinctive and are different from the cells of the leafs which have compartment and different sources for the synthesis of hormone, in fact, the only available hormonl source for calluses is the one provided in the culture medium.

This experiment was conducted in order to investigation the effect of different concentrations of kin (0, 1 and 2 mg.l-1) and Putrescine (0, 20, 40, 80 and 160 mg.l-1) with 8% sucrose and 8% agar on the microtuberization of potato. This study was conducted at the Plant Tissue Culture Laboratory, Department of Horticultural Sciences, University of Tabriz. This study was conducted as a factorial experiment in a completely randomized design with three replications. Results of data analysis showed that none of the traits except percent microtubers non dormant in the second month, and shoot weight were not affected by different concentrations putrescine. Percent of non dormant microtubers in the second month increase on concentration of 20 mg.l-1 and increase shoot weight was 80 mg.l-1 putrescine. However, the effect of different concentrations kinetin was significant in relation to the creation microtuberization. In this experiment, the best concentration of kinetin for most traits microtuberization 2 mg.l-1. Also the best of putrescine concentration for weight microtuberization in media containing 2 mg.l-1 kinetin, 40 mg.l-1, which increase microtuber weight was 0.16 mg.l-1

The effect of different cytokinins on micropropagation of lavandula vera were investigated. Two nodal explants from greenhouse plant were cultured in MS medium supplemented with benzyl aminopurine (BAP), 2-isopentenyl adenine (2ip), Kinetin (Kin) solely or in combination. Results indicated that shoot proliferation depended on type and concentration of hormone. The highest number of nods and new shoots per explants and stem length was produced in the medium with BAP(2 mgl-1). Growth of internodes was significantly increased in the medium with Kin and 2ip (1 mgl-1).In the subculture media, the highest number of nodes and new shoots per explants was obtained in the medium with BAP (1 mgl-1). Maximum of internode length was achieved in the medium with Kin (2 mgl-1). In vitro shoots were rooted in vitro or ex vitro. By using in vitro method, microshoots were cultured in the media supplemented with different concentration of indole butyric acid (IBA) and Kin. In ex vitro method, the base of microshoots was treated with IBA (300 mgl-1). The highest number of roots as well as length of roots was obtained in ex vitro rooting method.

Effect of salinity, ammonium and cytokinin on biomass and the content of agar in Gracilaria corticata algae were evaluated in a period of 42 days under laboratory condition. The alga G. corticata was sampled from coasts of Bostaneh port in Hormozgan province in June 2009. The algae were raised in aquariums 40.30.60 cm with 20 liter capacity, by suspension method in 3 replicates under light intensity of 3300 lux and 25oC temperature condition. The algae were cultured under salinities 25, 35 and 45 PPT, ammonium concentrations (0.00, 0.001 and 0.002 gram per liter) and cytokinin (0.01, 0.001 and 0.0001 mol). The algae were harvested once a week and weighted. At 6 weeks of experiments, the algae were collected, dried and weighed. The highest biomass of G. corticata was at 25 PSU (4.58 grams), 0.01 mol cytokinin (14.88 gr) and 0.002 mol ammonium (26.34 gr). Maximum level of agar was observed in ammonium concentration of 0.002 equal to 32.56 percent. The results of this work showed that G. corticata is one of the commercial algae in the world and this alga needs to be cultured near estuaries with high amount of ammonium.

In order to evaluate the effects of appilcation of cytokinins and abscisic acid on two varieties of wheat (Pishgah and MV-17) under drought stress, a split splitplot experiment based on completely randomized block design with three replications, was carried out. The measured traits included the following cations: estimation content of Na, Ammonium, K, Mn, Ca, Mg, Fe and Zn in plants. Results showed that drought stress had a significant effect at the 1% level on all contents of cations (except for ammonium at 5%). There were significant differences between varieties on Na and Zn content at the 1% level and ammonium and Fe at 5% level. The results also showed that Na and ammonium in drought stress and other measured elements in normal conditions were more than those of other treatments. Varieties were different at uptake of Na, ammonium, Fe and Zn which variety of Pishgam uptake Na and ammonium less than that varieties and also uptake Fe and Zn more than it.

Solanaceous plant, Datura innoxia, has valuable tropane alkaloids pharmaceutical effects. In this study, seed zygotic embryos were cultured in vitro and plantlets were produced and explants with single internodes and two auxiliary buds from the produced plantlets were cultured in B5 medium with different concentrations of IAA (0.5, 1, 1.5, 2 mg/L), NAA (0.5, 1, 1.5, 2 mg/L) and BA (0.5, 1, 1.5 mg/L) to investigate the effects of the growth regulators on callus production, organogenesis and total alkaloid contents. Concentrations of the last two hormones were used reciprocally. Total alkaloid concentrations of calli were identified by UV spectrophotometer at 258 nm and callus total alkaloid contents and were compared with the content of plantlets. Results showed that, in the presence of both NAA and BA, explants formed callus and increase of NAA concentrations, in turn, increased callus weights and total alkaloid contents as well. IAA had no significant effect on callus and organ induction. Comparison of total alkaloid contents of calli with shoots and roots of Datura innoxia plantlets in hormone free B5 medium, showed that the alkaloid contents of calli were lower than differentiated tissues in hormone free B5 medium, but the use of NAA and BA hormones caused an increase in alkaloid contents of calli as compared with in vitro cultured organs.

The effects of different cytokinins (benzyl amino purine(BAP), Kinetine (Kin) incombination with different auxins(Indole butyric acid(IBA), 2,-dichlorophenoxy aceticacid (2,4-D) were investigated on callogenesis and organogenesis of Chrysanthemummorifolium Ramat L. Leaves explants were cultured in the MS medium supplementedwith different auxins and cytokinins. Results of using IBA and BAP in the media indicatedthat calli which were taken from medium with IBA (2 mgL-1) and BAP (0.5mgL-1) produced roots and callus of IBA (1 mgL-1) and BAP (1mgL-1) produced shoots.By using 2,4-D and Kin in the medium, rhizogenesis were occurred in the media supplemented with 2,4-D (0.5, 4 mgL-1) and Kin (2 mgL-1).Subculture of calli increasedrooting. Calli of medium with 2,4-D (0.5 mgL-1) and Kin (2mgL-1) produced shoot afterthe first subculture in the free hormone medium. In the 2,4-D and BAP treatments,maximum level of callogenesis and rhizogenesis were achieved. Calli in the mediumsupplemented with 2,4-D (0.5 mgL-1) and BAP (1mgL-1) produced roots and shoots.